Geotechnical Engineering for Transportation Projects

The history of geotechnical innovation, from the days of Mesopotamia and Ancient Egypt to current day practice, is discussed with a particular emphasis on its application on transportation projects above and below ground. The role of innovation in the evolution of geotechnical engineering is highlighted in the paper, and the factors that facilitated its application over the past 50 years are presented. Discussed also are the top 10 barriers to the application of geotechnical innovation on current U.S. transportation projects.

This report describes a number of experiences obtained from two projects. Firstly, among a number of significant geotechnical design and construction issues of the Trans-Tokyo Bay Highway project, large scale ground improvement by cement-mixing in place and construction of large offshore embankments using cement-mixed sand are described. The related strength and deformation characteristics of cement-mixed soil are summarised and compared with those of natural sedimentary soft rocks. A new method to determine the design strength of cement-mixed soil, adopted in this project, is described. Secondly, recent construction of a bridge abutment consisting of the backfill of geogrid-reinforced cement-mixed gravel and a thin RC facing structure supporting a bridge girder for a new bullet train is described. This structure is unique in that the backfill supports laterally the RC facing, rather than exerting static and dynamic earth pressure on the facing. Results from triaxial compression tests on cement-mixed gravel and dynamic loading model tests as well as field full-scale loading tests are reported.

This paper presents a case history of the deep mixing method (DMM) as it was developed and applied over a period of ten years during construction of the Boston Central Artery and Tunnel (CA/T). Deep deposits of marine clay were stabilized with DMM for large open cuts at Bird Island Flats and Fort Point Channel, both of which are described with respect to site conditions, soil properties, DMM installation and characteristics, and measured field performance. Topics addressed in this paper include water pressure distribution behind DMM walls, statistical characterization of soil-cement properties, quality control/quality assurance procedures, comparison of measured and numerically simulated deformation in clay stabilized with various configurations of soil-cement elements, and shear modulus degradation characteristics of in situ soil-cement. Recommendations are made for soil-cement properties, installation procedures, analytical modeling, design, and inspection.

Current seismic design guidelines for bridges, as reflected by the recently published NCHRP12-49 Recommended LRFD Guidelines, are placing increasing emphasis on earthquake induced displacements as a measure of seismic demand and performance. Such an approach places increasing importance on improving our understanding of earthquake time histories and nonlinear deformation and ductility behavior of bridge components. Whereas structural engineers have made considerable advances in developing and applying displacement based design concepts over the past 10 years, geotechnical engineers have only recently been addressing issues related to displacement based foundation design, including nonlinear deformation and capacity modeling under earthquake loading. Foundation design issues associated with nonlinear deformation and capacity modeling of piled foundations, shallow footings, and abutments, are reviewed in the context, of displacement based design. As competent foundation soils such as clays and dense sands are ductile and not susceptible to strength degradation, mobilization of foundation capacity leads to performance criteria more related to the effect of ductility demands on the bridge structure and to earthquake induced foundation settlement. Examples associated with earthquake time history loading on piled and shallow footing foundations are used to illustrate nonlinear modeling approaches and the difficulties in making reliable settlement or permanent deformation estimates. The case of displacement demands on pile foundations arising from liquefaction induced lateral spreads, is also discussed, and illustrated with design examples.

The damage features of the spherical storage tanks at the time of the 1995 Kobe earthquake were introduced, together with the in-situ soil conditions. In an aim to clarify the cause of the distress, back-analysis was made for the foundation piles based on the three-layer model proposed previously. The results of the analysis disclosed that the bending moment near the pile head and at the depth of the boundary between the liquefied and the underlying unliquefied layer reached values close to or in excess of the moment at yielding or at failure of the pre-cast reinforced concrete piles.

The paper discusses the geodynamic challenges in high speed and high axle load railway projects, especially for soft ground conditions. Three main issues need to be solved by the engineering community: critical speed and excessive dynamic response of the track structure and supporting ground, accelerated degradation of the track structure, and vibration in track-side dwellings and buildings that can inconvenience people and disturb sensitive equipment. The paper describes the nature of these three issues and discusses the prediction tools and design strategies. The importance of knowledge on the ground characteristics, especially the dynamic properties, is emphasized. Countermeasures are discussed. Further needs are pointed out, including the most urgent needs for further research and development. The benefit of standardized solutions, international collaboration projects and the sharing of knowledge is highlighted.

The choice of a design concept for a bridge foundation is guided by various factors; several of these factors are indeed of technical origin, like the environmental conditions in a broad sense, but others non technical factors may also have a profound impact on the final design concept. The foundations solutions adopted for the Rion Antirion bridge are described and an attempt is made to pinpoint the major factors that have guided the final choices. The Rion Antirion bridge is exemplar in that respect: the foundation concept combines the simplicity of capacity design, the conceptual facility of construction and enhances the foundation safety. The design of these foundations was a very challenging task which required full cooperation and close interaction with all the parties involved: concessionaire, contractor, designers and design checker.

The 7,500 acre Port of Los Angeles is a major U.S. West Coast gateway for international commerce. Along its 35 miles of waterfront, the Port of Los Angeles has 28 major facilities specializing in automobile, breakbulk and containerized dry and liquid bulk cargo operations. This abstract includes some of the geotechnical challenges associated with the planning and design of the Pier 400 Mega-Container Terminal and the Transportation Corridor providing the infrastructures to the terminal. The Pier 400 container terminal is designed and constructed in two phases. Phase I comprises 343 acres including 4,000 feet of wharf, backland, terminal buildings and intermodal rail facility. Phase I included construction of the entire transportation corridor consisting of highway, rail and utilities. Phase II comprises an additional 141 acres including 3,190 feet of wharf, remaining backland and terminal buildings. The 484-acre Pier 400 container terminal is the world's largest proprietary container terminal. The facility features: Water depth of - 55 feet mllw at the wharf; 22 wide 100-foot gauge cranes; Up to 18 ship to shore cranes; 4 unit train loading yard (96–305 feet cars); 6 unit train storage yard (126–305 cars); and Gate complex & various terminal buildings.

Geotechnical studies for the replacement of the 4-km-long San Francisco-Oakland Bay Bridge (SFOBB) East Span included extensive over-water and onshore geophysical surveys, geologic mapping, and geotechnical explorations. The data collected from those studies were integrated to develop a comprehensive 3-D representation of the subsurface conditions along the chosen bridge alignment. This paper summarizes the geophysical surveys, geophysical data processing techniques, and the integration of the geophysical data with marine borings and CPT soundings. By comparing the seismic reflection data with downhole P- and S-wave velocity suspension logs, it was possible to accurately convert the time sections obtained from the geophysical surveys to depth sections despite the presence of gas-charged sediments infilling an extensive paleochannel system. The combined data also documented the lack of recent activity of several faults. All of the geophysical and geotechnical data were captured in a Geographic Information System (GIS) database. The GIS was used to shorten the overall timeframe for the site characterization and allowed project design to proceed concurrently with the geotechnical study.

This paper is part of a series of papers covering various aspects of the new East Span of the San Francisco-Oakland Bay Bridge. It will focus on the design of the self-anchored suspension span.

This paper presents development of seismic design criteria for the San Francisco-Oakland Bay Bridge (SFOBB) East Span Replacement Project. Probabilistic Seismic Hazard Analysis (PSHA) was used to establish the basic rock motion criteria; the 1,500-year and 92-year return periods were adopted for the Safety Evaluation Earthquake (SEE) and Functional Evaluation Earthquake (FEE) ground motions. The preliminary design of the bridge was conducted with a response spectrum approach and was checked against six sets of time histories. The ARS design curves and time histories used for dynamic analyses of the structure were derived from the considerations of wave propagation in soil sediments and soil-pile interactions. Near-fault directivity effects and incoherency of ground motions were considered.

The San Francisco-Oakland Bay Bridge is one of the most heavily traveled bridges in the world. The east span of the bridge will be replaced due to seismic safety concerns. The new bridge will be founded mostly on large 1.8 to 2.5-meter diameter, approximately 60- to 100-meter long pile foundations. Piles foundations will experience tension loads of up to approximately up to 90 MN and compression loads of up to approximately up to 140 MN during the design earthquake.

The east span of the 3.5 km long SF-Oakland Bay bridge is supported by different types of foundations along its span. Its first 460 m section comprising twin concrete box-girders is supported by sands and rock on Yerba Buena Island. A 620 m long steel suspension span then bridges a 25 m deep channel that is formed in sediments overlying rock. Twin concrete box girder structures, each 2.4 km long, complete the stretch over the remainder of San Francisco Bay to the engineered earth fill landing at its east end. For most of its length, the Skyway bridges water 3 to 10 m deep over soft surficial Young Bay Mud. The foundation types include spread footings with hold-downs, steel and concrete piles that are set in drilled rock sockets up to 3 m in diameter and 2.5 m diameter steel tubular piles driven to penetrations of up to 100 m. The design and construction-related considerations are presented. The different foundation types, influences of the site geology and earthquake demands on the substructures are discussed. The seismic motions of the bridge superstructures and substructures, as well as the depth-varying soil motions, influenced the foundation design. Together with performance-based design criteria, including post-earthquake footing displacement limits, these seismic demands influenced various aspects of the foundation design, including the use of battered and vertical piles.

This paper presents a brief summary of two aspects of soil-structure interaction studies conducted for the San Francisco-Oakland Bay Bridge East Span project. There was significant variability in the presence or absence of a very dense Merritt sand layer at shallow depths due to Paleochannel erosions of the Merritt sand strata. This resulted in the choice of battered pile groups for the skyway. A battered pile group has some advantages for the specific project condition. The SFOBB skyway contract is unique in the fact that the resultant design needs to be checked against both conventional response spectrum solution as well as time history solutions. A rigorous kinematic soil structure interaction (SSI) input motion approach was adopted in developing the theoretically rational acceleration response spectrum (ARS) criteria. This paper provides discussions of the kinematic SSI motion approach. Various site stability issues have surfaced historically at the Oakland Mole approach, due to the combination of poor soil condition and the relatively steep ground relief features at that location. Efforts were involved in the design to address potential ground movements and their implication to the Oakland Mole transition structures. The pinning effect of the large pile groups was found to be significant in stabilizing the ground against potential ground movements. This aspect is also addressed in this paper.

This paper describes the accelerated environmental processes undertaken for the San Francisco-Oakland Bay Bridge (SFOBB) East Span Seismic Safety Project by the California Department of Transportation (Caltrans). The environmental evaluation process is a planning tool, which may take five or more years for complex projects, and detailed engineering is typically performed after receiving environmental approval. Due to the seismic vulnerability of the existing structure, the State accelerated the environmental process. Through careful planning, the State performed environmental evaluations on several alternatives while simultaneously coordinating and partnering with external agencies, performing public outreach, and proceeding with engineering studies and (later) detailed design of one replacement alignment. The State risked that the alternative selected through the environmental process would be the same as that being designed, thereby cutting years from the schedule. These strategies paid off. The alternative selected through the environmental process was a replacement structure on the same alignment as the "risk design." The project is now under construction.

A variety of ground improvement methods were employed on the Geofill embankment to allow stable construction on soft, compressible clays and provide acceptable long-term performance. The paper presents a case study of the techniques used which included multiple geosynthetic layers to enhance construction, wick drains with surcharge fill to accelerate settlement and soil strength gain, vertical pipe drains to density existing sandy fill, and controlled rate of loading to maintain stability. Typical geotechnical monitoring and vertical pipe drain test section results are also presented. A summary of lessons learned from the successful construction is provided to assist practitioners on similar projects.

Upon its completion, the new Cooper River Bridge will have the longest cable stayed main span in North America. The project includes over 400 large diameter drilled shafts, three miles of elevated highway, and numerous embankments over poor foundation conditions. From a geotechnical perspective, there is a long list of design and construction challenges. Besides the large vertical foundation loads that may be expected for a bridge this size, a Charleston design earthquake of M 7.3 results in comparable lateral and overturning loads. The subsurface conditions include liquefiable sands and very soft, compressible marsh clays overlying the cemented soils of the Cooper Group. This paper provides a brief history and an introduction to the Cooper River Bridge. Its intent to familiarize the reader with the historical and technical significance of the project that is discussed in greater detail in the technical papers prepared for this conference by the engineers and seismologists responsible for the study and geotechnical-related design of the Cooper River Bridge.

The design for a major cable-stayed bridge under construction in seismically-active Charleston, South Carolina, included rock islands around the main span piers as protection from ship impact. Considering the historical seismic activity of the region, a primary concern was the potential for instability of the rock island slopes during a major earthquake. This paper compares results from modeling of the rock island and ship channel using the dynamic two-dimensional finite difference software FLAC to the results from conventional pseudo-static analysis.

Cooper River Bridge in Charleston, South Carolina has a length of approximately two miles (3.2 km), including a cable-stayed structure with a main span of 1,546 ft (471 m), approach structures and extensive interchange ramps on both sides of the crossing. These structures are supported by 405 drilled shafts with design capacities up to 11,000 kips (49 MN) and lengths as much as 237 ft (72 m). All drilled shafts are founded in the Cooper Marl formation. The paper documents the results from construction-stage Osterberg load tests and describes the design of these unusually deep, high capacity drilled shaft foundations.

At the expected time of its completion (2005), the new Cooper River Bridge in Charleston, South Carolina will be the longest cable-stayed bridge in the US. The $600+ million structure is supported on drilled shafts, which bear within the soils of the Cooper Group (colloquially known as the Cooper Marl). Geotechnical data necessary for foundation design were primarily obtained during three major site characterization programs performed for the preliminary design phases. The programs included soil test borings, cone penetration testing, shear wave velocity measurements, laboratory index testing, consolidation testing, and triaxial shear testing. The extensive data from these exploration efforts are summarized and evaluated. The Cooper Marl typically classifies as an overconsolidated (OCR of 3 to 6), highly plastic clay or silt with liquid limits often in excess of 100 and plasticity indices of more than 50. The fines content is generally in the range of 75% to 90% but the clay mineral content is small (<10%) and the primary mineral constituent is calcium carbonate (60% to 80%). The calcium carbonate content is mainly in the form of the skeletal remains of microscopic marine organisms (e.g., foraminifera) and the fossiliferous nature of the particles is thought to explain the fact that the effective friction angle is typically in the range of 43 to 46 degrees. The void ratio is relatively high (1 to 2) but the undrained shear strength is also high (140 kPa to 280 kPa) and the shear wave velocity (generally in the range of 400 m/s to 600 m/s) is relatively constant with depth; all of which indicate that the deposit is cemented.

The South Carolina Department of Transportation is replacing both the John P. Grace Memorial Bridge and the Silas N. Pearman Bridge with a new eight-lane long-span cable-stay bridge under a design-build contract. The project includes 5.6 kilometers (3.5 miles) of new structure for US17 and a cable-stay main span of 471 meters (1,546 feet) that will be the longest in North America when completed. This undertaking would have represented a challenge in a standard design-bid-build procurement because of the potential for both earthquakes and hurricanes in Charleston and the size of the project. The use of a design-build process complicated this further by requiring that the SCDOT develop sufficient geotechnical reports for the proposing contractors and set design criteria that would provide for the best bidding opportunity and minimize costs to the SCDOT. The procurement process used allowed the SCDOT to adapt the design criteria in the best way to achieve this goal. Like most other design-build contracts, this project emphasizes Contractor Quality Control as the primary method for inspection of the completed work. The SCDOT and the design-build contractor, during the construction phase, put in place processes that gave confidence that the work performed can be accepted by the SCDOT.

Design horizontal and vertical earthquake response spectra for the replacement Cooper River Bridge in Charleston, South Carolina were developed based on site-specific probabilistic and deterministic ground motion studies. Two basic analyses were completed to develop horizontal response spectra for soft rock conditions. The first was a probabilistic seismic hazard analysis (PSHA) for hard rock conditions. The information used to conduct the PSHA includes the characterization of seismic sources of significance to the bridge site and the characterization of ground motion attenuation relationships applicable to hard rock in the eastern United States. The second basic analysis conducted for the study was an analysis of crustal response to the hard rock motions. For this analysis, the response of soft rock extending from the top of hard rock at 800 m depth to the base of Cooper Marl at 100 m depth was evaluated. The presence of a thick, relatively low velocity soft rock layer having a strong velocity (impedance) contrast with the underlying hard rock resulted in a substantial amplification of long-period ground motions in the analysis. Two additional supporting analyses that were completed include development of deterministic response spectra and vertical response spectra.

This paper discusses the main aspects of the performance-based seismic design of the new Cooper River Bridge. Specifically, the discussions include the following subjects: (1) site response analysis; (2) soil-structural-foundation (interaction) modeling methodology; (3) 3-dimensional inelastic nonlinear time history analysis using spatially varying ground motions; (4) foundation design methodology to accommodate the potential for liquefaction and scour; (5) foundation design strategy to deal with the effect of lateral spread; and (6) performance-based seismic design of embankments.

Soil embankment settlement causes concrete approach slabs of bridges to lose their contacts and supports from the soil, which results in the deterioration of rideability of the bridge approach slab. To investigate the effect of embankment settlements on the performance of the approach slab, a 3-D finite element analysis was conducted in the present study, considering the interaction between the approach slab and the embankment soil, and consequently the separation of the slab and soil. The predicted internal moments of the approach slab provide design engineers with a scientific basis to properly design the approach slab considering different levels of embankment settlements. Current American Association of State Highway Transportation Officials (AASHTO) code specifications do not provide clear guidelines to design approach slabs considering the embankment settlements.

Nonlinear dynamic analyses using the finite element (FE) method are compared to the results of dynamic centrifuge model tests of pile-supported structures in liquefying sand profiles. The FE models utilized soil spring elements that connect pile elements to one- or two-dimensional meshes of a soil profile. Development and implementation of the soil spring material models in the OpenSees FE platform are described. Single element examples are used to illustrate the behavior of the soil and soil spring material models. Comparisons of FE analyses to centrifuge test data of pile-supported structures in liquefying sand profiles suggest that these FE methods can reasonably approximate the essential features of soil and structural response.

In order to capture all significant aspects in complex dynamic soil-structure interaction problems, nonlinear behavior of soil skeleton, pore water, and embedded structure should be modeled in a coupled manner. One such fully coupled procedure is presented in this paper to study the dynamic soil-structure interactions during seismic events. This procedure is implemented into a 2-dimensional finite element computer code, DYSAC2, and predictions made by DYSAC2 are validated using centrifuge test results. Reasonable comparisons are obtained between the DYSAC2 predictions and centrifuge tests results.

Ground deformation was monitored at the site of a 4m high trial embankment, as part of a highway construction project in Switzerland. The soil conditions included a complex stratification sequence with 7m of compressible soil located at shallow depth. The test embankment main purpose was to assess the magnitude of final settlement to be expected with the actual construction project. It served also as a benchmark to evaluate the applicability of various computation methods. The latter included classical one-dimensional consolidation theories and simplified numerical modeling of the trial embankment. In this paper, the site conditions, instrumentation program and performance of the embankment are described. The main features of the numerical model are summarized. Its outcome is compared to other methods of analysis and to observed deformation. Possible sources of discrepancy are discussed, including limitations of the simplified constitutive model and possible shortcomings of the instrumentation system.

Seismic soil-pile structure interaction (SSPSI) is a complex process involving several, simultaneously occurring and, sometimes compensating phenomena. To better appreciate SSPSI, the physical processes that occur when a pile supported structure is seismically loaded are first categorized into far-field effects, near field effects, and inertial effects. Far-field effects consist of pore-pressure generation, ground deformation and subsequent cyclic degradation. Near field effects include strain rate effects (soil-pile slippage), cyclic degradation, and gap-slap mechanism. The effect of each phenomenon on the axial t-z and lateral p-y response is then discussed.

This paper describes the formulation and validation of a new finite element model for 3-D analysis of pile-soil interaction problems. The proposed element is constructed by wrapping 4 slip elements around a 2-nodes flexural element. The 4 slip elements are to model the interface between soil and pile and the 2-node flexural element simulates the pile segment. This element will lead to an ease of use in the 3-D numerical analysis of soil-pile interaction problems with slip elements being built in one element and a significant reduction of numbers of system Degree of Freedom comparing to the conventional way of modelling pile with 20-noded brick elements. The element stiffness formulation is based on the weak formulation of virtual work principle with the internal equilibrium between pile and soil being governed by Euler's beam theory in lateral reaction. The FEM program using the proposed model was developed and verified and validated with analytical solutions and a simple case study.

The development of the arch was one of the most significant events in the history of structural design. Its value is apparent in the ability of the arch to transfer vertical loading into manageable compression loading. In the highway and industrial markets, arches have been developed as both precast and cast-in-place concrete structures used for bridges, tunnels, culverts and material containment igloos. A new technology called TechSpan^TM consists of segmental precast units forming a three-hinged arch structure. TechSpan utilizes the concept of a funicular curve. The term funicular is defined as "imitating a rope and its tension". This concept is used for the TechSpan design. This paper will discuss the analysis, design, and construction of TechSpan. The analysis involves use of a finite element soil-structural model, which allows flexibility in fitting various precast arch shapes to the needs of a project. Specific TechSpan projects will be discussed to demonstrate the relationship of analysis and design to the final construction of the arches.

Integral-abutment bridges (IABs) are a unique and interesting case study in soil-structure interaction. They were developed to solve long-term structural problems that occur with traditional bridge designs but, as an unanticipated result, created new problems of a geotechnical nature that manifest themselves only after an IAB is placed in service. One problem associated with IABs that tends to develop relatively rapidly is ground subsidence adjacent to abutments. This results in the classical `bump at the end of the bridge' or potential failure of the approach slab if one is used. The other IAB problem develops in the longer term and involves the irreversible buildup of lateral earth pressures on the abutments due to a soil-mechanics phenomenon called ratcheting. These pressures can lead to structural failure of the abutments. With the increased worldwide use of IABs in recent years, there is widespread interest in developing design solutions to the in-service deficiencies exhibited by IABs as they are designed currently. Fundamental to achieving this goal is developing a clear understanding of how and why the geotechnical problems develop. Research indicates that the primary cause of all problems is irreversible displacement of the soil retained by the abutments of IABs. Research also indicates that design solutions can be achieved using a variety of geosynthetics in an innovative, synergistic fashion. First and foremost, a self-stable zone of material must be established behind each abutment. This can be achieved using either a reinforced soil mass or some type of geofoam (EPS blocks or foamed concrete). Secondarily, an EPS-geofoam geocomposite must be placed between this stabilized zone and the back of the abutment to act as a compressible inclusion. This inclusion serves both as an expansion joint to accommodate seasonal displacement of the abutment as well as to provide insulated drainage. An important benefit is that these solutions can be implemented as part of either new construction or the rehabilitation of existing IABs.

Down-drag loads on pile foundations can be an important design consideration when earthquake-induced liquefaction is expected to cause ground settlements. A modified neutral plane solution for liquefaction-induced down-drag on vertical piles is described that accounts for the variation in excess pore pressures and ground settlements over time as a liquefied layer reconsolidates, the dependence of sand compressibility on excess pore pressure ratio, and the dependence of shaft skin friction on the excess pore pressure ratio. A worked example illustrates the role of various parameters on peak pile loads and settlements. The modified solution predicts substantially smaller pile settlements than obtained from a traditional neutral plane solution for end-of-consolidation conditions. Recommendations for design practice are presented.

The Missouri Department of Transportation (MoDOT) is currently reconstructing Interstate 70 through the City of St. Louis. As part of the reconstruction, numerous bridges are being replaced. The O'Fallon Park Drive Overpass was nearing completion in the Spring of 2002 when movement was observed in the slope adjacent to the southern bridge abutment. A geotechnical investigation was performed to characterize the subsurface conditions and evaluate the cause of the slide. Slope mitigation measures consisted of a multi-staged approach. As an interim repair, pipe aggregate drains (similar to french drains) were installed in the slope to intercept groundwater flowing downhill toward and within the slide mass. The final repair consists of a tied-back tangent pile wall and a rock shear key. The tangent pile wall consists of drilled shafts installed to bedrock connected with a grade beam beneath the new bridge. The grade beam contains tiebacks installed into the underlying bedrock. A rock-filled shear key with a drainage pipe will be constructed in the slope east of the new bridge.

Legacy Parkway is a proposed fully controlled access highway in Salt Lake/Davis Counties, Utah. The current Parkway alignment is located in the Lake Bonneville Basin. The near surface soils are composed of stream alluvium, lateral spread deposits, lacustrine silts and clays and marsh deposits. The geotechnical challenge along the proposed alignment includes settlements (both primary and secondary) in the range of few millimeters to upwards of 1000 millimeters over a period of time ranging from about 30 days to 2,000 days. The traditional approach of building the bridge embankments and allowing for the settlement to be complete before building the abutments would not allow the builder to meet the schedule constraints. A creative engineering approach, based on field data, helped accelerate the construction of bridge abutments before the settlements due to embankment loads were completed. This paper will present details of downdrag/dragloads on the bridge foundations due to settlements, analysis conducted, and the planned approach taken by the Design-Build Team to accelerate construction.

The increased use of integral abutment bridges in recent decades has preceded fundamental understanding of system behavior and development of design methods that appropriately account for controlling parameters. Due to its integral design, the influence of factors such as thermal expansion/contraction must be revisited as they have a dominant role in behavior. This paper summarizes the soil-structure interaction aspects of the south abutment performance of a 270-ft three-span integral abutment bridge in central Massachusetts. Continuous performance monitoring with an instrumentation array of 85 sensors is ongoing. A site investigation of the abutment backfill was performed to estimate the lateral earth pressures. The influence of thermal effects on the south abutment performance over one 12-month cycle that included temperature variations between –18°C and 38°C is presented.

The Howland Hook Marine Terminal (HHMT) is located along the Arthur Kill shipping channel on Staten Island in NYC. It is a vital port facility for the shipment of containerized cargo through the Port of New York to the East and Midwest markets. The existing terminal was built in the 1960's and was designed to accommodate vessels with drafts of 10.5 meters. The present redevelopment program involves the reconstruction of the existing wharf to accommodate 15-meter draft vessels, lengthening the wharf by 150 meters, and upland soil stabilization for increased container storage and a new inter-modal rail yard. Soil stabilization involved consolidating lime sludge lagoons and tidal marsh deposits, as well as the construction of a 25-hectare square meter reinforced soil sub-base (soil beam) over a former gypsum disposal area. The high bedrock and poor soil conditions on this project created significant geotechnical design challenges.

Design and construction of marine structures in weak foundation soils in a seismic environment constitutes a major challenge. Several ground improvement measures were employed in the design of the quay wall and breakwater of New Port of Patras to cope with extremely adverse geotechnical and earthquake conditions. Dictated by new findings during the construction phase of the project, significant modifications of the soil improvement designs were made, which led to enhancement of the static and seismic stability of the temporary and permanent structures, as well as to reduction in the overall construction time.

The largest single-user container terminal in North America was recently constructed on Pier 400 at the Port of Los Angeles. The terminal's 2,250-meter long wharf is supported by about 3,700 24-inch octagonal precast, prestressed concrete piles. The piles are about 35-meters long and were driven through between 3 and 16 meters of rock dike. A total of 55 piles were monitored during two indicator pile-driving programs to develop the appropriate pile driving criteria to obtain the required axial pile capacity. The pile driving indicator programs include: 1) data from two different size diesel hammers and one hydraulic hammer, 2) comparison of piles driven dry versus those driven with jetting, and 3) restrike data after several days, several weeks, and several months. The results of the indicator pile programs provide the opportunity to better appreciate: 1) the impacts on capacity and schedule, when the piles are jetted, 2) the validity of using short-term restrikes to evaluate the ultimate long-term capacity of the piles, and 3) the potential economic, schedule, and quality control advantages that can be obtained when a hydraulic hammer is used.

The AirTrain JFK light rail system, which services JFK International Airport, has a major mass transit connection at the existing Long Island Railroad (LIRR) Station in Jamaica, Queens. Constructing the new transit center adjacent to and above the operating LIRR station presented many challenges. Connection to the New York City Transit's (NYCTA) subway system and construction of a basement for the new transit center building required deep excavations adjacent to operating tracks. These excavations had to be accomplished in very confined work areas and executed without excessive lateral deflection. The AirTrain JFK transit center Mezzanine Bridge was constructed over 12 operating rail tracks. It is supported on relatively high capacity mini-piles drilled through the existing station platforms. Existing 100-year old, precast concrete piles were re-used to support reconstructed platforms and historically restored platform canopies. The main transportation building, which will ultimately be a seventeen-story mixed used office building, is founded on 1,900 kN (210 Ton) TaperTube piling.

This paper presents results of seismic soil-structure interaction (SSI) analyses of an underwater bulkhead and wharf system for the proposed Berth 145-146 Upgrade in the Port of Los Angeles (POLA), California, the first major undertaking of its kind at the POLA. The underwater bulkhead consists of strong center piles that are called king piles with sheet piles placed between them. The finite-difference computer program FLAC was used in the two-dimensional static and dynamic SSI analyses. To optimize the choice of king pile section and evaluate the effects of ground motions, the analyses focused on the behavior of the underwater bulkhead and wharf system for two king-pile configurations under three seismic motions. The seismic SSI analyses allowed selection of a smaller king-pile underwater bulkhead system compared with recommendations from simplified analyses, resulting in cost savings to the project.

As part of ongoing improvements at Hartsfield-Jackson Atlanta International Airport (HJAIA), a new 2,744m (9,000 feet) long Runway (10–28) and parallel Taxiway (U) are in the process of design and construction. The new runway/taxiway will be located 1,280m (4,200 feet) south of existing runway RW 9R/27L and will be connected to Taxiway R by new parallel Taxiways W and Z aligned in a north-south direction. Post, Buckley, Schuh & Jemigan (PBS&J) is the design engineer for the eastern portion of the runway which is approximately 1,067m (3,500 feet long). Willmer Engineering Inc. (Willmer) performed the geotechnical investigation and analyses for the eastern portion of the new runway/taxiway, two new north-south taxiways, a new non-licensed vehicle road (NLVR) tunnel and Loop Road tunnel to be constructed under the two new taxiways, and a mechanically stabilized earth (MSE) wall to retain a portion of the runway fill to permit a road alignment. For the eastern portion of the new runway/taxiway, as much as 21.3m (70 feet) of new fill will need to be placed over a residual soil profile with up to 15.3m (50 feet) of compressible thickness. The extensive site investigation revealed extremely variable subsurface soil conditions. Rock (auger refusal) was encountered at depths ranging from a few feet to almost 30.5m (100 feet) below existing grades. The combination of thick fills and variable thickness of compressible residual soils resulted in large differences in estimated total settlements and differential settlements along the alignment of the runway and taxiways. Another component of concern was the long-term settlement due to secondary consolidation of the residual soils under constant loading. It has been reported that certain portions of the existing taxiway system had experienced 203mm (8-inches) of settlement over a 20-year period. Long term settlements were a major issue regarding design grades along the runway and taxiways.

The project is associated with expansion of the Indianapolis International Airport, which will require realignment and depression of a section of interstate I-70 for construction of an airplane taxiway over the road. The geotechnical investigation encountered three distinct water-bearing units, including a confined sand and gravel aquifer which was expected to be a significant source of discharge. Design of an appropriate underdrainage system to maintain pavement integrity was supported by a hydrogeologic investigation. Data from the hydrogeologic investigation, geotechnical investigation, and underdrainage design specifications were then modeled to predict groundwater inflows to the drainage system. Subsequently, collection of dewatering discharge volume information during roadcut excavation provided an opportunity for a critical evaluation of the model results.

The railroad system of the largest steel manufacturer in Taiwan has been in operation over the past ten years. It affords mainly the transportation of heavy furnace liquid steel. Due to the extremely heavy load and frequently cyclic loading, serious pumping problems had appeared along the rails, and resulted in aggressive ground settlements and distortion of rails. In an attempt to solve such engineering problem, the authors first conducted an extensive soil investigation and monitoring program to identify the failure mechanism. Geosynthetics applications of separation and reinforcement were then proposed as solutions to the observed engineering problems. In order to verify the proposed designs, the authors also execute a test sections plan to evaluate performance of different geosynthetics designs. In this paper, process and results of soil investigation and test section evaluation are presented. Instrumentation measurements obtained four months after the test section installation imply that the proposed mitigation methods have provided a feasible solution to the railroad pumping problems under extremely excessive cyclic loads.

Expanded Polystyrene Geofoam lightweight fill was used to mitigate settlement of bridge approach embankments constructed over compressible silty clay soils. Three settlement mitigation alternatives were considered: no mitigation measures; wick drains with surcharge; and EPS geofoam lightweight fill. Lightweight fill was selected in order to meet the very aggressive project schedule. The lightweight material was proportioned to limit post-construction differential settlements to 6 inches between the pile-supported bridge and earth-supported approach embankments, and to 3 inches or less from one side to the other of the 30-foot wide approach slab. An HDPE protective membrane system was installed to protect the geofoam from fuel spills. Settlements measured using conventional settlement platforms are compared to estimated settlements.

Theoretical studies have been performed for drainage and filtration characteristics, low consolidation rate of sand mat and prefabricated horizontal and vertical drains. These prefabricated horizontal drains were adopted to substitute for sand mat in domestic highway construction sites and test instrumentation was installed to investigate the drainage and filtration capacities of these materials. Finally, discussion on quality control and methodology is presented.

This paper describes a 10-ft high steel sheet-pile wall backfilled with geogrid-reinforced geofoam (expanded polystyrene-EPS) within a peat marsh. The wall and reinforced lightweight fill were used to reduce global stability concerns, reduce long term settlement of the new roadway lane, and to reduce impact to adjacent wetlands. The wall backfill settlement and two inclinometers attached to the full length of the steel sheeting in the critical wall section were monitored during construction. Using simple beam theory and inclinometer data, the moments in the sheeting associated with the deflection profiles are calculated. Pressure diagrams for each inclinometer location are back-calculated based on the observed moment diagrams. Design implications inferred by the back-calculated pressure diagrams are discussed. Wall backfill settlements up to about 6 inches were measured during construction. Lateral displacements at the top of sheeting reached about 2 inches to 3 inches with a 2.5-ft thick aggregate pre-load surcharge in place. Back-calculated pressure diagrams indicate the otherwise highly compressible peat marsh deposits behaved for a short period like a high viscosity fluid supporting the weight of the existing and new fill. Comparison of two adjacent inclinometers gives insight into some three-dimensional behavior in the wall.

The thrust force generated due to internal water pressure in a pipe tends to move the bend of underground pipeline to the backside. This thrust force is supported by the passive soil pressure at the back of the ground. The thrust force is commonly resisted by the concrete block at the bend. The earth pressure distribution at the back of the ground as the pipe moves laterally is not readily known. In addition, concrete block is not desired in the event of earthquakes because of its inertia force to move. In this paper, pit tests were conducted using a model pipe having a diameter of 90 mm in a dry sandy ground. Geosynthetic was used as anchor to resist the movement of the pipe. In addition, similar tests were conducted using a model pipe of square surface assuming it as a concrete block. The resisting force acting on the model pipe and the earth pressure in the sand ground were measured as the pipe moved horizontally in the ground. The development of slip surface in the backfill ground surface was also investigated. The test results showed that proposed lightweight method that used geosynthetic had significant effect in improving the resistance against thrust force.

The classical railway track basically consists of a flat framework made up of rails and sleepers, which are supported on ballasted track formation. Ballast particles breakdown and deteriorate progressively under heavy cyclic rail loading. Moreover, excessive consolidation settlement and progressive shear failure may occur in soft track formation under repetitive stresses. In order to rectify these problems, frequent maintenance operations are generally required in ballasted track. In order to minimize the deterioration of track substructure and also to reduce maintenance cost, the use of various types of geosynthetics including recycling of waste ballast have been studied in the laboratory. The prospective use of three types of geosynthetics (i.e. geogrids, geotextiles and geocomposites) in enhancing the performance of fresh and recycled ballast has been examined. The aspects of deformation and degradation of ballast under cyclic loading have been studied using a large-scale prismoidal triaxial rig. The research findings reveal that recycled ballast stabilized with geosynthetic reinforcement has a good potential for resilient track construction and for reducing the cost of track maintenance. The experimental findings may be beneficial to the railway engineers and encourage them to upgrade current tracks based on these innovative techniques.

Cellular geosynthetics is the generic term for geosynthetic materials and products with either a closed- or open-cell texture. This includes the product categories of geofoams and geocombs that are the focus of this paper. Cellular geosynthetics have begun to have a noticeable impact in engineered construction, especially transportation applications. This is because they offer a wide range of geosynthetic functions that, with few exceptions, are unavailable from traditional planar geosynthetics such as geogrids, geomembranes and geotextiles. This paper summarizes the geofoam and geocomb materials and products that are available currently, and highlights their functions and typical applications on transportation-related projects with an emphasis on new trends and developments.

The application of the polymeric reinforcement in the construction of steep reinforced slopes is becoming more common. The mechanisms of failure of these reinforced slopes from internal stability point of view are especially due to: (i) rupture of reinforcement layers and (ii) pull-out failure along the soil-geotextile interface. In this paper these particular failure mechanisms are investigated. Centrifuge tests were carried out on model geotextile reinforced sand slopes at the newly commissioned Beam Centrifuge Facility at Indian Institute of Technology Bombay. The lateral displacements of the geotextile reinforced slope and the surface settlement of slope were monitored using LVDT's. Further, the strain distribution along reinforcement layers was analyzed and interpreted. The centrifuge test results were found to give valid information about the behaviour of geotextile reinforced slopes at failure.

This paper presents the results of an investigation on the behavior of geosynthetic-reinforced segmental retaining walls in tiered arrangement. A finite element model capable of modeling the fundamental behavior of geosynthetic-reinforced segmental retaining wall was used to perform a parametric study. Primary variables considered in the parametric study include the offset distance between the tiers and the reinforcement length in the lower tier. The results of the parametric study were then used to highlight the interaction mechanism between the upper and the lowers. Practical implications of the findings from this study are discussed in great detail.

This paper presents results from numerical study to investigate the interactions between rammed aggregate piers and geosynthetic reinforcement in pier-supported embankments. The investigation was conducted using a two-dimensional, plane-strain, finite element model. Linear elastic, perfectly plastic constitutive model parameters were assumed for the rammed aggregate piers, the matrix soil, the embankment fill, and the aggregate blanket. In addition to several pier-soil stiffness ratios considered in the analyses, a range of center-to-center spacings between piers was included. The geosynthetic reinforcement was modeled as a tensile element with various tensile stiffness values. Results obtained from this study provide insight into: (1) the interaction between the pier elements and the geosynthetic reinforcement to reduce differential settlement; (2) range of stress concentration ratio; and (3) tensile force developed in the geosynthetic reinforcement. It is concluded that the efficiency of using geosynthetic reinforcement is improved as both the geosynthetic modulus and the pier-soil stiffness ratio increase.

This invited paper presents a complete reliability calibration for drilled shafts subjected to undrained lateral-moment loading. The main purpose is to demonstrate that key RBD components are in place and it is practical to achieve close integration with structural RBD, without minimizing important geotechnical considerations such as soil variabilities.

The influence of sample size, and insitu test device variability on the computed LRFD axial resistance factors, φ, for driven piles is investigated. Specifically, the variability in LRFD resistance factors, φ, is shown to be directly related to both the size and statistics (bias, and standard deviation) of the measured/predicted axial pile/shaft database using Monte Carlo simulations. Similarly, it is revealed that a pile capacity predicted variability may be lower than the variability introduced through the use of insitu device strength correlations. Both the database size and insitu strength correlation variability may explain the lower LRFD resistance factors, φ obtained from databases than through fitting with ASD Factors of Safety.

This paper presents an evaluation of eight cone penetration test (CPT) methods and the static α-method to determine the load and resistance factor design (LRFD) input parameters for single driven piles. Evaluation of these methods was conducted based on load test database of thirty-four square precast prestressed concrete (PPC) driven friction piles tested to failure. Resistance factors for the investigated CPT methods and the static α-method were determined using reliability-based analysis. Other design input parameters were determined based on the AASHTO LRFD design specifications for bridge substructure. Based on the results of the analysis, the Penpile method showed the highest values of resistance factors while Tumay and Fakhroo and Schmertmann methods showed the lowest values of resistance factors.

A comparison of three different models using back-propagation neural network for estimation of pile bearing capacity from dynamic stress wave data was made. The bearing capacity predicted by TNOWAVE was employed as the desired output in training. The study shows that the neural network models generally predict total bearing capacity more favorably if both the stress wave data and the properties of the driven pile are considered as the input parameters. In addition, better selection of input parameters rather than the increase number of input parameters will improve the accuracy of the prediction.

High-strain dynamic pile testing is an important tool for driveability analysis, but the major objective of dynamic testing is determination of pile capacity at the time of testing. This method is a convenient tool in the pile driving industry. However, though high-strain dynamic pile testing has been used in practice for years, the actual accuracy and the area of application of this method, and also understanding the results of dynamic pile testing are vague. The paper presents discrepancies in high-strain dynamic pile testing, some uncertainty in the CAPWAP signal matching, negligible effects of soil properties on the CAPWAP results, incorrect interpretation and misleading use of testing results. It is shown the necessity to use engineering principles for verification of high-strain dynamic pile testing.

U.S. industries annually generate millions of metric tons of solid by-products, and most of these materials have been landfilled at considerable cost since the inception of modern environmental regulations in the late 1970s and early 1980s. Recently there has been a shift in societal attitudes resulting in strong interest in developing beneficial re-use markets for industrial by-products. As a result, environmental regulations have changed and beneficial re-use of industrial by-products is now permissible in a variety of applications. Blast furnace slag, fly ash, bottom ash, boiler slag, reclaimed pavement materials, coal waste, and many other industrial by-products have been or are in the process of being beneficially used as construction materials. The transportation, construction, and environmental industries have the greatest potential for re-use because they use vast quantities of earthen materials annually. Replacement of natural soils, aggregates, and cements with solid industrial by-products is highly desirable. In some cases, a by-product is inferior to traditional earthen materials, but its lower cost makes it an attractive alternative if adequate performance can be obtained. In other cases, a by-product may have attributes superior to those of traditional earthen materials. Select materials are also added to industrial by-products to generate a material with well-controlled and superior properties. This paper describes beneficial reuse applications in the gray iron foundry industry that has been investigated at the University of Wisconsin-Madison. These applications include embankments, retaining walls, sub-base, flowable fills, barrier layers, and HMA mixtures.

Surficial slope failures, or nuisance slides, constitute a significant economic and manpower burden for many transportation agencies due to the frequent and recurring nature of the slides. A new method for stabilizing surficial slides using reinforcement manufactured from recycled plastics is being developed to provide agencies with a cost-effective alternative for stabilizing these slopes. As a part of this development, a design procedure has been established that draws upon previous experience with more conventional reinforcing materials such as concrete and steel, but with modifications to account for the reduced strength and stiffness of plastics. The design method follows a limit state design approach wherein a number of different limit states are considered, including failure of the reinforcing members, to establish the resisting force provided by the reinforcement. In this paper, the general design method is presented followed by more detailed coverage of each of the specific limit states that are considered in the design. Several design issues that remain to be addressed are also discussed.

This paper reports on a laboratory study to evaluate the feasibility of using crushed glass to improve the engineering characteristics of fine-grained, marginal materials (e.g. kaolin, quarry fines) and conversely, to explore the extent to which soil blending could enhance the cohesive behavior of crushed glass (CG). Several basic physical and mechanical properties of two different soil-glass blends were evaluated. The results indicated that the cohesive strength of the CG was increased by 50% to 100% by the addition of fine-grained soils; however, this was accompanied by a 20% to 45% reduction in frictional strength. When considering the addition of CG to marginal soils to improve their strength characteristics, the results show a significant amount of frictional strength was added to the fine grained soils through addition of CG.

In the Spring of 2002 the Maine Department of Transportation completed the rehabilitation of the Mud Pond Inlet Bridge. The project consisted of raising the grade of a timber structure with tire shreds. The bridge is located on the only route to the East Shore of Pushaw Lake, where 50 families reside year-round. The bridge over-topped with 600 mm of water during the Spring runoff. The design consisted of raising the grade at the driving surface using 600 mm of tire shreds. Compression test results were used to determine a tire shred unit weight after construction of 0.76 Mg/m³ and the required amount of overbuild of 60 mm. At-rest earth conditions and equivalent fluid pressure methods were used to design a permanent, timber lagging retaining system. Staged-construction plans utilized a temporary, geotextile wrap wall, designed using active earth pressure conditions. The $1.3 million final cost saved 87% over replacement alternatives.

Groundborne vibration reduction for rapid transit tracks usually takes the form of some type of "soft" or "special" track fastener, or a type of isolation system built under or incorporated as part of the track structure. These mitigation measures are for the reduction of vibration annoyance. Due to the great abundance of scrap tires, which can be shredded, an investigation was undertaken to determine what vibration attenuation properties are characteristic of tire shreds and how tire shreds would attenuate groundborne vibration. Two sets of field tests were performed to determine the vibration attenuation and damping properties of tire shreds for potential use beneath rail lines and other possible applications. The first set of tests was without rail and included three mobile vibration sources and one stationary impact vibration source. The second set of tests was performed using a short test and control section where the shredded tires were installed under ballast and tie rail transit track. Overall, the use of shredded tires as an underlayment beneath ballast and tie track as a means for reducing groundborne vibration appears to be both practical and viable in addition to finding an additional use for scrap tires.

In this paper we present the development of an elastic-plastic material model for tire shreds material. In particular, our aim is to use large scale triaxial tests to calibrate the elastic and elastic-plastic model for this anisotropic material. The main effort is focused on the dynamic behavior of tire shred material and in particular the energy dissipation characteristics during dynamic (seismic) loading. This paper presents results of a material model calibration using wave propagation tests on a triaxially loaded tire shred specimen. The immediate goal of the presented work is the creation of a verified and validated elastic-plastic material model that will then be used in numerical assessment of seismic behavior of bridge abutments. The validation procedure will ultimately include simulations of two bridge abutments made of tire shreds performed using a large centrifuge facility at UC Davis.

The program of "Next Generation of ground-motion Attenuation models" (NGA) is a partnered research program between the PEER-Lifelines program (PEER-LL), U.S. Geological Survey (USGS), and Southern California Earthquake Center (SCEC). The goal of the NGA program is the development of several scientifically based attenuation relationships having less variability and more reliable predictions of ground motions for use in engineering design practice. The current phase of the NGA program focuses on the use of empirical ground-motion data, with theoretically simulated ground motions guiding the selection of functional forms and the extrapolation outside the region of empirical data. Five developer teams were invited to participate in the concurrent development of attenuation models. In support of these developers, the NGA program also undertakes a series of closely coordinated seismological and geotechnical research projects. Six working groups are organized to conduct, review, and evaluate these research results. Members of the six working groups cover diverse expertise in strong-motion record processing, earthquake source/path effects, site classification and site response, and statistical analysis. Highlights of the NGA program and selected achievements are presented in this paper.

A Design Ground Motion Library (DGML) is being developed that will contain selected recorded acceleration time histories considered to be suitable for use by engineering practitioners for the time history dynamic analysis of various facility types in California and other parts of the Western United States. The DGML will include: (1) the electronic library of selected time histories and their associated ground motion parameters and supporting information on the earthquake source, travel path, and site characteristics; and (2) guidelines for scaling sets of time histories for applications. The characteristics of the seismic environment, including earthquake magnitude, faulting mechanism, source-to-site distance, near-fault directivity conditions, and site conditions, and the damaging characteristics of time histories are being incorporated into criteria for selecting and binning records for the library.

We present fault displacement data, regressions, and a methodology to calculate in both a probabilistic and deterministic framework the fault rupture hazard for strike-slip faults. To assess this hazard we consider: (1) the size of the earthquake and probability that it will rupture to the surface, (2) the rate of all potential earthquakes on the fault (3) the distance of the site along and from the mapped fault, (4) the complexity of the fault and quality of the fault mapping, (5) the size of the structure that will be placed at the site, and (6) the potential and size of displacements along or near the fault. Probabilistic fault rupture hazard analysis should be an important consideration in design of structures or lifelines that are located within about 50m of well-mapped active faults.

This paper describes part of a project to assess the feasibility of producing regional (1:24,000-scale) liquefaction hazard maps that are based on potential liquefaction-induced deformation. The study area is the central Santa Clara Valley, at the south end of San Francisco Bay in Central California. The information collected and used includes: a) detailed Quaternary geological mapping, b) over 650 geotechnical borings, c) probabilistic earthquake shaking information, and d) ground-water levels. Predictions of strain can be made using either empirical formulations or numerical simulations. In this project lateral spread displacements are estimated and new empirical relations to estimate future volumetric and shear strain are used. Geotechnical boring data to are used to: (a) develop isopach maps showing the thickness of sediment that is likely to liquefy and deform under earthquake shaking; and (b) assess the variability in engineering properties within and between geologic map units. Preliminary results reveal that late Holocene deposits are likely to experience the greatest liquefaction-induced strains, while Holocene and late Pleistocene deposits are likely to experience significantly less horizontal and vertical strain in future earthquakes. Development of maps based on these analyses is feasible.

Probabilistic seismic hazard analysis (PSHA) has become a fundamental tool in assessing seismic hazards and for estimating seismic design and seismic safety evaluation ground motions both on a site-specific basis for important and critical facilities and a national scale for building codes. A project to test and validate the numerical approaches and software used in PSHA was performed through sponsorship of the Pacific Earthquake Engineering Research (PEER) Center's Lifeline Program. A Working Group was organized and each member tested their own computer code in two sets of tests. Through several iterations, all codes were tested and acceptable answers were established either through analytical solutions or as the consensus answer from the test case results. The validation tests will be made available to any PSHA code developer/user worldwide through publications and the PEER website. The test cases will be used as a standard validation for all PSHA codes to be used in projects for the PEER Lifeline Program sponsors, which include the California Department of Transportation (CALTRANS), Pacific Gas & Electric Company (PG&E), and the California Energy Commission (CEC).

This paper presents the findings and recommendations of the User Scenario Work Group (USWG) in identifying a baseline of current practices within the geo-professional community and prioritizing desired functional requirements in the development of a comprehensive geotechnical information management system. This work was conducted as an initial phase of a larger project to demonstrate the effectiveness of a web based virtual data center for the dissemination of geotechnical data from multiple linked databases of various government and private sector organizations. An online survey was administered over the course of several months to practitioners across the nation. The results from the survey were compiled and examined to provide direction to the other project teams in the development of user-driven prototype data system.

A pilot system for archiving and web dissemination of geotechnical data collected and stored by various agencies is currently under development. Part of the scope of this project, sponsored by the Consortium of Organizations for Strong-Motion Observation Systems (COSMOS) and by the Pacific Earthquake Engineering Research Center (PEER) Lifelines Program, is the development of a data dictionary and formatting standard. This paper presents the data model along with the basic structure of the data dictionary tables for this pilot system.

A project supported by the PEER-Lifelines Program is currently finalizing a pilot system architecture supporting web-based interfaces capable of providing access to publicly available geotechnical data sets. This paper describes the pilot system architecture design developed by the project's Virtual Data Center Work Group (VDCWG). The design is based on the results of a geotechnical data use and user scenario survey and a data dictionary developed by the project's User Scenario Work Group (USWG) and Data Dictionary Work Group (DDWG) respectively. The design allows multiple data providers to make their data available through a uniform web interface, while each retains possession and control of their data. A user is able to view and download data from multiple organizations in a uniform file format. Over the long-term, the main objective is to extend the pilot system and link multiple databases of government agencies, universities and private companies. A workshop planned for June 21 – 23, 2004, will review the system to obtain input and consensus from the geotechnical community. The workshop proceedings will serve as a future implementation plan for expansion into a large-scale web portal.

The California Geological Survey (CGS) is implementing a user-friendly, GIS-enabled Web portal on the Internet for the dissemination of geotechnical data to researchers, governments, and the geotechnical consulting profession. Over 20,000 geotechnical borings throughout the greater Los Angeles and San Francisco Bay regions have been acquired over the past 10 years in support of regional assessments of earthquake-induced ground failure hazard. Results of these analyses form the basis for delineating regulatory hazard zones that local government must use to improve the earthquake resistance of new construction. Borehole data include lithologic logs, index properties, and results from a variety of other in situ and laboratory tests. Boring logs were acquired during decades of building and infrastructure development and were obtained from local building departments, flood control districts, highway departments and consulting firms. To navigate through the vast boring repository the CGS developed a map-oriented graphical interface, which facilitates identification of available data for particular sites of interest. Maps can be quickly generated by making a selection from either 7.5-minute USGS quadrangle or by dropdown lists of county, city, or zip code. Borehole locations can then be posted on the map view and when interactively selected the borehole metadata is displayed in a pop-up table. From the pop-up table the user can download the geotechnical data for the selected borehole. The user can also select multiple boreholes within a specific area either by selecting a quadrangle boundary, or by interactively defining a point on the map and associated radius of interest. The resulting report allows the user to view the individual records from the selection, and/or download all records into Excel format. The individual CGS database tables are represented as separate sheets in the Excel spreadsheet, and include the CGS data dictionary, and entity relationships.

An Internet-based, adaptive translative Geotechnical Database Management System (GDBMS) Framework was designed, developed and implemented to facilitate accessing and utilizing historical and current geotechnical data specific to the Virginia Department of Transportation's (VDOT) Hampton Road Third Crossing (HR3X) project. Hampton Road Third Crossing (HR3X) project is aimed to relieve congestion at the existing Interstate 64 Hampton Roads Bridge Tunnel in Norfolk, Virginia. The GDBMS utilizes an Internet-based GIS server for its interface and for easy data access. Source geotechnical data were compiled from existing and current VDOT geotechnical data and U.S. Army Corps of Engineers (USACE) existing Craney Island Dredged Material Management Area (CIDDMA) geotechnical data in a gINT® or equivalent format. Geotechnical data were then overlayed by USGS color digital orthophotographs. Typical GIS applications require all the pertinent data to be explicitly included in the GIS spatial database, and are mainly used for retrieval and display of such data. However, in contrast, the GDBMS framework implementation is largely based on an adaptive translative framework concept to allow actual geotechnical data to be used "as-is" without preparing them for the GIS spatial database, therefore provides a rapid implementation. The adaptive translative portion of the GDBMS framework automatically identifies type and characteristic of the "as-is" geotechnical data and subsequent translates it to various output data formats such as boring, STP, CPT, DMT, VibraCore logs, gINT project file, Excel CSV format, etc. and makes it available to the users via standard web browser interfaces. Thus effectively eliminates the need for costly retrofitting of existing geotechnical data. Furthermore, the GDBMS framework facilitates additional design and analysis capabilities including dynamic fence diagram generation over the Internet. The adaptive translative GDBMS framework was implemented based on the open system architecture principle with standard XML, Php, Javascript programming languages to ensure flexibility, expandability and scalability of the framework.

A prototype simulation tool has been developed which provides a web-based, interactive, user-friendly, finite element analysis capability. Though closely coupled to experiment design for a NEES-sponsored test facility in Southern California, the simulation tool can be thought of in general terms as a framework for the remote computation and visualization of finite element results. The development of the prototype simulation tool is based upon the Model-View-Controller design pattern, and the project is based upon an open-source, platform independent philosophy that facilitates the adaptation and distribution of the tools developed. The simulation tool can be accessed at http://nees.usc.edu.

This paper discusses the creation of multi-media CDs to assist civil engineers in design and construction of highways with recognition of the increasingly stringent requirements laid out by the Endangered Species Act (ESA). Under FHWA sponsorship Portland State University was required to study the possible marriage of computer learning technologies; using videographers, animators, and software designers, to the real world engineering design and site `feel' of construction activity using environmental construction experts on camera, and to include case histories. The result is a 100% digital and portable CD product with multi-media techniques designed to supplement more cumbersome paper and written word formats. This offers a new way to overcome civil discipline barriers, and with web on-line components quickly connect the engineer to current information, ensuring the CD is never outdated. The paper introduces and defines the 3 possible categories for this media technique to build future digital civil engineering libraries: Category I, II and III, each having different learning methodologies and formats.

Geographic Information Systems (GIS) are powerful tools for organizing, analyzing, and presenting spatial data. GIS can be used by geotechnical engineers to aid the various stages of design, from preliminary corridor geotechnical site evaluation through final geotechnical design. This paper briefly introduces GIS, how the technology can be applied, and discusses the benefits of its use in design. To illustrate these applications actual projects utilizing GIS are presented and discussed. GIS tools can be used to integrate existing data such as soil survey maps and aerial photos with project specific data; identify potential geological hazards; plan and track field work; catalog and review sampling and laboratory testing results; create maps and figures for reports; and improve communication between office and field staff, consultants and their clients, and project team members. These tools can help identify potential barriers to project completion early in the design process that may help to avoid costly redesign later on.

The application of information technology and systems and network approach will help advance the state of the art in the field of Geotechnical Engineering. Compilation of relevant data in a robust database, supported by appropriate design and analysis tools, promotes design automation and cost reduction. The use of open standards-based technology, portable across hardware platforms, web servers, application servers, etc., will provide Internet users with secure, reliable, and scalable applications. Consultants, research and development professionals, and regulatory agencies will benefit from a web-based geotechnical engineering tool. A knowledge-based technology will promote global awareness and information exchange.

The California High Speed Train Authority, created by the state Legislature in 1996, plans to provide more than 42 million annual commuters with a means of cross-state travel, reduce highway demands, and improve air quality by creating a statewide High Speed Train (HST) system. The HST will be a 200+ mph (320 km/hr) steel wheel, electric system traveling 750 miles (1200 km) on at-grade, elevated, and underground steel track rails, extending from Southern to Northern California in about 2.5 hours. A backbone infrastructure system of this nature is highly sensitive to environmental factors and requires cautious examination and planning, especially given California's complex geology and seismic activity. Geologic and seismic studies were performed as part of the Program Level Environmental Impact Statement (EIS) for the proposed statewide using a Geographic Information System (GIS). GIS was used to compare statewide geologic and seismic data for the various alternatives. GIS data included geologic formations, active faults, ground motion, soils, oil and gas fields, and mineral resources. Active fault crossings, areas of high ground motion, unstable formations, and large landslides were avoided by realignment where feasible. Tunnel sections were realigned to avoid fault crossings at depth. Mitigation of at-grade active fault crossings and associated ground motion will include speed reduction at crossing and modern ground motion sensors use SCADA (Supervisory Control and Data Acquisition) systems to reduce the possibility of derailment. A request for appropriation of statewide funds for the first segment of the HST project will be placed on the November 2004 ballot for Californians to vote on their future transportation system.

An evaluation of the Light Falling Weight Deflectometer (LFWD) device to reliably measure the in-situ elastic modulus of pavement layers and subgrades is presented in this paper. For this purpose, field tests were conducted on selected highway sections from different projects within Louisiana. In addition, six test sections were constructed and tested at the Louisiana Transportation Research Center (LTRC) Pavement Research Facility (PRF) site. All sections were tested using the Prima 100 model - LFWD in companion with other standard tests including the Falling Weight Deflectometer (FWD) and the Plate Load Test (PLT) that were used as reference measurements. Regression analyses were conducted to determine the best correlations between the elastic modulus obtained from LFWD and those obtained from FWD and PLT tests. Good correlations were obtained, which demonstrated that the LFWD can be a promising device for in-situ characterizing of highway layers and subgrades.

Some polymer systems are being increasingly used in asphalt concrete pavements because of their role in reducing several types of pavement distress and enhancing pavement performance. The Michigan Department of Transportation sponsored a research program to investigate the micro and macro-structural, morphological, and engineering properties of polymer modified asphalt binders (PMA) and mixtures. This paper presents the interaction of the rheological, morphological and adhesive properties of binders to the engineering properties of asphalt mixtures modified with five different polymers. The rheological and adhesive properties of binders and the elastic, fatigue, tensile, and permanent deformation properties of PMA mixtures were studied. It was found that the improvements in the structural and engineering properties of PMA mixtures are due to improvements in the rheological, morphology and binder-aggregate adhesion properties of binders. Some PMA systems show better resistance to fatigue cracking and rut potential than others. Two PMA systems were more effective in reducing the low temperature cracking relative to other systems.

Design and analysis of flexible pavement systems depend on soil layer characterization, traffic loads and number of passes. Currently, the AASHTO uses resilient characteristics of subsoils to characterize and determine the structural support of each layer and then design the layer thickness. Resilient properties are used in the characterization since they are assumed to account for plastic deformation of subsoils. This assumption is known to provide misleading characterizations in mixed soils. Hence, there is an important research need to evaluate the plastic deformation behaviors of subsoils. A research study was initiated to establish a test procedure to measure plastic strain potentials of subgrade soils using a repeated load triaxial device. This test was performed for 10,000 cycles to monitor the plastic strains. This paper presents these test results conducted on sandy clay. Effects of compaction moisture content, confining pressure and deviatoric stresses on the plastic strains of soils are addressed. A case study was used to explain the significance of plastic deformation measurements of soils in their overall contribution to rutting.

A laboratory study was undertaken to evaluate the behavior of a low quality aggregate base stabilized with Class C fly ash (CFA) under cyclic and static flexural loading to evaluate its resilient modulus (Mr) and flexural strength (FS), respectively. Prismatic specimens were molded and cured for 1 hour, 3 days, and 28 days. To evaluate the effect of CFA on the flexural strength two raw beams were molded using unstabilized aggregate. However, both of these beams could not be tested since they failed under their self weights, due to negligible flexural strength. Results of the stabilized aggregate specimens show that the FS and Mr values for cured specimens increased as the curing time increased from 1 hour to 28 days. However, the percent increase in those properties as curing time increased from 1 hour to 3 days is higher than the corresponding percent increase from 3 to 28 days. Such an increase is due to the formation of cementitious products. The resilient modulus in flexure decreased as the flexural stress increased due to large strain levels in a flexural test. Comparatively, the resilient modulus in compression increased with the deviatoric stress. The FS was approximately 8 to 10 times lower than the unconfined compressive strength. Knowledge of such differences in behavior may be of vital importance in designing flexible pavements having a stabilized aggregate base.

Crushed concrete (CC) and recycled asphalt pavement (RAP) are sometimes used as substitute fill material in retaining wall and pavement applications. The accuracy of the nuclear gauge device for density and moisture content measurements on these two recycled materials may be unreliable, due to their chemical compositions being different than typical earth fill. An experimental study was initiated to compare moist density and water content measured from the nuclear gauge with those from traditional rubber balloon and test pit methods. Test results show that the nuclear gauge consistently measured larger moist densities than the rubber balloon method for all materials tested. However, the discrepancies were most likely due to the inadequate size of the hole used in the rubber balloon test relative to the maximum particle size of the materials. This result was confirmed with test pit measurements, which showed closer correspondence with the nuclear gauge results. Water content measurements indicate that the nuclear gauge reports larger values of moisture content than oven drying for CC and RAP. This difference can be attributed to the misinterpretation by the nuclear gauge of inherit hydrogen atoms in CC and RAP as water molecules.

In many current procedures for structural design of pavements, an accurate determination of layer moduli is required. With the onset of the movement toward the 2002 Mechanistic Pavement Design, investigating the feasibility of supplanting the existing methods with more mechanistic approaches would be desirable. Nondestructive testing techniques are widely used to determine moduli of pavements, the critical strains and, thus, to estimate the remaining lives of pavement systems. A nondestructive testing device, the Seismic Pavement Analyzer (SPA), whose operating principle is based on generating and detecting seismic waves in a layered medium can be used for this purpose. Seismic methods provide fundamentally-correct linear-elastic moduli of different layers. To incorporate in pavement design and analysis, seismic moduli of different layers have to be adjusted to represent moduli at strain and stress levels that are close to those applied by truck traffic. To do so, the nonlinear and viscoelastic behaviors of different layers should be accurately determined. In this paper the process of using seismic data and laboratory tests to determine design modulus values and an attempt to validate this process are presented. Also included is a validation of the results based on FWD measurements.

Backcalculation analysis is generally greatly affected by errors in the measured deflection data. An average of multiple deflection data sets corresponding to a standard load is normally used in static backcalculation in order to reduce effects of these errors. However, this procedure can not be applied in case of time series data. A rather time consuming procedure is used, where backcalculation is performed using each deflection data set and then an average of the backcalculated pavement layer properties is determined. This paper proposes a new method where multiple sets of time series data can be used simultaneously in dynamic backcalculation to determine an average result. Computation time is similar to the case of one data set. Domain of analysis and the number of nodes are also examined.

This paper presents a sensitivity study on mechanistic responses of asphalt mixtures measured from two Superpave Shear Tester (SST) tests: the frequency sweep at constant height (FSCH) and repeated shear at constant height (RSCH) tests. Three special case studies were included in the analysis. A new critical complex shear modulus, G*_crit, derived from the FSCH test data, was introduced in this paper. Results indicated that using a single complex shear modulus value at one test frequency from the FSCH test could provide inconsistent ranking for mixtures with different temperature sensitivity. However, the calculated G*_crit stiffness values were found fairly sensitive to different mixture types and binder types considered. The critical complex shear modulus, G*_crit, is suggested to be used in rutting performance analysis.

Geogrids are used in flexible pavement construction to reinforce the aggregate base course, usually to stabilize the aggregate over soft subgrade soils. Many researchers, using various large-scale tests, have studied the benefits of base reinforcement geogrids. The wide range of reported findings is likely due to the differences between test procedures and the relatively high cost and extended time required to run the tests, discouraging the study of the various parameters involved. Thus, a relevant, standardized smaller-scale test to quantify base reinforcement is needed. One property—confinement of the base aggregate—is generally recognized to be of primary importance in achieving base reinforcement. A small-scale test has recently been developed that is able to quantify the effects of confinement offered by a geogrid, using out-of-plane loading to create multiaxial stress conditions relevant to base reinforcement. This paper reviews the development of the confinement test, comments on the results as compared to large-scale performance tests, and suggests how the results of confinement testing may be incorporated into design procedures.

The City of Twin Falls, Idaho constructed a geogrid-reinforced pavement section at the intersection of Washington Street and Filer Avenue in 2001. The Idaho Transportation Department (ITD) performed falling weight deflectometer (FWD) tests on this section of roadway after it was placed into service. The FWD data were analyzed to evaluate the benefits of the geogrid reinforcement. This paper describes the case history, analysis of the FWD data, and conclusions and recommendations regarding the use of geogrid reinforcement in this application. The results of the analysis were method dependent. Analysis of the FWD data using one method showed no benefit for the geogrid reinforcement, while a second analysis method concluded that the base course thickness could be reduced by about 20 percent. The most important observation is that a control section is absolutely critical to evaluating the benefit of geogrid reinforcement.

In 2000, the South Dakota Department of Transportation sponsored a research study to evaluate the impact of off-road vehicles on flexible pavements. This project included extensive field testing in which the pavement response was measured and theoretical modeling under a variety of loading and environmental conditions. The overall loaded areas under bulky off-road vehicle tires are much wider and the presence of tire lugs makes the contact stress distribution quite complex. The paper addresses both the development of appropriate contact stress distribution for off-road vehicle tires and comparison of computed and measured pavement responses. The extent of good comparison between the computed and measured pavement response values under a variety of loading and pavement structural and material conditions, support the applicability of the procedures adopted in the paper to evaluate the vehicle-pavement interaction stresses resulting from off-road vehicle loading.

This paper discusses the applications of DCP in the quality control of compaction of fill in several areas including select backfill, granular base layer, and backfill around utilities. Historically, the compaction levels of pavement subgrade and base layers have been determined by means of in-place density testing. Some testing has been recently performed on cohesive and select backfill material to determine whether there is a reasonable correlation between the DCPI and in-place compaction density. Most reported results of DCP testing have indicated that due to the high variability in DCP results, a correlation could not be applied. The DCP can, however, be effectively used in quality control of granular base layer compaction as well as during backfill compaction of pavement drain trenches. In addition, recent studies indicate that DCP blow count profiles provide a reasonable basis for comparison between compaction equipment, compaction levels, and materials for backfill and embedment materials in the installation of all underground utility structures, including the thermoplastic pipe used in gravity flow applications. A synthesis of current practices and results, and areas of possible future trends are presented.

Class F fly ash cannot be used alone in soil stabilization applications as it is not self-cementing. An activator such as Portland cement or lime must be added to produce cementitious products often called pozzolan stabilized mixtures. The developed mixture must possess adequate strength and durability, should be easily compacted, and most importantly should be economical and environmentally friendly. Roadways have a high potential for large volume use of the fly ash stabilized soils. The main objective of this study is to investigate the beneficial reuse of Class F fly ash amended soil-cement or soil-lime as base layers in highways. A battery of tests was conducted on soil-fly ash mixtures prepared with cement and lime as activators. Unconfined compression, California bearing ratio, and resilient modulus tests were conducted. Results of the study show that the strength of a mixture is highly dependent on the curing period, the compactive energy, cement content, and water content at compaction. Lime treatment does not provide sufficient strength for designing the mixtures as highway bases. A power function in terms of bulk stress used for granular soils can model the resilient moduli.

Fully drainable pavements are more commonly utilized as a solution to premature pavement distress. With these pavements, drainage is achieved by a coarse graded aggregate layer with little or no fines. The gradation of various soil and aggregate layers comprising a pavement must be such that intermixing of materials, and the resulting loss in performance, is minimized. A second solution is to utilize a geotextile separation layer at critical interfaces to prevent contamination from intermixing of adjoining materials. This solution permits a broader range of materials meeting strength and drainage requirements that can be used in a pavement. A review of the literature suggests that geotextiles are effective in performing the separation function in pavements. The primary design considerations for such geotextiles are construction survivability and soil retention. Geotextile construction damage decreases exponentially with an increase in mass per unit area. Geotextile apparent opening size is related by a factor of 1/2 to 1 with d₈₅ size of the soil being retained. The benefit of use of geotextile for any specific project depends on the availability and cost of soils and aggregates meeting filter and separation specifications.

The Long Term Pavement Performance (LTPP) Specific Pavement Study Experiment 2 (SPS-2), Strategic Study of Structural Factors for Jointed Plain Concrete Pavements (JPCP), is one of the key experiments of the LTPP program. The main objective of this experiment is to determine the relative influence and long-term effectiveness of JPCP design features (including slab thickness, PCC flexural strength, base type and drainage, and slab width) and site conditions on performance. It is expected that the successful completion of the SPS-2 experiment will lead to improvements in design procedures and standards for construction of jointed plain concrete pavements. These improvements will contribute to achieving the overall goal of the LTPP program—increased pavement life and better utilization of resources. This paper presents the key findings from a recently completed FHWA study that was the first-time comprehensive review and evaluation of the SPS-2 experiment. The results presented herein will be useful to both pavement researchers and practitioners for improving pavement design and management decisions, and for calibration and validation of mechanistic-empirical design models including the 2002 Design Guide models.

Several reconstructed Portland Cement Concrete (PCC) pavement projects in Iowa were recently studied to evaluate the influence of subgrade/subbase non-uniformity on pavement performance. Crack surveys and field tests to evaluate the subgrade/subbase were conducted. Dynamic cone penetrometer, nuclear density gauge, GeoGauge vibration, and Clegg Impact Hammer tests were performed in a grid pattern (2.5 m x 2.5 m over an area of about 7.5 m wide by 30 m long) to develop a database of the subgrade/subbase engineering property values. Results of stiffness, moisture and density, strength, and soil classification were used to produce plots indicating spatial variability of a given property. Natural subgrade soils, fly ash stabilized subgrade, reclaimed hydrated fly ash subbase, and aggregate subbase were studied. The influence of spatial variability of subgrade/subbase was evaluated by modeling elastic properties of the pavement and subgrade using the ISLAB2000 finite element analysis program. Results show that non-uniform subgrade/subbase stiffness increases localized deflections and causes stress concentrations in the pavement, which lead to fatigue cracking and other types of pavement distresses.

A comprehensive instrumentation system was installed at four sites across the state of Tennessee to monitor seasonal variations in the environmental factors affecting flexible pavement response. This paper presents some selected findings obtained from over five years of continuous data collection. The data included temperature and water content of the various pavement layers, and weather information. Falling weight deflectometer (FWD) tests were used to observe the pavement response during different seasons. The measured seasonal variations in subgrade and base water content were observed to be small. Consistent with these observations, the seasonal variations in FWD back calculated subgrade modulus were small, suggesting that these effects may not be important in the design of pavements in moderate climates. Since the pavement systems were new construction, little pavement distress was observed over the study period. However, as the pavements age, water infiltration may increase leading to greater water content changes in the unbound materials.

Rutting, the accumulation of permanent vertical deformation in a pavement structure, is one of the two major distress models used in the design of flexible pavements. Therefore the accurate determination of subgrade permanent deformation is a key consideration when using Mechanistic-Empirical methods for the design of flexible pavements. The power model proposed by Monismith et. al., to predict permanent strain of soils subjected to repeated loading, ε_p = AN^b, has been widely used as a predictor for the accumulation of permanent strain in pavements. Unfortunately, the parameters A and b must be experimentally determined by conducting relatively complicated and expensive repeated-load triaxial testing. This study attempts to relate the parameters A and b in Monismith's power model to soil properties that are more easily measured. An extensive set of repeated-load triaxial test data for eight typical Arkansas subgrade soils was used to get a range of A and b parameters for various test conditions and soil types. Using this data, the parameters of the power model were related to soil properties, which are normally measured for soil classification and quality control testing. Multi-variable regression analyses were conducted using a backward elimination technique to determine which soil properties had the most affect on A and b. Regression showed strong log-linearity between A and Stress Ratio and acceptable log-linearity between b and stress ratio. Further backward elimination regression also indicated strong relationships between certain simple soil properties and a new set of regression parameters that describe the relationship between parameters A, b, and Stress Ratio. By coupling all of the regression analyses a global equation was generated to predict the permanent strain of subgrade soils under varying stress conditions using those simple soil properties that are routinely measured for soil classification and quality control purposes.

The primary objective of this study is to develop a prototype database and geographic information system (GIS) structure for "network level" pavement management. The concepts of "sampling" and "uniform section" are proposed for domestic pavement network database structure and collection procedures based on the considerations of specific, measurable, achievable, relevant, and timely principles. Relational database structure of a commercial software package is adopted in this study. Many tables of pavement inventory, rehabilitation, traffic, and survey data are recorded using their original data collection formats for the ease of recording and updating. A systematic approach using various sorting and matching techniques is developed to overcome the current deficiencies of such relational databases based on the principle of "dynamic segmentation." Summarized uniform section databases are generated for different survey years automatically. Consequently, a prototype pavement "NETwork Dynamic Segmentation Database (NETDSD)" structure is developed using Microsoft Visual Basic and Access software packages with many user-friendly interfaces for recording, updating, summarizing, query and reporting purposes. A concise GIS presentation feature is also added to the program. This prototype program can be used as the core for future development and integration of our domestic network pavement databases and network optimization analysis.

Infrastructure development in the Rocky Mountain Front Range piedmont near Denver, Colorado is marked by unique hazards arising from underlying beds of steeply dipping, expansive bedrock. Efforts to reduce the occurrence of damaging differential movements among adjacent strata with dissimilar swelling characteristics often include overexcavation, remolding, and recompaction of the on-site materials. This paper examines the geotechnical engineering behavior of two end member materials obtained from adjacent shale strata at a steeply dipping site where overexcavation prior to construction is warranted. The series includes index (Atterberg limits), compaction, suction, and volume change (shrinkage) testing for each end member material as well as mass controlled mixtures of the end members. Linear relationships are noted between the relative mass fraction of the end members and the engineering behavior of the mixtures, thus allowing the swelling potential, compaction characteristics, and volume change characteristics of remolded fill at the site to be predicted from characteristics of the end member soils comprising it.

Expansive soils exhibit large volume changes due to moisture content fluctuations from seasonal changes. These volume changes cause extensive damages to geotechnical infrastructure. Several methods are available in the literature using different test methods and loading conditions to characterize expansive soils. The selection of an appropriate characterization method is always a challenge to the practicing engineer. A few case studies are presented to explain the need for better characterization of highway projects on expansive soils. This is followed by the descriptions on different characterization methods utilizing swell strain and swell pressures for estimating the severity nature of expansive soils. Both tables and correlations for characterization of expansive soils using swell strains and swell pressures are presented and discussed. The details presented in this paper are useful to provide reliable characterization for expansive soils and offer assistance to practicing engineers towards better design and selection of subgrade foundations and stabilization methods.

This study compares alternative approaches for differentiating and characterizing the swelling potential of steeply dipping strata in the Pierre Shale along the Colorado Front Range Urban Corridor. The hazard associated with this geologic setting is commonly referred to as heaving bedrock because adjacent strata expand to different degrees and may cause damaging differential deformation to residential and light commercial structures. This study is part of a larger investigation aimed at determining the feasibility of using reflectance spectroscopy, a remote sensing technology, to identify and characterize the swelling potential of expansive soils and bedrock. A trench in the Upper Pierre Shale was logged and 252 samples were taken horizontally with thin-walled brass tubes. Grain size, Atterberg Limits, filter paper suction, and clod tests provided, for each of the samples, the swell potential indices and rankings according to schemes proposed by Seed, Chen, and MeKeen. Swell-consolidation tests provided percent swell and swell pressure indices under in-situ surcharge pressures. All the indices are consistent in that they suggest the trench wall can be differentiated into two zones of steeply dipping strata overlain by a horizontal and shallow overburden soil. However, the schemes differ in that McKeen's indices vary over a significantly broader range of categories compared with the Seed and Chen indices. McKeen's indices and also the swell-consolidation indices have two advantages compared with Seed's and Chen's indices. They are obtained on relatively undisturbed materials and they are properties involved in quantitative heave prediction methods. These advantages suggest that McKeen's scheme is providing the most sensitive and useful basis for differentiating semi-quantitative categories of swelling potential at this site.

Stabilization of soils is an effective method for improving soil properties and pavement system performance. Cement kiln dust (CKD) represents an alternative to the traditional stabilization agents of lime, cement, and Class C fly ash. As with the other additives, cement kiln dust can be expected to vary in effectiveness depending on the soil type. A total of eight different soils with classifications of CH, CL, ML, SM, and SP were subjected to a series of durability tests, including freeze-thaw, wet-dry, and leach testing, to evaluate the relative performance of CKD as a stabilization agent. Results were compared with previous findings for the same soils stabilized with lime, cement, and fly ash. Atterberg limits and strength tests were conducted before and after selected durability tests. Relative values of soil stiffness were also tracked over a 28-day curing period using the soil stiffness gauge to evaluate ongoing reactions. The results provide guidance on which soil types can be expected to have significant improvements in performance with the addition of CKD.

Equilibrium moisture beneath highway pavements is critical to pavement design because moisture directly affects the strength and stiffness of pavement systems. Moisture is related to soil suction by means of the soil-water characteristic curve (SWCC). Previous research has indicated a correlation of suction with Thornthwaite Moisture Index (TMI) and soil type; however, these suction correlations exhibited large variability. Under an NCHRP project sponsored by the Federal Highway Administration, soil samples were collected from beneath thirty pavement sections throughout the United States: two from the WesTrack test facility, one from the MnRoad Project, and twenty-seven from the Long Term Pavement Performance sites. SWCCs and index properties were measured on collected samples at Arizona State University. The in-situ degree of saturation was obtained from soil index properties, dry unit weight, and moisture content, and the corresponding in-situ soil suction was obtained from SWCCs. Based on the field and laboratory data, an algorithm was developed to predict suction under the pavement using TMI, percent passing 200 (P₂₀₀), and Plasticity Index. The suction prediction models, named the TMI-P₂₀₀ model and the TMI-P₂₀₀/wPI model, showed good results with variability within acceptable limits.

A practical and direct method is explored for predicting volumetric strains due to moisture changes in highly plastic, expansive soils. Seasonal, differential movements from swelling and shrinking of expansive soils are a common cause of distress in highway pavements and light foundations in Texas and elsewhere. The problem of expansive soils has been studied by a number of researchers, but most published methods for predicting ground surface movements suffer from a reliance on limited empirical data, a need to run expensive and time consuming tests, and/or a lack of verification for highly plastic, natural soils. The proposed approach relies on test data acquired with conventional, commonly available test equipment, and predicts volume changes due to variations in water content at different total stress levels. Data on the shrink and swell behavior of a soil are obtained in a conventional consolidation test apparatus and are used to define a response surface relating one-dimensional strains to water content and total stress. The proposed method is demonstrated for Taylor Clay, a highly expansive soil commonly found in central Texas.

Dynamic pile testing and related data analysis methods are routinely used to measure soil resistance effects, estimate static pile load bearing capacity, and predict pile load-movement relationship. Analysis results represent conditions at the time of testing. For piles driven into soils with beneficial time-dependent characteristics, the capacity increases with time following initial driving due to favorable geotechnical effects. In practice, construction scheduling constraints often restrict the evaluation of "long-term" pile capacity and limit the verification testing to a short period following initial driving. This paper presents a method for predicting future pile load-movement relationship based on end of driving and short-term restrike dynamic testing results. A case study is presented where field dynamic tests were performed with a Pile Driving Analyzer® (PDA) and CAPWAP® computer analysis during initial driving and restrike eleven days later. The CAPWAP method was also used to predict the pile load-movement graph expected at seventeen days after end of initial driving for comparison with results from a full-scale conventional static loading test to be independently performed at that time. Good correlation was obtained between the dynamically predicted and full-scale static load test results based on the proposed method.

This paper describes the calibration of the Strain Wedge Model (SWM) response using the Treasure Island test measured data. The SWM, initially developed to assess the relationship between one-dimensional beam on elastic foundation (BEF) or so called "p-y" curve behavior and three dimensional soil pile interaction, has been extended to include laterally loaded piles/shafts in liquefiable soil. Because the SWM relies on the undrained stress-strain characterization of the soil as occurs in the triaxial test, it is capable of treating one or more layers of soils that experience limited or full liquefaction. This paper provides a methodology to assess the post-liquefaction response of an isolated pile/shaft in sand under an applied pile/shaft head load/moment combination assuming undrained conditions in the sand. The degradation in soil strength due to the free-field excess porewater (u_xs,ff), generated by the earthquake that results in developing or full liquefaction, is considered along with the near-field excess porewater pressure (u_{xs, nf}) generated by lateral loading from the superstructure. The tests include lateral load testing of 1- and 3-foot diameter piles/shafts at Treasure Island in San Francisco Bay Area in as-is and blast induced liquefied conditions.

This paper summarizes current methodology used for design of bridge foundations in Alaska. These bridges may cross rivers or other roads or railroads (grade separations). Piers and abutments may be supported on spread foundations or piles. This choice typically depends on subsurface conditions. However, piers in rivers or active river floodplains are often supported on pile foundations because of scour potential which would possibly undermine spread foundations. Applicable criteria for design of highway bridge foundations generally follow the 1998 AASHTO LRFD (Load and Resistance Factor Design) Bridge Design Specifications with latest updates. Some of the unique characteristics of bridge foundation design in Alaska are highlighted in this paper.

The marine piers of the new Benicia-Martinez Bridge are supported on 8 or 9 Cast-in-Drilled-Hole (CIDH) concrete piles with 2.5 m diameter permanent steel casings and 2.2 m diameter rock sockets to a depth of approximately 75 m. A Menck MHU-500 hammer was used to drive the casings up to 15 m into bedrock. The noise generated in the surrounding water unexpectedly killed fish. To resolve the environmental problem an affordable bubble curtain system was developed to reduce the sound wave energy by as much as 90 percent. Although pile driving monitoring did not detect any overstressing at refusal, some of the steel casings were found to be damaged. The damaged portions of the casings were removed and rock socket lengths were revised accordingly. Major caving occurred at Pier 8 during drilling of the rock sockets. Consolidation grouting was applied in an attempt to improve rock stability and to dimmish caving potential. However, subsequent continuous coring around the caved shaft could not confirm the effectiveness of grouting. The rotator drilling method was selected to construct the rock sockets. A pile load test (Osterberg Method) was performed to confirm the geotechnical pile capacities of the rotator-drilled shafts.

The TREX project is a $1.6B Design/Build underway in Denver, Colorado. The 17 mile long project is a combination of highway improvements to I-25 and I-225 and a new Light Rail Transit (LRT) line within the highway rights-of-way. The Contract required full-scale load tests on three drilled shafts. These were performed using the Osterberg Cell (O-Cell) method. The end-bearing and side shear measured in competent bedrock were well above design parameters determined using traditional Denver Area design methods. However, the test shafts in weathered bedrock had less than acceptable factors of safety (FS). Using the O-Cell tests results and data obtained as part of a Colorado Department of Transportation (CDOT) research study, the traditional Denver Area drilled shaft design method was modified for the weathered bedrock to meet AASHTO factor of safety requirements. The modified method was used to design the project drilled shaft foundations.

Non-Destructive Evaluation (NDE) of drilled shafts constructed under slurry is essential to verify constructed pile integrity. The function, application, and limitations of non-destructive testing of drilled shafts and the mitigation of detected anomalies will be highlighted by three illustrative case studies from California highway bridge projects. Special attention will be directed to the use of Gamma-Gamma Logging (GGL) for evaluation of shafts constructed under wet conditions. Gamma-Gamma Logging will also be compared to Crosshole Sonic Logging (CSL), with the relative merits and limitations of both GGL and CSL methods.

Load-deflection response of laterally loaded piles is often obtained via in-situ lateral pile load tests. Problems with such tests are the difficulties that occur during data interpretation. In an effort to develop an efficient method for analyzing deformation data of lateral loaded piles, an analytical model is proposed based on energy conservation of the pile soil system. The proposed analytical model not only provides a direct solution to the pile deflection function, but also has less need of complicated subsurface soil properties. In this paper, the authors present the theory and analytical model development of the proposed method. One real case is used to verify the feasibility of the developed methodology as well as to make comparison to other methods.

A case history involving the design and construction of the pier foundations for a fixed high level bridge over Nacote creek is presented. The bridge is supported on four piers with each pier being supported on four pre-stressed open-end concrete cylindrical piles of 1.37 m diameter and 165 mm wall thickness. Design concepts for cylindrical piles are outlined, with emphasis on modifications applied to Nordlund method to suit large diameter open-end driven piles. Static load test results performed on one cylindrical pile are presented. The adequacy of the design method is evaluated based on the static load test, as well as the PDA and CAPWAP data. The paper also discusses the installation sequence of the cylindrical piles. Finally, recommendations regarding design, construction, and dynamic testing of cylindrical piles are presented.

The new Carquinez Bridge is a suspension bridge with spans of 147 m, 728 m, and 181 m. It consists of the south anchorage, a transition pier, two towers (South and North towers), and the north anchorage. This paper describes the rock conditions and available rock strength data beneath each tower foundation and the design considerations and procedure used for estimating the axial capacity of the rock sockets for the piles for the tower foundations. The towers are each founded on two footings, which are each supported by six vertical, 3-m-diameter steel shells infilled with reinforced concrete, followed by 2.7-m-diameter drilled shafts in rock (i.e., cast-in-drilled hole, or CIDH, piles). The total length of the CIDH pile at the South Tower is approximately 89 m, with about 43 m of drilled shaft in rock. The total length of the CIDH pile at the North Tower ranges from 49 to 64 m, with about 16 to 26 m of drilled shaft in rock. The design parameters used for the South Tower piles were later confirmed by a pile load test. Additional field investigations during construction revealed significant variations in rock conditions at the North Tower, resulting in the redesign of the length of the piles. Major construction challenges encountered during construction of the South Tower piles are described, and the revised construction procedure (i.e., under-reaming) used by the constructor to mitigate caving is presented.

The details of a lateral load test performed on a 1.8 m (6 ft) and an 2.4 m (8 ft) diameter monopile fabricated of high-strength glass fiber reinforced composite materials are presented within the paper. After installation of the piles by jetting and vibrating, the piles were laterally loaded by pulling the two piles together using a uniquely designed jacking system. The lateral deformations along the length of the piles were measured by using an inclinometer probe placed in casing that was fixed to the inside of the monopiles. The results from these measurements are presented and compared to lateral pile calculations performed prior to the load test. The load test results indicate that the pile deflections were greater than those predicted by the lateral pile calculations. A discussion is presented that provides possible reasons for the significant difference between the measured and calculated results.

This paper will illustrate the use of non-destructive testing (NDT) as a means to verify the quality of the construction of drilled shafts. A review of the recent advances and direction of the Federal Highway Administration (FHWA) on this issue will be provided. The NDT methods emphasized will be Gamma-Gamma Logging and Crosshole Sonic Logging and the use of the two in concert will be examined. The mitigation process for defects identified within shafts will also be addressed. The Trabuco Creek Bridge Project will also be utilized as a case study to illustrate the concepts forwarded in this paper.

Drilled shafts are used in many civil engineering projects including bridges, retaining walls, offshore structures, and tanks. Advantages of drilled shafts include the fact that the excavation can be readily inspected and the competency of the bearing material can be verified. The Arizona Department of Transportation (ADOT) makes extensive use of relatively large drilled shafts for foundation support of transportation structures. Because of this interest in drilled shaft behavior, ADOT has sponsored research on drilled shaft performance and the field load tests reported in this paper. Lateral load tests were performed on four 1.07 m (42 in) diameter drilled shafts at the 101 Freeway and Warner Road in Tempe, Arizona. Loads and deflections at the shaft top were measured and strain gages were used to ascertain the distribution of moments within the drilled shafts. The strain gages were used to develop p-y curves for the cemented soils at the text site.

Near Greenville, Mississippi, sixty-seven piers along the approach structures for U.S. 82 over the Mississippi River are to be founded on groups of drilled shafts, 820 shafts total. Mississippi Department of Transportation (MDOT) chose to perform several Osterberg Cell load tests in advance of construction to refine shaft design lengths. MDOT contracted with HNTB Corporation to design the load test program, analyze the load test data, and provide axial capacity curves. Eight full-scale load tests were run in the fall of 2002. Results supported use of effective stress design methods for predicting side shear in the cohesionless and cohesive alluvial deposits tested. Use of the K_otan(δ) approach for estimating β in cohesionless deposits was also validated. Measured tip resistances in sands with gravel exceeded blowcount-based estimates. This paper summarizes design and construction of the load test program, presents side shear and end bearing test data, and describes foundation design methods adopted as a result of the program.

Lateral deformations caused by the installation of 0.76 m to 1.5 m diameter, caissons were measured by inclinometers placed at the excavation for the Lurie Research Center in Chicago, IL. The bells of the caissons were founded at an average elevation of –23.8 m Chicago City Datum (CCD). Subsurface conditions at the site and construction techniques used to install the caissons are described. Eight inclinometers were placed around the perimeter of the site and one inclinometer was placed in an ad hoc test section consisting of two caissons located in the interior of the site. The ad hoc test section and production caisson inclinometer responses are compared. The times needed to construct the production caissons around the exterior of the site and the test section caissons were very similar so that the time-dependent responses of the clays squeezing into the caisson did not cause differences in the observed responses. Larger ground movements were observed adjacent to the production caissons located near the perimeter of the temporary wall than adjacent to the two caissons located at the test section in the interior of the site. The performance data show a correlation between lateral movements caused by installing caissons and the stability number. A finite element simulation models the stress differences between the production and test section caissons. An empirical means to estimate the movements associated with caisson construction is provided.

The Richmond-San Rafael Toll Bridge, spanning the northern end of the San Francisco Bay on Interstate Freeway 580, is undergoing extensive seismic retrofit, which will prevent it from collapsing during a major earthquake. To increase the axial foundation capacities in compression and tension, micropiles are installed in between the existing H-piles. The installation is carried out by placing a micropile template on top of the conical section of the bell foundation and coring 355 mm holes with grooved surface through the existing bell. Then a 324 mm diameter permanent steel casing is advanced through each of the cored and grooved holes. A 292 mm diameter rock socket is then drilled from the bottom of the permanent casing into bedrock. While the tip of permanent casing is defined, the length of rock socket varies depending upon rock quality, load demands, and other design constraints, including a designated minimum bedrock embedment length. Grout is tremied after the reinforcement of 210 mm diameter steel pipe is placed inside the casing and rock socket. Acceptance criteria for micropiles are based on specific tension load demand at each support location and the maximum allowable vertical movement under that load. Two tension load tests are performed at each pier location to confirm that the micropiles meet the acceptance criteria.

Piles with a variable perimeter over all or part of their length are generically called tapered piles. The benefit of using tapered piles when axial-compressive loads predominate, especially in `friction' situations involving coarse-grain soils, has been recognized in principle for a long time. However, this benefit does not appear to have been fully exploited in practice, especially in transportation applications. Several recent events have produced a rebirth of interest in tapered piles, at least in U.S. practice. One was the development and commercial introduction of a new type of proprietary tapered steel pipe pile called the Tapertube^TM. It was developed primarily to provide commercial competition to the long-established Monotube pile but it has also demonstrated that it is a structurally robust pile capable of withstanding the stresses of today's high-capacity design requirements. Of relevance to this conference is that Tapertube piles were essentially developed for, and eventually used extensively on, one of the larger transportation-related projects in the New York City metropolitan area in recent years, the major renovation and expansion work at the John F. Kennedy International Airport. This work included both terminal buildings and several kilometres of elevated light-rail structures as well as project-wide design for seismic loading. As a result, a comprehensive pile-load-test program was conducted to verify the performance of Tapertube piles under compressive, uplift and lateral loads.

Driven plate anchors can be used to hold in place large bridge caissons during floating construction. Their small size and simple method of installation make them a very cost effective alternative to other direct-embedment, gravity, and drag anchors. The geotechnical design of plate anchors involves the anchor geometry, embedment, drivability, and proof testing. This paper describes the experience gained with plate anchors used during construction of the new Tacoma Narrows Bridge. For this project, the anchors had to be driven in dense to very dense sands, and had to resist large forces from 7–9 knot currents.

Because steel and concrete piles can degrade in marine environments, composite piles employing fiber reinforced polymer to replace and/or protect steel and concrete are being considered for support of highway bridges. Although such alternative piles have relatively high initial costs, they may have reduced life-cycle costs resulting from reduced maintenance costs and longer service life. However, there are impediments to using composite piles, including a paucity of documented case histories and a lack of verified analysis and design procedures. This paper describes use of composite piles at the Route 40 bridge across the Nottoway River in Virginia. One bent of the bridge is entirely supported on composite piles formed of fiber reinforced polymer tubes filled with concrete and without any steel reinforcing. A test pile program was performed at the bridge site, in which a prestressed concrete pile and a composite pile were loaded laterally using a Statnamic device. Both test piles exhibited about the same lateral load versus deflection response up to a load of about 50 kN. Beyond this, the composite pile response was much less stiff than the prestressed concrete pile response. Calculations of lateral load versus deflection were made for both test piles using the p-y methodology. The same set of p-y parameter values provided reasonably good agreement between the calculated response and the results of the Statnamic tests. This indicates that standard methods of calculating the load-deflection response of concrete piles can be used for composite piles, at least for the type of composite pile employed at the Route 40 bridge.

This paper details the Value Engineering efforts to design and install micropiles as an alternative to the as-designed driven and pre-drilled H-piles situated over karst terrain. A total of 295, 178 mm (7-in) diameter micropiles with an axial compression capacity of 890 kN (200-kips) were installed for the bridge structures to replace 511 driven and pre-drilled H-piles with an axial compression capacity of 445 kN (100-kips). In karst areas where cutter and pinnacle formations must be penetrated, micropiles are readily advanced through these formations and socketed into competent bedrock. Innovative grout mix design and construction techniques minimize grout loss within cavernous material to develop a competent bond zone. Seven compression load tests were conducted to verify the design bond stress values. This paper also presents bond stress values from micropile load tests conducted on similar projects situated over karst in an effort to assess the current state of practice.

Deep mixing stabilization supports new embankments over deposits of soft organic silts and clays at the I-95/US Route 1 interchange reconstruction in Alexandria, Virginia. During design, an instrumented test embankment was constructed on dry mix columns to assess performance of this technology at the interchange site. Numerical modeling disclosed that the most significant material properties affecting stress concentrations in the soil above the columns are the strength and stiffness of the columns, while the shear modulus of the untreated clay is most important for lateral deformations at the end of construction. As the column strength and stiffness increase, the stress concentration ratio increases. As the soil shear modulus increases, the lateral deflections decrease. The values of stress concentration ratio from the calibrated numerical model are 4.2 and 2.1 for area replacement ratios of 6.4% and 17.9%, respectively.

The Minnesota Department of Transportation (Mn/DOT) embarked on their first use of Deep Mixing Methods (DMM) in the fall of 2002. The technology, while not new to the United States, was new to Mn/DOT and the implementation required a considerable amount of additional oversight and attention. The deep mixing (DM) work was to consist of approximately 60,000 m³ of treated ground as part of a $45M project involving three bridges, six approach ramps, roadway reconstruction and associated grading, paving, signing, and signals. Unusual to most Mn/DOT projects, geotechnical engineers were involved through both design and construction of the foundation work; involvement ranged from providing the original design concept and development of the plans, special provisions, and QA/QC (Quality Assurance/Quality Control) program, to the consideration of contractor value engineering (VE) proposals, assessment of sampling and coring of specimens, and assisting in the resolution of construction issues involving a problematic site strata with cobbles and boulders. Designing and preparing the necessary specifications and contract documents took more effort than originally predicted. In addition, despite careful attention to detail, there were two significant areas in the special provisions where confusion occurred: definition of pay items and the monitoring/instrumentation program.

Deep mixing is effectively used in excavations both in conjunction with and in substitution of traditional techniques, where it results in more economical and convenient solutions for the stability of the system and the prevention of seepage. Deep mixed walls constructed as part of a soldier pile and tie-backs system act also as temporary support, prevent seepage like a sheet pile wall, but require a lower amount of steel. The deep mixed treatment can also contribute to the stability of the wall system against deep-seated failures. Although deep mixing is currently used for excavation control in numerous projects, no standard procedure has been developed and the different applications have not been evaluated. As this technique emerges as a more economical and effective alternative to traditional excavation shoring, there is a need for guidelines describing proven procedures for evaluation of design, analysis and construction. This paper presents comparisons in the design of excavation support using deep mixing and other traditional techniques. Issues important for design, analysis, and construction of deep mixed excavation walls are also discussed.

The lime cement dry mix process and its applications to the construction of highway or railroad embankments immediately adjacent to existing highways or railroad lines is described. The construction of a 15m high embankment on medium to stiff Lake Bonneville soils as part of the widening and reconstruction of Interstate 15 in Salt Lake City, UT and the construction of 6m embankments on soft Young Bay Mud for the extension of the BART system to San Francisco, CA International Airport are the examples included here. The embankments for BART are within about 3m of the existing CalTrains system. Damage to the existing facilities was avoided. Advances in the lime cement dry mix process were developed and are described.

A Modified Dry Mixing (MDM) method has been developed. By an innovative modification to the existing dry mixing process and equipment, water can be injected into the soil during the installation process. By adjusting the water content of the soil, columns of significant strength can be produced even in various soils of very low water content, where the regular dry method normally could not be used. The MDM process also yields improvements in mixing efficiency resulting in more homogenous columns of high quality. During the development, a feasibility full-scale field test was performed showing promising results and improvements compared to the regular dry mixing method. This paper presents the possibilities of the MDM method and the field test results.

When embankments are constructed over soft foundations, stability often becomes one of the controlling factors in design. Deep mixing methods have been commonly used as an alternative to improve soft soil to enhance the stability. Bishop's modified method is a commonly adopted approach for analyzing slope stability including embankments over deep mixed (DM) foundations. Bishop's modified method assumed failure along a circular slip surface and the soils along this slip surface provide shear resistance. However, experimental and numerical studies have showed that deep mixed columns under a combination of vertical and horizontal forces could fail due to shearing or bending. The bending failure cannot be analyzed by Bishop's method. A finite difference method was used in this study to evaluate the factors influencing the stability of embankments over deep mixed foundations, which include strength, spacing, and size of DM columns, undrained shear strength and thickness of soft soil, quality and height of embankment fill, and traffic loading. Mohr-Coulomb failure criterion was used for embankment fill, foundation soil, and deep mixed columns. In addition, the tensile strength of deep mixed columns was assumed to be 10% of their undrained shear strength. A row of deep mixed columns was modeled as a wall in 2-D for simplicity of analysis. Deep mixed columns were embedded into a firm soil to create a possibility of bending failure. The numerical analysis indicated that the factors of safety of the embankments over DM foundations depend on these influence factors and the failure mode changes from deep-seated failure to slope failure within the embankment fill.

As a measure to reduce lateral deformation and settlement due to road embankment loading on the soft clay ground, the column type Deep Mixing method used at a low improvement ratio of around 10–20% (LiDM) has been found to have sufficient performance and to save total costs. The main features of this method can be summarized as follows: (1) Since the whole bottom surface of embankment is improved all over, shear deformation toward outside of embankment due to settlement at the center part can be reduced compared with the conventional type. (2) Since the volume of embankment can be saved due to sufficient reduction of settlement, LiDM is considered to be environment-friendly. (3) When the column diameter is small (60–80 cm), small sized installation equipment and a simple loading test for quality control can be used. A rational design procedure for the LiDM has been formulated based on the results of laboratory model test. This paper reports on a study of this design procedure's suitability, using some cases of numerical analysis and case study of the expressway widening project near Bangkok in Thailand. It further discusses the improvement mechanism of the floating type Low improvement ratio Deep Mixing method.

This paper develops a correlation of the unconfined compressive strength of treated peat-cement samples. The strength is directly evaluated from mechanically-mixed specimens and laboratory-scale auger columns. The results obtained show both the effect of the cement quantity and the effect of two specimen sizes on strength. Generally, the higher the quantity of cement added to the peat, the higher the strength gained. Furthermore, a comparison between results in this study show that the strength obtained from mechanically-mixed specimens is twice as large as that obtained from laboratory-scale auger columns. Therefore, the conclusion is that the parameters obtained from laboratory-scale auger columns can be closer to those measured at the field than those obtained from mechanically-mixed samples.

This paper details results of a preliminary investigation into the influence of different curing environments for accelerating the ageing of four cement-based grouts used to treat contaminated soils. The grouts consisted of a combination of cement, ash, lime and bentonite. The behaviour of both uncontaminated and contaminated materials was considered. The contaminants used comprised of compounds of five heavy metals (Pb, Cu, Cd, Ni and Zn) and paraffin oil. Samples were cured adopting exposure to elevated temperature and carbon dioxide (accelerated carbonation). Tests were conducted for strength, carbonated depth, leachate pH and x-ray diffraction after 28, 90 and 180 days of curing. The results suggested that the four grouts behaved differently under these different curing conditions, with the exposure to elevated temperature being the more consistent of the two environments.

Coode Island Silt (CIS) is one of the youngest formed sedimentary formations in the Melbourne geological region of the Yarra Delta. Because it is a highly compressible material, CIS imposes geotechnical constraints on the design and performance of infrastructure works. This paper investigates the effectiveness of using soil mixing technology via cement stabilisation of CIS by studying the improvement of the strength of the treated soils. Tests were carried out in two stages: 1) laboratory based stabilization of CIS and 2) small scale model mixing. The improvement in terms of strength was assessed using unconfined compressive strength (UCS) test. A small-scaled model mixing was set up to mimic the actual mixing scenario on sites. Although it may not be perfect, it gives an indication on the effectiveness of the cement slurry when combining with the silty clay.

Deep mixing (DM) technology involves the mixing of soils extending to large depths with cement, or lime, or other types of stabilizers for raising the strength of soft and compressible soils, reduction of settlements of roads, embankments, and enhancing the stability of excavation supports and slopes. Quality assurance (QA) of deep mixing methods used in the construction projects must be addressed to evaluate the effectiveness of DM treatment methods adapted in the field. If not addressed, columns with deficient strength and stiffness properties will induce damage to infrastructures built on them. Several in situ testing protocols for QA studies were developed as a part of a research study conducted for the National Deep Mixing Program. This protocol development was based on extensive literature reviews, documented case study information and surveys with practitioners associated with the in situ methods. This paper provides comprehensive details on three testing protocols of standard penetration test, cone penetration test and pressuremeter test. The protocols covered both step by step testing methodologies on soil columns, and interpretation methods for strength and stiffness properties. A case study example utilizing SPT protocol is presented to illustrate the steps in QA studies.

The phenomenon of swelling is one of the catalysts in the progressive deterioration of a tunnel section constructed between 1973 and 1975 in the Georgian Bay shale rock formation found in Mississauga, Canada. A 1.68 km 3 m diameter storm sewer tunnel was advanced using various techniques. Distress of the tunnel lining along the drill and blast section was observed as early as 1977. Convergence readings and inspection of the lining were carried out regularly between 1987 and 1991 at which time a 4 mm horizontal convergence of the tunnel was recorded. The tunnel section currently exhibits characteristic structural failure of the lining with tension cracks up to 20 mm in width at the spring lines. Rock cores extracted in 1977 and 2001 were tested for swelling potential. A general decrease in the swelling potential of the rock and a significant reduction in its strength and stiffness properties were observed over time. The results of the tests were used to estimate the current horizontal and vertical stresses on the tunnel lining in order to develop tunnel rehabilitation alternatives. This paper presents the results of the laboratory tests and monitoring data of the tunnel lining closure and discusses the strategies considered for rehabilitation of the tunnel.

Plagued by leakage problems since the time they were constructed, Toronto's underground network of subway tunnels and structures have undergone a major leak remediation program. The spring of 2004 marks the seventh year of a very successfully implemented solution grouting program. This project has been the largest on-going solution grouting project in North America for the last five years. The Toronto Transit Commission's water problems were brought under control with the use of a "back-wall" grouting technique that took into account the multiple phase, multiple stage grouting operations that were anticipated and required to successfully shut off the leakage problems. The water infiltration problems was causing accelerated aging of the rail and rail fastening systems, deterioration and malfunction of electrical systems and their components and decay of the structure itself as well as causing both service delays and concerns for passenger safety. All the work had to be performed during the nightly two-hour maintenance working window without impact to customer service. This paper hopes to provide some helpful insight on the key aspects of this specific sealing system engineered and designed to solve Toronto's subway tunnel and station leakage problems. This successful design continues to be the leak remediation solution of choice for this public transportation authority.

This paper outlines the progress of work on the Dublin Port Tunnel project together with describing the principal transportation engineering, geotechnical and environmental aspects relating to the design, construction and future operation of the tunnel, which is currently one of Europe's largest urban road tunnel construction projects at US $790 million. The Dublin Port Tunnel is situated in Ireland's capital City, Dublin and will provide an underground road link between the City's orbital motorway system in the suburbs, to the Port located in the City centre area. The primary purpose of the project is to remove heavy goods vehicle `through' traffic from the City centre and residential areas by providing a high quality access route to and from the Port.

State-of-the-art design and construction techniques resulted in a unique immersed concrete tunnel crossing in northwestern Greece in a region characterized by high seismicity and weak foundation soils. Ground improvement works to mitigate liquefaction potential included installation of marine and land stone columns along the entire tunnel width and length. The most important features of the project are presented with emphasis on site specific characteristics, design principles, and construction highlights.

Increasingly, large-scale structures are being constructed underground in order to maximize effective use of limited land area. Use of conventional cut & cover or TBM methods in such cases poses problems in terms of detrimental impact on above-ground transport, the securing of boundaries between public and private sectors, and the disposal of excavated soil and other environmental matters. A construction method that can efficiently resolve these problems is needed. The Multi-Micro Shield Tunneling (MMST) method, a non-open cut tunneling method for constructing underground structures with large cross-sections, was developed to resolve these problems. The world's first application of the MMST method was for the construction of the ventilation tunnels connecting the Trans-Kawasaki Expressway tunnel and the ventilating station within the Daishi Junction. Implemented as a test construction, the work was completed in 1999, and various data were collected. This paper describes the unique structural problems involved in constructing the tunnel structure for the main Trans-Kawasaki Expressway using the MMST method, compiled based on the knowledge gained from the test construction. It also covers the results of confirmation tests and the MMST design techniques reflecting the results of these tests.

The design and construction of a jacking shaft, ground improvement, and microtunneling in the ocean presented unique challenges due to the general lack of precedents. The need to construct a new 3.9-km long ocean outfall beneath coral reefs and environmentally sensitive ocean floor was successfully resolved by specifying over water shaft construction and underwater microtunneling along 800 m of the new outfall alignment. Geotechnical site characterization included over water drilling and sampling, and marine geophysical surveys. The selected microtunneling alignment avoided thick deposits (over 50 m) of very loose, liquefiable sands. Two approximately 400-m long microtunnel drives, one jacking shaft, and two under water retrieval pits were specified. The microtunneling jacking shaft, related jet grouting, and underwater retrieval pits were constructed in open ocean waters over 6 m deep, with the microtunneling shaft bottom at 12 m below sea level. The geotechnical and trenchless engineering design approach, overwater shaft construction and performance characteristics, and microtunneling performance in very loose sands to hard coral limestone will be discussed.

In 1989, about 9 m of an existing, 90 years old, 2.4 m diameter water tunnel collapsed due to a catastrophic landslide in the mid section of the 610 m high Hakalaoa Falls. The tunnel was part of a 35 km tunnel- ditch system, and only about 3 m to 8 m from the cliff face at the collapsed location. Diversion of water from Hakalaoa Fall triggered litigations. Design of the bypass tunnel faced the following challenges: (1) Lack of time and budget available for a thorough investigation. (2) Selecting a tunneling method that can effectively excavate a wide range of materials from very hard rocks to caving clinkers, and allow the excavated materials to be transported 2 miles up the small existing, meandering tunnel. (3) Designing a tunnel support system that can be transported and installed cost effectively in the remote tunnel excavation. In May 2001, an engineering geologic reconnaissance was performed, and with a combination of geo-mechanics rock mass quality evaluation and finite element analysis was used to evaluate tunnel alignment, anticipated tunneling conditions, and tunneling methods. Construction of the 76 m, 2134 mm, hand mined, liner plate supported by-pass tunnel started in November 2001, and was completed in Spring 2002.

Following the tragic events of September 11, 2001, the Port Authority of NY & NJ (PANYNJ) set in motion plans to re-establish commuter rail service to its former Port Authority Trans-Hudson (PATH) World Trade Center (WTC) Station, which plans involved constructing a new, temporary WTC Station, reconstruction of the flooded twin Hudson River tunnels and upgrading the Exchange Place Station to accommodate "terminal" rail services. This paper discusses relevant tunnel design and construction approaches and processes associated with the Exchange Place Improvements Project. This project represents the first use of road-header type excavation equipment and the first application of steel fiber reinforced shotcrete (SFRS) liner systems for ground support on a mass transit project within the New York City Metropolitan Region.

Comprehensive and realistic tunneling plans must strive for optimal decisions that minimize time and cost while addressing important factors such as geologic uncertainty and variability, uncertainty in tunneling productivity, and the contractor's risk sensitivity. This paper presents a computerized decision support system that incorporates all important tunneling risks. It consists of three interrelated models: the probabilistic geologic prediction model, the probabilistic tunnel cost estimating model, and the risk-sensitive dynamic decision model. The probabilistic geologic prediction model uses all available geologic information to characterize geologic uncertainty and variability along the tunnel profile in the probabilistic form of ground class transitions. The probabilistic tunnel cost estimating model evaluates tunneling time and cost performances for applying different excavation and support methods to different prevailing ground conditions by using Monte Carlo simulation to actual tunneling operations. Both models provide the main input for the risk-sensitive dynamic decision model, the core of the system, to determine the optimal excavation and support sequence and the corresponding risk-adjusted tunneling costs for the project as functions of available project information and the contractor's risk sensitivity. The application of the system to an actual highway tunneling project illustrates both the modeling power of the approach to quantify and incorporate risk, and its effectiveness for making optimal decisions as functions of the contractor's degree of risk sensitivity.

Assessment of TBM tunneling conditions and potential for damage in building and archaeological remains is of greatest benefit in resolving problems associated with the construction of the Athens Metro, Greece. In this predictive philosoply an overbreak risk assessment method was developed based on intuitive simplicity, theoretical background and past experience. The method evaluates ground conditions from boreholes and defines risk on the basis of hazard severity and likelihood of occurrence. As the method proved macroscopically efficient, research on the subject is ongoing with evaluation of monitoring data gathered during construction and back analyses using numerical techniques.

Groundwater control during cut-and-cover tunnel construction of a half-mile segment of the Central Artery I-93 Northbound Tunnel requiring excavation to more than 100 feet below ground surface resulted in temporary depression of the groundwater and settlements to adjacent structures, including two high-rise buildings. The reduction in groundwater levels outside the excavation limits generally had a greater effect on adjacent structures than any other construction activity, with the amount of settlement varying with distance from excavation, subsurface conditions and foundation type. Generally uniform settlements were recorded within the footprint of the high-rise building discussed herein, with maximum settlements reaching approximately ½ inch. This paper describes the dewatering along a portion of the Central Artery Corridor, measures used to minimize groundwater lowering outside the excavation limits, and effect on three adjacent structures. Comparisons between predicted versus measured performance are presented, including time history plots of piezometric levels and settlement at each building.

The Second Avenue Subway is a major transportation project in the New York region, which will significantly expand MTA's subway system. Second Avenue Subway is currently the largest underground infrastructure project in the world. This project will generate enormous benefits for the residents and businesses of New York City and the New York region. The paper chronicles the history of the Second Avenue Subway Project from its original inception in 1929 to the current Preliminary Engineering stage of design. The paper discusses the project as a whole and then focuses on some of the unique challenges facing client and designer when dealing with underground construction in New York City.

Construction of transportation infrastructure often involves resolving conflicts between intersecting transportation modes. Trenchless technologies allow for construction of buried structures with minimal disruption to surface transportation systems. This paper describes the use of horizontal directional drilling (HDD) to construct a 24-inch diameter natural gas transmission pipeline beneath an interstate highway and regional aqueduct. Prior to construction a hydraulic fracturing analysis was performed to evaluate the potential impact of pipeline construction on existing surface structures. During construction, quality assurance observation and testing was performed to evaluate compliance with permit conditions and good drilling practices. After construction was completed, a mass balance calculation was performed to estimate the amount of solids in the slurry remaining in the annulus around the installed pipeline. Results of the mass balance calculation suggested that the slurry remaining in the borehole was substantially heavier than the slurry that flowed out of the borehole during construction.

Construction of subsurface railway projects within the urban environment, whether for mass transit, commuter or freight rail or light rail, face unique challenges in their design and construction. There are many retaining systems available to the geotechnical engineer, however they do not all satisfy the constraints of the urban environment. The selection of an appropriate retaining system is driven by these unique constraints. This paper describes the retaining wall types available and some classification systems that are used to categorize them, and discusses the unique constraints of the urban environment and the ability of the available retaining systems to address these constraints.

Subsurface conditions at the site of a large box culvert constructed beneath a deteriorating bridge consisted of highly compressible alluvial clay. Concerned with settlements estimated up to 50 cm, engineers considered completely removing and rebuilding the bridge structure. With estimated settlements still exceeding 10 cm, rammed aggregate piers were selected for installation beneath the box culvert to control differential settlement and prevent downdrag on the existing bridge pier foundations. Despite construction challenges including high water table, very soft soil conditions, and low clearance for machinery beneath the bridge structure, it was determined that the benefits of the box culvert and embankment (i.e. ease of future roadway expansion and continual service of the highway throughout construction) outweighed the cost of replacing the bridge structure. Approximately 250 rammed aggregate piers were installed in a grid pattern with lengths ranging from 2.3 m to 6.7 m depending on embankment fill heights. Performance was monitored with settlement plates and compared to predictions.

Maintaining mainline active rail track in good condition is critical for continued productive and safe use. Thus several railway track sites along the banks of major rivers with histories of ground movement are being studied. The paper presents results of the geophysical survey of one site, 1,200 feet in length, located 100 feet from the Ohio river. The focus is on evaluating track bulk moisture characteristics in track substructure. A geophysical survey consisting of ground penetrating radar, seismic, gravity, very low frequency and resistivity measurements were conducted. A high accuracy differential global positioning system surveying technique was used to determine elevation profile and vertical settlement of the track.

Taiwan High Speed Rail (THSR) is the most important traffic infrastructure for the next decade in Taiwan. The tracking system is extremely vulnerable to the damage of differential settlement. However, at the transition areas such as bridge approach, differential settlement will likely occur due to different material stiffness. Use of cement-treated technical backfill instead of conventional granular backfill has shown promising hydrocollapse reduction and strength increase. However, the improvement will be limited due to the limited moisture within the material for cement hydration. Based on the research, technical backfill treated with 3.2 to 7.5% cement can minimize the hydrocollapse. For best service results, technical backfill still requires to be compacted to 95 % of the modified Proctor density with moisture content preferably of about OMC+2 %. The results of the study provide helpful suggestions to control the settlement potential for the THSR embankment.

The Los Angeles to Pasadena Metro Gold Line Rail Transit Project provided many challenges with a variety of different geotechnical conditions along its alignment. The conditions include areas of deep existing fill soils at Union Station and the Yard and Shops area. Evaluations were made as to whether the existing fill could be used for support or whether the fill should be improved. The project includes a major crossing over the Los Angeles River where there were different soil and rock conditions at the two major pier locations. The project crosses a known active landslide area which required evaluation of stability and adequacy of mitigation measures. The project includes two areas of below grade construction in materials difficult to excavate; one of the areas was adjacent to an historic commercial district with many older unreinforced masonry buildings sensitive to ground movement. The project also had a crossing over the trace of an active earthquake fault.

An instrumentation program was undertaken to evaluate the relative damage to railway track from various classes of traffic: loaded freight, empty freight, passenger, and high-speed intercity. As part of this investigation, the roadbed deflection was targeted for measurement since the roadbed deflection is the main characteristic differentiating track performance for these classes of traffic. The project involved installation and calibration of the sensors, measuring the track response under a test freight train, measuring the deflection from passing traffic, and analyzing the data to determine the deflection distribution in the track structure and the damage induced by the different classes of traffic. Based on the analysis, a traffic based track condition deterioration model was developed and applied to the test section. The results of the analysis were confirmed with a program to monitor the overall track settlement and deformation of the roadbed. The monitoring program indicated that the predictive model estimated the track deterioration rate relatively accurately and could be applied to other sites with the addition of site specific traffic volume, maintenance records, and local site geology or field tests to estimate roadbed and subgrade characteristics. This paper describes the test, summarizes the results and analysis, and provides an example of the application of the results.

Colorado impact rail designs follow the AASHTO Standard Specification for bridge deck overhangs, where it uses a 44.5 kN equivalent service load. In the AASHTO LRFD 2000 Code, the impact load was changed to an ultimate static load of TL1 (60 kN) to TL6 (780 kN) without providing design details and the Colorado Department of Transportation (CDOT) began its research to establish design details. Colorado railings in bridge approach usually sit on mechanically stabilized earth (MSE) walls and the impact load transfer from rails to walls becomes critical to rail stability and MSE wall design. Nonlinear quasi-static and impact load finite element analyses were performed to evaluate the stability and impact transfer efficiency of Colorado Type 7 and Type 10 rails with concrete and steel barriers, respectively under TL4 (240 kN) and TL5a (516 kN) impact loads. The finite element modeling demonstrated that the current design was effective at resisting impact loads if the rails were long and continuous. However, the modeling indicated that the system might not perform adequately if the impact occurred close to the end of the rail. Further research is needed to simulate true dynamic loading and to validate the results with actual crash tests.

The Channel Tunnel Rail Link (CTRL) is a new 109 km long high speed railway, currently under construction, which will run between Central London and the English portal of the Channel Tunnel, thus linking the UK to the rest of the European high speed rail network. The first 75 km long length opened to traffic in October 2003, and the entire route will open in 2006. The route runs through almost the entire geological strata of South East England. It also runs through several areas of derelict land, where it is envisaged that the new link will encourage regeneration. The CTRL earthworks involved the engineering of over 30 million m³ of excavation and fill. The paper describes the philosophies adopted for their design and construction. An important requirement of the parliamentary legislation which gave powers to construct the railway was a requirement to minimise waste and encourage sustainable practice in the design and construction of the link, and the ways that these were achieved are discussed in the paper. The trackbed design is briefly discussed.

The results of a lateral spread study are presented in this paper for a bridge-widening project in Southern California. The existing bridge spans a creek underlain by loose to medium dense, saturated sands. The site is highly susceptible to liquefaction in the event of the design earthquake. Our primary geotechnical design concern was the possibility of bridge collapse resulting from a liquefaction induced slope failure against the deep foundation at the abutment. A combination of limit equilibrium and displacement based analysis techniques were used to assess the problem, and to estimate the shear and moment demands on the new large diameter CIDH pile foundation. By installing a single row of stone columns at the mid-height of the abutment slope, we were able to demonstrate that the estimated lateral load resulting from liquefaction would not exceed the plastic capacity of the proposed deep foundation. Our approach was generally consistent with the recently published, and AASHTO sponsored, NCHRP 12-49 project regarding seismic design guidelines for new bridges and the effects of seismic displacements against bridge foundations.

One part of the NEES portfolio is two permanently instrumented field site for monitoring soil-foundation-structure interaction (SFSI), ground motion, ground deformation, and pore-water pressure response to both active and passive seismic sources. The two sites, the Garner Valley Downhole Array and the Wildlife Liquefaction Array, are located in the southern California region. Both sites have many years of previous monitoring history and have been well characterized. These field sites will be used to monitor response generated by local and regional earthquakes and for active experiments-using shakers. A reconfigurable steel-framed SFSI test structure is being constructed at the GVDA site and instrumented with sensors installed in the structure, foundation, and underlying soil. The focus of this simple structure is the study of the physics of SFSI without the complexities of "real" structures. This pair of NEES field sites will also provide an excellent bed for new in-situ site characterization techniques and new sensor technologies. Data from both sites will be contributed to the NEES Data repository and the advanced National Seismic System.

The Third Avenue Bridge over the Harlem River links Manhattan to the Bronx. The rim bearing swing span bridge was constructed in 1898 and is in need of complete reconstruction to eliminate structural deficiencies and meet current traffic requirements as well as satisfy the seismic safety guidelines set forth by the NYCDOT. The new center bearing swing bridge, when reconstructed, will have a swing span of about 108 meters. Most of the piers and their foundations will be replaced. The critical center pier will be retrofitted using ten 6-ft diameter drilled shafts socketed into bedrock. Several major challenges regarding the design and construction of the replacement bridge were encountered. The existing center pier is founded on a hollow cylindrical caisson, which is partially embedded in the soil profile and does not rest on bedrock. This pier was found to be inadequate to carry the design seismic loads. The swing span mechanical system has minimal tolerance for permanent settlement and tilt of the foundation. This paper presents the details of the new bridge and its site conditions, followed by the seismic geotechnical engineering analyses performed to develop the foundation retrofit design for the center pier.

Pseudo-static analysis of seismic performance of an earth structure bases on the assumption of the synchronization of its peak responses with the peak ground acceleration. For a mechanically stabilized earth retaining wall, the acceleration, horizontal wall displacement, earth pressure, bearing pressure, and inclusion stresses depict its seismic response. Nonlinear finite analyses performed on a 10-m HTW wall show that all above responses peak synchronistically with the peak horizontal ground acceleration except the bearing pressure under simultaneous horizontal and vertical ground shakings.

A series of shaking table tests were performed at the University of Washington as part of a larger investigation of the seismic response of geosynthetic reinforced soil (GRS) slopes. The model slopes, 4 ft in height, were constructed with a wrapped faced at a slope of 63°. All were designed to have a static factor of safety of 1.0. The models were subjected to a sinusoidal frequency of 5 Hz on the shaking table. Model characteristics such as embedment length to slope height ratio (L/H) and geosynthetic spacing were varied in the testing program. Backfill settlement, significant lateral and vertical shearing in the reinforced zone, and development of a graben type failure wedge in the backfill behind the zone of reinforcement were observed. Test results indicated that as the L/H ratio and reinforcement strength increased and the reinforcement spacing decreased, the yield acceleration for the slope increased. A definite bi-linear failure surface was observed in all slopes. The results of the study indicate that GRS slopes are very safe in terms of their seismic resistance.

A two-story building was proposed within the Port of Los Angeles' (POLA) Pier 400 site, which was created by hydraulically placing dredged materials contained by perimeter dikes. The close proximity of the building to the dike could result in significant vertical and lateral movements of the ground surface during a design earthquake due to lateral spreading of the dike. A dynamic, two-dimensional, finite-element analysis performed near the site indicated that the lateral spread at the ground surface could be large near the edge of the building footprint during the design seismic event. The use of shallow foundations on improved ground was not permitted as the reviewing agency for the building design, the City of Los Angeles Department of Building and Safety (LADBS), would not allow large movements of the shallow foundations or a floating mat foundation. The design team selected pile foundations and lateral pile analyses were performed to determine the bending moments and shear forces within the piles due to varying lateral spread of the liquefied hydraulic fill surrounding them. The lateral spread estimates were made using simplified Newmark analysis, and an iterative scheme developed whereby shear forces developed in the pile were used to estimate the "pinning" effects of the piles, which were in turn added to the residual shear strength of the hydraulic fill. The total number of piles needed to reduce the lateral spread was determined so that the maximum moment within a pile would remain within its elastic limit, as required by the LADBS. The design procedure took advantage of pile pinning effects through the use of a simple analytical approach to achieve the project goals and gain acceptance by the LADBS.

Scientists estimate that there is a 9-in-10 chance of a magnitude 6 to 7 temblor occurring in the New Madrid Seismic Zone (NMSZ) within the next 50 years. Due to the presence of the deep soil and the closeness of the faults to the studied sites, the site response is different and worse than those provided in National Earthquake Hazards Reduction Program (NEHRP) (1997). A major task is to characterize the site and evaluate the dynamic soil properties using field tests. Three different field tests have been used to study the maximum shear modulus: seismic cone penetration, cross-hole velocity, and spectral analysis of surface wave (SASW). Meanwhile, an empirical equation, using results from laboratory tests, was used to compare and calibrate the field test results. Since deep soil is the typical feature of the NMSZ, attention is concentrated particularly on the effect of confining pressure on the variation of shear modulus and damping ratio with wide range shear strain (10^–6–10^–1). The results are compared by different methods. The typical curves of strain dependent modulus degradation and damping ratio at different confining pressures are presented. On the aforementioned results, the influence of confining pressure on the seismic site response in deep soil is analyzed accounting for the near-fault effect.

The paper investigates the role of soil in the collapse of a 630m segment (Fukae section) of the elevated Hanshin Expressway during the severe Kobe earthquake of 1995. There is evidence that soil-foundation-structure interaction (SFSI) played a detrimental role in the performance of the system. There were 18 spans in total, all of which suffered a spectacular failure and transverse overturning. Several factors associated with poor structural design have already been identified. The scope of this paper is to complement the earlier studies by examining the role of soil in the collapse. Results indicate that the role of soil in the collapse was triple: (1) it modified the bedrock motion so that the frequency content of the resulting surface ground motion became disadvantageous for the particular structure; (2) the compliance of soil and foundation altered the vibrational characteristics of the bridge and moved it to a region of stronger response; (3) ductility demand on the pier was higher than the ductility demand of the system. The increase in seismic demand on the piers may have exceeded 100% in comparison with piers fixed at their base. The above results contradict the widespread view of an always-beneficial role of SFSI.

Seismic response analyses were performed on 10- and 20-m hybrid cantilever retaining walls (HTW) with RC cantilever stem and mechanically stabilized earth (MSE). Geogrid is used as the reinforcement and is either attached or detached to the RC wall. The analysis uses the Imperial Valley Earthquake ground motion and its scaled motions to examine the effect of severity of earthquake-induced ground shaking on HTW seismic responses. Wall height, ground motion intensity, multi-directional shaking, and inclusion connection conditions were found to significantly affect the wall displacement and rotation, inclusion stresses, earth pressures, and bearing pressure of HTW. The earth pressure with multi-directional shaking differs from the AASHTO's Mononobe-Okabe (M-O) prediction.

This paper presents a simplified procedure for computing lateral spreading forces on bridge abutment walls supported on piles due to slope instability during earthquake shaking. This is a displacement-based method that takes into consideration the pile stiffness and the interaction between an abutment wall and the soil mass behind the wall. A curve of lateral spreading force versus displacement is first established for the soil mass behind the wall based on the Newmark chart that relates the standardized maximum displacement of the soil mass to the limiting acceleration coefficient. A second curve of lateral load versus displacement for the abutment wall supported on piles is then obtained by push analysis of the wall structure under the lateral spreading force. The intersection between the two load-displacement curves is computed as the lateral spreading force on the abutment wall. Results of analyses performed for one bridge are presented in this paper to illustrate the proposed method by considering pile-wall-soil interaction in a "decoupling" manner. It appears that the proposed method of accounting for the pile-wall-soil interaction can more satisfactorily predict the lateral spreading forces on abutment walls supported by piles than the conventional Mononobe-Okabe method.

Maximum magnitudes and peak horizontal accelerations were determined for earthquakes on 17 active faults within 160 km of the Hoover Dam Bypass Bridge. A 332-m-long Composite Concrete Deck Arch Bridge was designed on the basis of a nonlinear dynamic analysis using three-component seismograms at each skewback. A 1-s spectral acceleration of 0.139 g was selected as the target ground motion on which to anchor design earthquakes and response spectra. The target acceleration would be produced by a magnitude 6.2 earthquake on the Mead Slope fault at a hypocentral distance of 16 km, or by a magnitude 7.0 earthquake on the California Wash fault at 36 km. The smaller magnitude earthquake produced the maximum high-frequency motion, whereas the larger magnitude earthquake produced the maximum low-frequency motion. The design response spectrum for the river bridge was the maximum of the two motions. Synthetic, three-component seismograms at each skewback were produced with a Composite Source Model for use in a nonlinear dynamic analysis of the arch bridge. Input parameters for the model included fault locations, fault-rupture parameters (length, width, displacement, rake and rupture velocity), and seismological source parameters (seismic moment, stress drop, and Green's functions). Acceleration time histories were adjusted to bring their acceleration response spectra into close agreement with the design spectrum.

Design of motorway corridors in areas with high seismic activity require special consideration of earthquake related hazards, especially when long tunnels or bridges are foreseen. A 21 km long section of the existing Patras-Athens-Thessaloniki (PATHE) highway is realigned to cross a narrow strip of coastal land, which has been formed by the continuous action of an active fault. Seismic hazard considerations along with environmental and social constrains were the main factors for the selection of the preferred highway alignment and for the conceptual design of the various engineering structures along the highway alignment. The paper contains a presentation of the seismic hazard issues of the project and a summary of some of the design solutions adopted.

A section of the existing wharf and reclamation of the Kings Wharf in Suva, Fiji has been selected for an Upgrade to serve as a lifeline wharf in the event of an earthquake. The reclamation is retained by a 16 m deep sheet pile wall, tied back near the top and supported at the toe by a rock bund. The wharf deck is supported on 760 mm diameter prestressed hollow core piles and is connected to the reclamation by a series of bridging decks. The geology consists of a large depth (40 m) of soft soils. With excessive horizontal movements known to have occurred during construction, and with the knowledge of marginal stability from limiting equilibrium slope stability analyses, more sophisticated modeling was applied to better understand the stability concerns. The finite difference computer program FLAC was selected for this purpose. The objectives were to assess the stability of the existing wharf configuration under both static and seismic loading, and evaluate a proposed soil-cement improvement. The cement treatment is to be applied to a soil block 30–40 m deep and 14.5 m wide, immediately behind the existing sheet piles. The FLAC analyses showed that the cement treated block did address the deep-seated stability problem. However this also highlighted the effects of shallower movements in the rock toe bund causing structural distress to the piles. The soil-cement improvement was a necessary rehabilitation measure for limiting the displacements in the deep soft soils. Additional measures (reduction in rock bund height and infilling the hollow core piles) to address more structurally orientated shortcomings were also necessary.

This paper addresses the fault design issues associated with the IH-10 Katy Freeway Reconstruction project in Harris County, Texas. The project alignment in west Houston, Texas, extends from east of the IH-610/IH-10 interchange to west of Katy, a distance of approximately 20 miles. The project includes modifications to or reconstruction of four multilevel interchanges within the limits of the project. At two of those interchanges active growth faults have a significant impact on the design. Potentially impacted structures planned across the active faults include connector ramps, embankments, retaining walls, pavement, and bridges. Fault impacts mitigation is dependent upon the sensitivity of structures involved, the potential activity of the fault, and the ability to identify the fault zone in an urban environment where many features are obscured due to recent construction. Bridges located crossing faults were designed to accommodate differential. Key elements of the structure's design include the width of the primary and secondary hazard zones, the dip angle of the fault, and the horizontal angle of the roadway with the strike of the fault.

A theory based on the pore collapse concept applied to cylindrical cavity expansion is developed for evaluating Dynamic Cone Penetration (DCP) resistance and predicting Dynamic Cone Penetration Index (DCPI) in c-φ soils. A closed form solution for the penetration resistance and DCPI is developed. The present analyses assume the soil matrix to flow according to a rigid-plastic rule in the core region surrounding the cone. Thus, a free boundary defining the plastic domain develops and constitutes a part of the solution. The soil beyond that region is in its linear elastic state and is considered to have negligible contribution, since the mechanism governing the penetration is predominantly dependent on volumetric change due to pore compressibility. An energy balance criterion is utilized to calculate the DCPI, which is compared with experimental values observing good agreement. The effect of angle of internal friction φ, on penetration resistance/DCPI is much more significant than that of cohesion, c, especially at low initial porosity levels.

This paper summarizes micro-inch response of cosmetic cracks in a typical slab-on-grade ranch style house to both construction equipment-induced vibration and environmental (weather) effects. This structure was instrumented, and its response studied as part of the development of an Autonomous Crack Measurement (ACM) system. ACM systems are intended to record—with a single sensor—micro-inch crack displacements from both long-term environmental changes and transient construction vibrations for comparison in an understandable fashion. Ground motions were measured with velocity transducers, and micro-inch crack displacements were measured with LVDT displacement sensors. Construction within 14 m (45 ft) of the house involved trackhoe excavation fora 10 x 12 ft. reinforced concrete box culvert, chain trencher excavation for an 8-inch water service line, and vibratory compaction of trench backfill and granular sub-grade. As with many other studies of this nature, it was found that the weather induced crack response far exceeded that produced by construction vibrations even when produced by vibratory rolling within 3 m (10 ft) of the structure.

With the objective of examining the accuracy of electric cone penetration tests (CPT) performed in peat layers, we conducted tests to compare electric cone penetrometers with Dutch double tube cone penetrometers, which have been used conventionally. Test results showed that electric cone penetrometers demonstrated test accuracy equal to that of Dutch double tube cone penetrometers, and the following correlations were found: qmechanical = 0.85 qt for clay and organic clay layers and qmechanical = qt for peat layers ("qmechanical" refers to penetration resistance measured using Dutch double tube cone penetrometers [Dutch cone penetration resistance] and "qt" refers to penetration resistance measured using electric cone penetrometers [CPT resistance]).

Cone Penetration Testing (CPT) is one of the most flexible geotechnical and environmental in situ characterization techniques. Test methods and probing systems have been developed to determine a wide array of geotechnical properties and, more recently, to investigate environmental sites. Despite its many advantages, a major limitation has been refusal of the CPT probe in geologic layers shallower than the desired sounding depth. These layers can be cemented soils, such as caliche that is typically found in arid regions, coarse-grained formations (i.e., gravel and boulders), or volcanic flow fields. Refusal in these layers has historically resulted in the need to mobilize a drill rig to penetrate the refusal layer and continuation of the investigation through a cased borehole. This increases cost and the detailed CPT profile of the site stratigraphy is lost. To address this limitation, we are developing the Enhanced Access Penetration System (EAPS). This paper describes our investigation of laser and overburden drilling as potential techniques to integrate with CPT for penetrating hard layers. We conclude that laser drilling is not currently feasible and that air rotary drilling is the preferred overburden drilling method. A prototype EAPS incorporating air rotary drilling is described. The system allows characterization, sampling, and drilling tools to be exchanged down-hole, without removal of the rod string. Field test results from EAPS deployments at the Department of Energy's Hanford Site and at Umatilla Chemical Depot are also presented.

An experimental study and model performance of the stress-strain characteristics of decomposed granite soil was carried out using computer control GDS triaxial apparatus. Six drained triaxial stress paths were conducted, three on the compression side and three on the extension side. Hydrostatic compression tests were also conducted to evaluate the bulk properties of the soil. Laboratory tests showed the stress-strain and volume change behaviour for granite soils are highly stress path dependent. From the stress path test results, the Young's modulus and Poisson's ratio were quantified. The hierarchical (HISS) model, which is based on the theory of elasto-plasticity and elasto-viscoplasticity, has been used to characterize the behaviour of the granite soil. The computer program RESID1 has been developed to calculate the material parameters and to back predict the stress-strain behaviour of the soil. The stress-strain and volume change prediction characteristics were made using the hierarchical model and finite element method using Cam-Clay model constants. The model was validated using the experimental test results along different stress paths and the model predictions are found to be satisfactory.

This paper describes the use of the Marchetti flat dilatometer (DMT) on a major highway relocation project in Carver, Massachusetts (USA). Parts of the new highway span former cranberry bogs. Sheet piling was installed along both sides of the new highway alignment, and organic material was dredged from between the sheet pile walls. The area was then backfilled with sands. Since most of the sand was placed in a fairly loose state under water, liquefaction was a potential problem. Therefore, deep dynamic compaction (DDC) was used to density the fill. An extensive in situ testing program was instituted to characterize site conditions prior to densification, and to assess the sufficiency of the DDC after treatment. The results of this study suggest that the DMT can be used to provide accurate and cost-effective stratigraphic profiles. The DMT was particularly helpful in identifying pockets of organic soils (i.e., peat) that were not completely removed during the initial dredging operations. In terms of compaction QA/QC, the modulus values determined from the DMT appear to be very sensitive indicators of densification effects.

Since 2000, the Minnesota Department of Transportation (Mn/DOT) has designed and constructed selected transportation projects using design-build contracting. Design-build contracting combines, rather than separates, the design and construction phases of a project, and this is what differentiates it from the traditional design-bid-build method of contracting. With the advent of design-build, a debate began within Mn/DOT regarding when the geotechnical exploration should be performed in the process, who should perform the geotechnical exploration, and who would assume the responsibilities and risks of the geotechnical exploration. One side argues that a minimal geotechnical investigation should be performed to prepare the contract documents, leaving the responsibility and risk for the geotechnical exploration to the design-build engineer. The other side advocates performing, as completely as possible, the geotechnical exploration and analysis as part of the preparation of the contract documents, leaving the responsibility and risk to Mn/DOT or to Mn/DOT's consultant for the contract documents. This paper discusses the advantages and disadvantages of each side of the debate and the impacts on current design-build projects. The discussion includes the author's experience as the lead geotechnical engineer on the Trunk Highway 100 Segment 5 design-build team and as the lead geotechnical engineer for preparation of the contract documents for the Interstate 494 design-build contract.

Variable subsurface ground conditions present serious challenges to the civil engineering industry to design, construct, and maintain infrastructure. Accurate knowledge of ground conditions reduces project risk, improves construction performance, prolongs structure life, and prevents waste in over-design. NSA has developed systems that process collected seismic data using tomography and holography techniques to produce detailed, three-dimensional representations of subsurface conditions. Seismic signal waveforms traveling through a complex medium consist of various arrivals from refractions, reflections, scattering, and dispersion. Tomography and holography are proven inversion technologies for estimating location and extent of material property variations causing changes in signal waveforms. This paper will present three case studies describing the types of geotechnical investigations performed by NSA.

Designing geophysical investigations for transportation related projects requires special attention to the constraints imposed by right-of-way, irregular topography, noise from traffic, and the need to avoid the interruption of traffic flow. A geophysical engineer needs to be prepared to consider these design issues that are not addressed in a standard procedure such as ASTM D-5777. The author presents design strategies that address these issues, and illustrates the concepts with case histories taken from bridge and highway projects. Beam steering, broadside shooting, and non-traditional designs that preserve alternative analysis options are presented. Transportation engineers who augment traditional subsurface geotechnical surveys with engineering geophysics are better prepared to avoid costly delays and redesign of projects due to differing site conditions.

In March of 2002, a depression was discovered in the eastbound lane of SC22 near Conway, South Carolina. Within hours, a hole developed that revealed a void beneath the asphalt pavement approximately 8 feet deep by 10 feet wide. As a safety precaution, the SCDOT filled the void with flowable fill and patched the asphalt while further investigations were conducted. Further investigation revealed that a collapse type sinkhole had developed beneath the relatively new roadway. Geophysical testing data along with several Soil Test Borings were performed to evaluate the potential cause of the sinkhole as well as potential for future sinkhole development in the area. Although the potential for sinkhole development has always existed in the area due to the Coquina Limestone that underlies the relatively thin overburden, the absence of large-scale development has limited the occurrence of sinkholes in the area to subsidence type. As many of these sinkholes go unreported or unnoticed, this phenomenon is not well understood in the immediate area. Using the field investigation tools available, potential solutions to this sinkhole have been developed as well as precautionary measures to reduce the risk exposure as large-scale infrastructure projects continue to be constructed throughout the area.

Meta-stable soils (i.e. those prone to collapse) occur worldwide, resulting in soil collapsibility being a global problem. Such soils can be naturally occurring or man made, and loess, one of the most common natural collapsible soils (often found underlying areas of infrastructure) covers over 10% of the Earths surface. In-situ properties are often variable and difficult to predict, so effective site investigation is essential for the optimum characterisation and prediction of soil behaviour, and for the planning of ground improvement strategies prior to development of such sites. Recent work has shown the potential of geophysical methodologies to provide useful information on collapsible soils, overcoming some of the limitations of purely geotechnical ground investigations. New developments have also been made concerning techniques used for the subsequent ground improvement of such sites. This paper outlines the problems associated with collapsible soils and, using case studies from the UK and Africa, highlights the potential of geophysical seismic and resistivity methods to successfully investigate soil properties, including assessment of ground improvement work. The paper also presents an example of recent fieldwork from Eastern Europe where a new dynamic compaction methodology has been successfully used for ground improvement on collapsible soil.

A seismic crosshole tomography system for characterization of the subsurface at bridge sites in mantled karst terrane was evaluated in this study. There is great need for a reliable testing method to map competent rock and estimate pile tip elevations during design of a structure. Field data presented for a bridge foundation site were compared against material profiles available from geotechnical drilling. Crosshole profiles were found to match layering structure of drilling data. Based upon these findings, it can be concluded that seismic crosshole appears to be technically feasible for developing basic layer structure and top of rock profile in karst terrane.

Highway construction often requires the placement of embankments and earth retaining walls to facilitate grade separations. Instability and settlement occur when these structures are placed on top of weak and compressible soils. Historically, the severity of these problems has been reduced using toe berms and surcharging. More recently, Rammed Aggregate Piers^TM have been used to avoid the need for extending large right-of-ways required for toe berm construction or for time-consuming surcharging. The installation of Rammed Aggregate Piers reinforces weak and compressible foundation soils prior to construction of earth embankments and walls. The installation of Rammed Aggregate Piers increases the factor of safety against slope instability as a result of the high angle of internal friction (48 to 52 degrees) achieved during ramming and reduces the magnitude and time of settlement by increasing the overall stiffness of the foundation soils and providing a drainage pathway for dissipation of excess pore water pressure. This paper presents analytical methods used to design Rammed Aggregate Piers to reinforce weak soils and control settlements below highway and railroad retaining walls and embankments. The analytical methods are illustrated by a case history for a Mechanically Stabilized Earth (MSE) wall support project near Houston, Texas. This work is of particular significance because it presents design methodologies and a case history for an effective ground reinforcement technique increasingly used to support highway embankments and walls.

California State Route 73, also known as the San Joaquin Hills Transportation Corridor, is a 24-km long toll highway connecting the cities of San Juan Capistrano and Newport Beach, in Orange County, California. The design/build project included 78 structures and more than 12 km of retaining walls and sound walls. Structures range from 1- and 2-span bridges to connecting structures spanning over 0.8-km with 13 support locations. Special designs were required to span zones of loose, wet alluvial soils. One of the interchanges located at Laguna Canyon Road incorporated two ramps to be constructed over a (proposed) drainage culvert. Soil investigations revealed that underlying deep alluvial soils possessed both a static settlement potential, and a dynamic consolidation potential in excess of Caltrans' design criteria. Several remedial construction approaches were considered, although the presence of a critical water supply pipeline in the proposed construction area narrowed the method selection to "low-impact" techniques. Compaction grouting was selected upon completion of a test section, and included treatment of the alluvial profile at a 1:1 projection from the proposed culvert structure. Precision monitoring of the buried water supply line was required during proximal grouting treatment. Project totals included 921 grout injection points, 3,360 m³ of limited mobility displacement grout and more than 14 km of grout casing installed. Average post-treatment CPT "n"-values were well in excess of project specification minimums.

The Victory Bridge replacement project in Perth Amboy, NJ involves a new high-level structure, the southern approach embankment to which will be supported on Vibro Concrete Columns (VCC) installed through existing fills over loose sands and organic deposits. Three major design issues with the approach fills and associated retaining walls were: large expected total and differential settlements due to organic soil consolidation; seismically-induced large settlements and slope failures anticipated due to liquefaction of the loose saturated sands during the design earthquake; and a tight construction schedule. Based on the evaluation of long-term performance, cost and schedule impacts, a design was chosen that included rigid support of the embankment fill using VCCs in conjunction with a reinforced soil-high strength geosynthetic base mat. The rigid concrete columns bear on the deep dense sand. The economic design enables a high level of performance during a seismic event, reduces differential settlements between the pile-supported abutment and roadway, eliminated the need for piles to support a retaining wall, and can readily be accomplished within the project schedule and site constraints. Construction is underway and will be reported upon in detail in a future paper, however this paper contains design considerations and general construction information.

Compensation grouting has been attracting attention in recent years to control ground settlement caused by underground construction or deep excavation. A successful and effective application of compensation grouting depends not only on utilization of a sophisticated monitoring system in the field during grouting process but also on a fundamental understanding of grout soil interaction. Laboratory grout injection tests were performed on kaolin clay to investigate the effect of over-consolidation ratio and grout type on the effectiveness of compensation grouting. The experiments involved injection of various grouts into a clay specimen consolidated in a modified consolidometer, which has an injection needle installed from the base into the specimen. This paper also presents the results of two case histories where compensation grouting was used. The first case was carried out during shield tunneling work conducted in alluvial clay deposits in Koto-ku, Tokyo to investigate the effectiveness of compensation grouting to reduce surface settlements. In the second case history compensation grouting was used behind diaphragm wall to reduce the settlement of buildings during a deep excavation constructed in Shanghai soft clay. The variation of brace force and ground settlement with corresponding grouting pressure and construction sequences were recorded during the construction. Numerical simulations of these case histories are presented.

The East Side Access tunnel Project in New York City will connect Long Island Rail Road in Queens to Grand Central Terminal in Manhattan. The Queens segment of the project comprised of cut and cover and bored tunnels. The site in Queens primarily consists of glacial deposits with cobbles and boulders with high groundwater table. Construction of a proposed approach structure in Queens includes a combination of slurry walls and jet grout plugs for base stability and groundwater control of the excavation. The plugs are made of overlapping jet grout columns. This paper presents and discusses the results of a finite element analysis carried out to better understand the interaction between jet grout columns, glacial till and slurry walls and aid the design of jet grout plugs.

The paper describes geotechnical investigations, design, construction, and performance evaluation of a grouting program completed to support a new railroad truss bridge over an Interstate highway in Pennsylvania. A large two-span truss was required to carry a local main for the Norfolk Southern Railroad across I-76 (Schuylkill Expressway) and new ramps. The construction project was required to improve access to I-76 from US Route 202 and US Route 422 in King of Prussia Pennsylvania. A geotechnical investigation indicated limestone rock below 15 to 20 m of medium clay. The clay was not suitable to support the high loadings imposed by the railroad bridge. The limestone was found to have frequent solution cavities on the order of 0.5 to 2 m in size, to depths of more than 30 m. The design solution was to grout the upper 3 m of the variable quality rock to form a mattress of stable rock to support driven piles over the deeper poor quality rock. The design used limited mobility displacement grouting. The paper presents technical details of the conditions encountered, design approach, construction observation and grouting data, and an analysis of the grouting records to indicate the performance of the grouting.

A compressible inclusion in the broadest sense of the term is any relatively compressible material that is intentionally placed between, a rigid and/or non-yielding structure and the ground that would otherwise be in direct contact with it. This allows the ground to yield or displace. The primary benefit is reduced earth pressures acting on the structure which can either reduce the cost of a new structure or enhance the performance of an existing one. This paper outlines the basic ways in which modern, engineered compressible inclusions are used with earth-retaining structures to produce controlled yielding and predictable results. Typical materials used, which nowadays are usually some type of geofoam geosynthetic, and specific transportation-related applications are also described. Because of the diversity of applications and the fact that there are usually multiple benefits to using them, the use of geofoam compressible inclusions has the potential to significantly and permanently impact they way in which earth-retaining structures are designed, constructed, maintained, rehabilitated, and upgraded.

Ground modification technologies—are we using the right quality control tests to ensure that performance objectives will be satisfied? Construction of transportation and infrastructure systems over the past several decades is replete with applications of new ground improvement technologies. Many of these new technologies are patented and/or require specialized equipment and contractors. Owners are often at a disadvantage to judge the performance of the many types of ground modification available. The need for QC/QA and its integration with design and performance criteria are explored and discussed. Following background development and definitions, a conceptual framework for linking QC/QA with performance-based criteria for ground modification techniques is proposed.

Vacuum consolidation is a soil improvement technique that accelerates construction on soft ground by using the action of the atmospheric pressure in combination with a ground pore-pressure relief system. As an alternative to the conventional preloading (physical surcharge), vacuum assisted consolidation can be used to consolidate soft alluvial soils, to improve bearing capacities prior to construction, and to reduce post-construction settlements. This paper presents case history of roadway embankments of 3.3 to 7.9 m high on three marshland sites using vacuum consolidation technology. Lack of shear strength of the soil at the project site did not allow construction of embankments without soil improvement. Although the use of conventional wick drains and subsequent application of surcharge was sufficient to solve the consolidation problem in most areas, in some specific areas a different approach was needed because of acute slope instability combined with strict construction schedule requirements. Vacuum consolidation was applied in three sites with recent alluvial clayey soil deposits. In addition, the sub-soil was fully instrumented with a number of pore pressure, multi-point settlement gauges and inclinometers for real-time monitoring of the embankment during construction at the marshland zones. The details of design and site monitoring program along with post-construction performance for three sites are presented here.

The Colorado River Bridge is a key element of the 5.6 km (3.5-mile) U.S. Highway 93 Hoover Dam Bypass Project from Clark County, Nevada, to Mojave County, Arizona. The Central Federal Lands Highway Division of FHWA is the managing partner responsible for project delivery. The planned 579 m (1,900-foot) long Colorado River Bridge will cross a rugged bedrock setting in Black Canyon, 460 m (1,500 feet) downstream of the historic Hoover Dam and 274 m (900 feet) above river level, with a 332 m (1,090-foot) main arch and seven approach spans. Various alternative bridge types were evaluated for the site based on aesthetic, technical suitability and cost criteria; the selected design includes steel box girders, composite concrete deck, and reinforced concrete arch rib and pier columns, foundations and abutments. Geotechnical characterization of the bridge site and particularly the skewback foundations required a specialized approach in the rugged bedrock environment, including 3-D laser scanning of the canyon walls, geologic mapping by multiple methods, core drilling with specialized rigs/access equipment, optical televiewer borehole logging of rock fracture data, in-situ borehole jack testing and down-hole seismic surveys, and laboratory testing of rock strength. Geology of the bridge site consists of Tertiary-age volcanic and sedimentary rocks, with the key skewback foundation areas composed of variable quality but generally low-strength massive tuff and strong but highly irregular basalt dikes.

The states-of-practice for performing remedial ground densification and evaluating earthquake liquefaction potential of loose saturated sands have evolved relatively independent of each other. This is in spite of the fact that the induction of liquefaction is typically requisite for remedial ground densification of sands. Simple calculations are presented herein for estimating the mechanical energy required to densify a unit volume of clean, loose sand using deep dynamic compaction, vibro-compaction, and explosive compaction. These computed energies are compared with that required to induce liquefaction during an earthquake using the Green-Mitchell energy based liquefaction evaluation procedure. The comparison highlights the importance of the efficiency of the method in which the energy is imparted to the soil and the importance of the mode of dissipation of the imparted energy (e.g., possible modes of energy dissipation/expenditure include: breaking down of initial soil structure, ramming soil particles into denser packing, and radiating away from the treatment zone). Additionally, the comparison lays the preliminary groundwork for incorporating the vast knowledge base gained from fundamental studies on earthquake induced liquefaction into the design procedures of remedial ground densification techniques.

Geotechnical aspects were critical elements of the successful construction for the Route 21 Viaduct in Newark, New Jersey. The original viaduct and interchange were structurally deficient and functionally obsolete and needed replacement. The project objective was to design and construct the replacement to the existing Route 21 Viaduct and the adjacent interchange while maintaining traffic flow throughout the construction period. Difficult subsurface conditions at the site that included a layer of weak and highly compressible layer of soft organic silt and peat complicated the construction of the project. A significant ground improvement program was required for the soft soils to permit the construction. Ground improvement was needed to reduce post construction settlements and increase the stability of the new embankments and retaining structures. The preloading program included extensive geotechnical instrumentation to control fill placement and evaluate the performance of the ground improvement. This paper discusses the ground improvement aspects of the project and presents the findings of the ground improvement program. It also highlights the key issues that affect the successful implementation of the different geotechnical aspects of the project. Design, construction and economic issues are discussed in the paper.

A portion of a new light rail system was to be located over a previously filled-in swamp. Although existing freight tracks crossed the area, construction of the passenger station would result in an increase in grades of 2 feet in the platform area and 9 feet in the parking area, which would induce additional settlement. Original settlement predictions were between 2 and 4.5 inches in the platform area, but as high as 24 inches within the parking area. Initial proposals were to install wick drains and surcharge throughout the entire site. However, as a result of construction priorities, the site was going to be used for stockpiles of excess soil from other portions of the project. Surface settlement monitoring points were installed throughout the site prior to build-up of the stockpile, taking advantage of any settlement that would occur due to the stockpiled material. This paper describes how this need for early storage of excess soil materials created the opportunity to use several different ground improvement methods for the control of post- construction settlement. Those methods included wick drains and surcharge where still required, the continued use of only surcharge, and low-density cellular concrete fill (LDCCF).

A considerable part of Bangladesh, especially the southern part near Shunderban, the world's largest mangrove forest, is covered by deep-seated soft to very soft soils. A major road is being constructed through this soft deposit in Mollahat-Noapara at Bagerhat connecting the capital city with the southern part of the country. Several boreholes were drilled at the project site along the road section for soil characterization. SPT-N values were measured for at least 30 m at the interval of 1.5 m down each borehole. Both disturbed and undisturbed samples were collected from various depths. Various laboratory testing were conducted on these samples. Based on test results, a settlement of 336 mm was predicted at the project site under the future traffic load in 180 days. In order to develop a proper methodology regarding the improvement of underlying soil at the project site, two trial sections were constructed along the road section and was subjected to preloading to bring about the predicted settlement as quickly as possible. It was observed that the average settlement due to preloading after 180 days was 220 mm. SPT-N values and compressive strength measured after preloading were increased considerably.

Slope stabilization using vertical piles has been used many times over the last thirty years to correct slope stability problems. An adequate design method for this means of stabilization must include a determination of the improvement in the stability of the slope as well as a determination of the displacements and stresses in the stabilizing piles. Many diverse methods of analysis have been proposed in the relevant civil engineering literature. A brief discussion of the current design methods is included, with a tabulated summary. Following the summary of design methods, a simple slope configuration is selected and analyzed using the finite element method. Based on this analysis, it is concluded that the finite element method appears to be an effective means to analyze this difficult problem. Typical finite element analysis results are presented and discussed.

Cut and fill earthwork activity associated with construction of highways and buildings in steeply sloping terrain through landslide deposits is difficult and involves enhanced levels of risk. Quantifying the risk of failure using conventional deterministic slope stability analyses may not adequately address the inherent uncertainties that are often encountered in these areas, which typically include significant spatial variability of the subsurface geomaterials, and geologic anomalies that may be difficult to identify in traditional subsurface geotechnical investigations. A practical reliability-based approach is described and applied to a slope failure that occurred during construction of a roadway and development near the town of Big Sky, Montana.

Missouri has recently experienced below expectation performance or "the bump-at-the-end of the bridge" phenomena at bridge approach slab transitions. Information on approach slab performance was collected state wide to assess if the problem was limited to regional or geological distribution. Finite element analysis was then used to explore the soil embankment-bridge structure differential settlement in two Missouri bridges; MoDOT Bridge A6031 in Livingston County, and MoDOT Bridge A5834 in Pulaski County. These two cases are indicative of the types of soil conditions encountered in the Northern Glaciated Plains region (deeper compressible foundation soils) and the Southern Ozarks region (shallow rocky clays) of Missouri. The construction sequence was tied to the analysis by applying the embankment and slab loading following the construction records. The finite element method results compared well with observed displacements. Recommendations for construction sequence are provided.

The use of block-molded expanded polystyrene (EPS-block) geofoam as a lightweight-fill material for highway embankments is a relatively mature geotechnology with more than 30 years history of successful application worldwide. Basic analysis and design procedures are now well established and documented, and current research and development efforts are focused on making incremental improvements. One such area of improvement relates to analysis and design for seismic loading. The recent construction of several EPS-geofoam highway embankments on the Central Artery/Tunnel (CA/T) Project in Boston, well known as the `Big Dig', resulted in an opportunity to advance the state of practice for EPS-geofoam embankments subjected to seismic loading. In particular, a newly recognized behavioral mode referred to as seismic rocking was identified and found to govern the design of these fills for internal stability. This behavioral mode is described in this paper in the context of summarizing the current state of knowledge with respect to seismic analysis and design of EPS embankments.

Interferometric Synthetic Aperture Radar (InSAR) was used to monitor ground movement in Badlands National Park. InSAR is an innovative method that can be used to detect, map and measure movement without the need of survey targets or ground-based instruments. Using current and historic data sets, InSAR was applied in observing landslides that impact the Park's access road, and in evaluating possible alternate alignments. Although traditional geotechnical instruments have monitored the road for years, the total area assessed using InSAR is larger than could practically be studied by these instruments. The results are on an interactive website and show that nearby landslides are not interrelated, the boundaries of a large, slow moving landslide agree with data from instruments and observations, and the amount of movement occurring along the existing alignment may be typical for the area. Availability of historic data, unexplainable ground movement and low coherence were some difficulties encountered.

In doubling the width of I-95 as part of the Woodrow Wilson Bridge replacement project, 24 to 36.5 m wide embankment extensions that are 3 to 7.6 m in height are being constructed over very soft alluvial organic clay that is 4.5 to 9.7 m thick. There will be considerable (0.6 to 1.5 m) primary consolidation and secondary compression in the soft organic clays. To hasten the time to the end of primary consolidation, Pre-Fabricated Vertical Drains were installed throughout the mile long project area. However, project criteria limits on long-term settlement which would occur due to secondary compression required extensive design analysis to assess surcharge thickness needed. In 20 years, not more than 5 cm differential settlement at bridge structures, and between the existing roadway and pavement on new embankment is permitted. This paper discusses the methods used to predict secondary compression settlement in the soft organic alluvial clay due to the embankment loads within the compressed construction schedule, and determine requirements for surcharge thickness to meet project differential settlement limit criteria. The paper also demonstrates the use of AAOS in planning transportation construction over soft clay.

The Cedar Heights community is a private subdivision located in the foothills west of Colorado Springs, Colorado. At one location within the subdivision, approximately 10 meters of fill was placed over an existing landslide during road construction in 1980. During extended wet periods in the spring of 1995 and the spring of 1998, the landslide reactivated through the road fill material. The road was repaired after the failures to re-establish the roadbed. A geotechnical investigation during the summer of 1998 identified two separate slide surfaces below the road. Subsequent to the investigation it was determined that the landslides would not be stabilized. Therefore a real-time landslide monitoring and emergency notification system was installed to provide for the safety of the public which would traverse the landslide. The design of the landslide monitoring and emergency notification system is presented in this paper.

The desire to monitor a section of coastal bluff for slope movements along the North County Transportation District/Amtrak tracks in Del Mar, San Diego County, California led to the development of a continuous monitoring system along approximately 1000 m of track. Because of the length to be monitored, the use of conventional single-point monitoring systems such as multiple tiltmeters or in-place inclinometers (IPIs) was deemed impracticable. Since bluff failure could occur anywhere along the track, the use of single-point instruments would require a large number of instruments, with the possibility that a movement could still occur between points and be missed by the monitors. Instead, it was proposed to install horizontal time domain reflectometry (TDR) coaxial cable sensors along high-concern segments of the track. The TDR monitoring system works similar to radar. It uses a coaxial cable as a sensor grouted in a trench between the bluff edge and the tracks. Any slope movement will deform or shear the cable at the location of movement. A reflectometer sends a voltage pulse along the sensor. When the pulse encounters a deformation, or the end of the sensor, some or all of the energy is reflected. The amount of reflected energy is proportional to the extent of the deformation with all energy reflected from the end of the sensor. The reflectometer accurately determines the location of the deformation and the relative extent of movement as noted by the magnitude of the reflection. The Del Mar Bluffs TDR monitoring system used three on-site dataloggers and reflectometers to monitor three different sections of the bluff. Each reflectometer was connected to two sensors about 175 m long through a multiplexer. The sensors were pulsed every several minutes to determine if sensor deformation had occurred. In the event of a deformation, a signal was sent to a central monitoring unit where an automated telephone dialer notified railway personnel of possible bluff movement. Personnel could then contact the system by telephone and determine the location of the cable deformation so that a safety inspection of the bluff and track could be made.

A proposed multi-lane cross-city corridor called for grading through an area of numerous deep-seated landslides. The grading plan design called for construction of a 1.5:1 (horizontal: vertical) to 2:1, 45 m (150 ft) high cut slope descending from a multi-media receiving facility to the proposed corridor road. The proposed design required an exception to the Uniform Building Code and the City of Santa Clarita Building Code slope requirements. Relocation of the media facility was not feasible due to line-of-site transmission requirements and realignment of the roadway was fixed due to property constraints. A cost effective solution using a combination of sequenced shear keys, geogrid-reinforced buttress fills and soldier piles was designed and constructed at an accelerated schedule. Prior to and during construction, several techniques were used to minimize potential damage to any nearby structures.

Time domain reflectometry (TDR) has been used in the past to locate and estimate movements in landslides encroaching highways. As part of this study, further research of TDR and landslide monitoring was performed to evaluate if readings obtained from TDR can be correlated with the amount of movement along a slide plane. Field measurements obtained using side by side or nearby slope inclinometers and TDR cables were compared. In addition, laboratory tests were carried-out using a cable shear-testing device designed to simulate the slide plane conditions found within a landslide. The following issues were examined in relation to both the field and lab studies: (1) the amount of slide plane movement required to detect a TDR reflection reading in the cable; (2) the amount of movement associated with a TDR reflection as the slide mass continues to move; and (3) the influence of installation conditions on TDR readings. Based on the results of this study, tentative relationships between slide plane movement and TDR reflection readings are discussed. However, these relationships depend upon cable type, grout strength, and soil at the shear interface.

In the arid regions of the southwest United States, engineers have taken advantage of the strength characteristics of unsaturated, weakly cemented soils for many years. Undisturbed soil is difficult to sample and test in the laboratory. In the past, in situ methods typically consisted of down-hole seismic. The US 70 Hondo Valley Project in New Mexico presented a unique opportunity to compare the results of triaxial tests on unsaturated soil with the results of in situ testing via pressuremeter testing (PMT) in these deposits. Using a numerical analysis approach, we were able to estimate the effective friction angle and cohesive strength of unsaturated, weakly cemented soil via PMT. We completed the design of excavations within the unsaturated soils based on observations of the existing cuts, the results of triaxial tests on unsaturated samples, and in situ PMT testing. We found what engineers have intuitively known for years: that the design of new excavations based on the past performance of cuts in the same soils is a valid design approach. Reliable safety factors for new cuts are difficult to estimate without the benefit of lab testing on undisturbed samples, in situ testing, or prior slope failures. Moreover, the PMT numerical analysis approach for estimating both the frictional and cohesion component of the strength of unsaturated soil compares well with the strength estimates on samples tested with triaxial loading under unsaturated conditions.

The reconstruction of Interstate 15 in Salt Lake City, Utah required extensive high fills and high retaining walls over soft foundation soils to both raise and widen existing embankments and to construct new embankments. The paper describes the type and interpretation of geotechnical instrumentation used to assess foundation performance during construction. Data are presented for a 9.5 m high embankment and a 16 m high MSE wall both treated with prefabricated vertical drains (PVD) and geotextile reinforcement. The methodology finally adopted to assess foundation stability focused primarily on the time rate of maximum horizontal displacement (dh_m/dt) and changes in the deformation ratio (DR = dh_m/ds), where s is the settlement under the embankment, as a function of the fill height. The installation of PV drains at spacings of 1.5 m or less caused significantly more settlement and lateral displacement without increasing the rate of consolidation.

Any construction activity involving compacted fills requires an understanding of unsaturated soil behavior. Unsaturated soils comprise three phases: soil solids and pores filled with water and air, whereas in saturated soils the pores are completely filled with water only. In over half of the world the water table is at a considerable depth, which means that the construction activity occurs within unsaturated soils. In such situations the vast majority of geotechnical problems arise from ground movements caused by variations in degree of saturation and suction. Construction of highways invariably involves unsaturated compacted materials. Elements of the pavement system, including foundations and embankments, are constructed under unsaturated conditions, which are subject to naturally occurring variations of moisture content and suction. In this paper, implications of changes in suction and moisture regime in highway foundations and embankments are analyzed and discussed.

It has been observed in many parts of the world that failure of slopes occurs during or after rainfall. The effects of precipitation and infiltration on the stability of slopes are studied by using the finite element method of computer analysis. The depth of infiltration is estimated and used to define the extent of an influence zone in the slope. It is found from the study that the mode of slope failure is a function of the soil strength in the influence zone. There exits a threshold value of strength that allows failure to develop within the influence zone at a shallow depth.

Ground surface vibrations and their effects on the adjacent ground were monitored during installation of a 20 m deep, sheet-pile wall at the excavation for the Lurie Research Center in Chicago, IL. The subsurface conditions consisted of 9 m of loose to medium dense granular soils and fill over a sequence of increasingly stiff glacial clays. The sheets were installed with two different vibratory hammers, and velocity transducers were placed at varying distances from sheets to record transient responses during the operation. The permanent deformation caused by installation of the sheeting was recorded with optical survey methods at 198 points. The results of the observations show that larger vibrations occurred during the start-up and shutdown phases of hammer operation than during its steady-state operation. Minor settlements occurred within about 12 meters of the sheet pile wall. The settlements were consistent with magnitude of the peak ground acceleration, about 0.1 g, that was computed from the time histories of the velocity traces. No damage to adjacent utilities was noted.

An innovative wall system with a reinforced concrete cantilever wall (or T wall) with mechanically stabilized backfill is proposed. The wall system, briefed as hybrid T wall (or HTW) retains the positive and removes the negative aspects of the performances of both reinforced concrete walls and MSE wall systems. HTW and its optimal dimensions were obtained inductively using the nonlinear finite element analyses through the seismic responses of six different wall types and varied HTW dimensions. Accelerograms of nine strong earthquakes of magnitudes between 6 through 8 Richter scale were used in the seismic response analyses of HTW. The strength of correlation between the seismic performances of HTW and earthquake strong motion parameters was investigated. The HTW performances were then expressed as the function of ground motion parameters with strong correlation through regression analyses for predicting the performance of HTW with known ground motion parameters and wall height. A comprehensive study is required to improve the wall performance prediction models.

This paper discusses the use of Mechanically Stabilized Earth (MSE) walls in ever increasing heights. Most MSE walls worldwide that exceed 20 meters high are constructed using metallic reinforcements in the reinforced volume. Design of tall MSE walls has much in common with design of lesser-height walls, but the performance of more detailed site investigations prior to design and the use of instrumentation monitoring during construction are critical to ensuring successful performance of these tall structures. Design features important to tall walls are described, and the paper cites several examples of completed tall MSE walls to demonstrate the international acceptance of such structures in major industrial and highway projects.

Systems of ground anchors are increasingly used to support steep excavation slopes and stabilize landslides. These ground anchor systems are comprised of a pattern of post-tensioned tieback anchors and multiple, isolated anchor pads or beams; they are less steep than tieback walls and do not have a continuous face, or a structure that penetrates the potential sliding surface. This paper addresses systems that contain up to 200 anchors, with individual capacities of up to 2000 kN, that have been installed in geologic settings ranging from shale to crystalline bedrock, and the associated soils. Observations are presented from the alternatives selection process, the investigation, design, and construction phases, and monitored performance of recent highway projects in the western United States. Specific design issues include analysis for anchor location, size, and length, bearing pad capacity and racking during tensioning and testing, desirable lock-off load, and corrosion protection. Specific construction issues include construction sequencing, allowable tolerances, and coordination with other items of work.

When a design was needed for a 50-foot tall retaining wall, the solution was achieved using the Retension^TM system, a precast concrete fascia with an attached precast concrete box. The box serves as a form for a cast-in-place concrete column. The wall was founded on a cast-in-place footing bearing on competent rock. Reinforced concrete was placed into the "form" made by the precast box. Two-rock anchors cast into the column stabilized the resulting pillar. Above the rock line, galvanized tie strips were added to the back of the fascia and connected to discrete metal reinforcing strips in a granular backfill matrix similar to a Reinforced Earth® wall. Advantages of the system to the contractor were cost savings due to the precast fascia units with precast "forms" attached, small footings and little backfill. This system is ideally suited for retaining walls in a rock-cut where only tied-back columns are needed, or partial rock-cut where tied-back columns are used in the lower strata and reinforcing strips in a granular backfill are added in the upper layer with no change in appearance to the fascia.

Until recently, traffic exiting Pittsburgh would use the West End Bridge to cross the Ohio River only to become entangled in the West End Circle, which consisted of two railway overpasses each out-of-alignment with the West End Bridge. A roadway improvement project involving the construction of a new railway bridge and highway underpass was undertaken to eliminate this traffic circle and provide a direct connection between the West End Bridge and State Route 19. Brayman Construction Corporation has since completed this project. This paper provides a summary of the design and construction sequencing of a temporary sheet pile excavation support system that was constructed to facilitate the completion of this project. The excavation support system consisted of opposing sheet pile walls (shoring and anchor walls) cross-tied with prestressed tendons beneath the railroad corridor. The general arrangement of this system is shown in Figure 1. The prestressed tendons limited the horizontal wall displacement to permissible levels specified by the railway owner, and the reuse of the phase one shoring wall as the shoring wall for the second phase of bridge construction eliminated the need to extract and re-drive sheeting, resulting in reduced displacements and construction time.

This paper presents a case study of the use of sheet pile retaining wall as a bridge abutment. The U type steel sheet pile abutment is investigated to determine their stability and behavior from numerical model study. The case study gives the effective application program, design method, and guide of a steel sheet pile abutment.

This paper presents the design and instrumentation case study of two caisson retaining walls for the T-REX Project in Denver, Colorado. A study of design methods available for caisson cantilever retaining walls indicated that uncertainties exist in selecting the appropriate load conditions, group reduction factors, and even the method of analysis for design of caisson retaining walls. Due to schedule and deflection constraints, the designers decided to utilize a computer program called LPILE to aid in the analyses. However, there was very little information available to aid in the actual use of LPILE to analyze caisson retaining walls. Due to this uncertainty, the design team decided to instrument several key caissons walls for lateral deflections in order to optimize the design process.

The reconstruction of Interstate Highway 74 (I-74) in Peoria and Tazewell County, Illinois will upgrade the geometric features of the roadway, improve the operational efficiency and increase safety. The proposed improvement poses unique design problems including widening from four to six lanes within the constricted City of Peoria Business District. This paper describes the retaining wall systems used to accommodate the proposed widening, the methodology for selection of wall types, and procedures employed for the wall designs. Details of the proposed wall construction are presented to illustrate the wall designs for differing soil conditions, restricted right-of-ways, and variable heights of roadway fills and cuts.

In this paper, the performance efficiency and stability of two full-scaled nailed structures were monitored and compared. In the first setup the nails are inclined above horizontal where the nail inclination is below horizontal in the second setup. Thus, the efficiency of the soil nailed walls with nail orientations above horizontal is observed. In the literature, the installation of nails above horizontal were neither mentioned nor applied. The analytical and field tests for the soil-nailed structures with nails installed at angles above horizontal gave better results in means of factor of safety with respect to the soil nailed structures with downward inclined nails.

The 11^th Avenue Railroad Underpass is located in Nampa, Idaho. The project involved replacing an old railroad bridge and narrow highway underpass beneath the main lines and switchyard of the Union Pacific Railroad with a wider, deeper structure. The new underpass extends to depths greater than 9.1 meters (30 feet) below existing grade, and about 7 meters (24 feet) below the estimated high groundwater level. A major constraint was that railroad traffic could not be interrupted through the site during construction. This and other construction considerations largely drove the design and led to the selection of structural slurry walls to provide both temporary and permanent excavation support and abutment walls. The new railroad bridge was preassembled in longitudinal halves on either side of the old bridge, and supported temporarily on structural slurry approach walls. Train traffic was shifted to one half of the old bridge. Construction of structural slurry wall abutments for the opposite half of the new bridge and demolition of the corresponding vacant half of the old bridge were then undertaken simultaneously. When the abutment walls were ready, the adjacent half of the new bridge was jacked laterally into position and placed on the new abutment walls. Train traffic was moved to the completed half of the new bridge, and the process was then repeated to complete the new bridge. After the railroad bridge was completed, the new underpass was constructed, in effect, by tunneling under the new bridge between the abutment slurry walls. This included demolition and removal of the existing underpass.

A consortium of contractors, engineers, and designers was assembled to plan, design, and construct an expansion of the Virginia Route 288 (VA 288) highway around Richmond's fast-growing western half. The project was approved for construction in December 2000 and construction started in April 2001. The project includes construction of approximately 17 miles of new highway with 23 bridges and overpasses. In keeping with the design-build spirit, the contractor proposed to shorten the bridge carrying Ramp G over Interstate 64 (I-64) by using high mechanically stabilized earth (MSE) walls. The north and south MSE walls needed to be 64 and 79 feet high, respectively. The construction of these walls reduced the number of bridge spans from five to two, saving an estimated $1 million in construction costs. The south wall, the highest abutment wall in Virginia, called for validation that it would adequately perform. To accomplish this validation, numerical analyses (using FB-Pier and FLAC) were performed to predict the short- and long-term behavior of both the walls and the bridge foundations. These analysis results were used to develop validation documentation necessary for final approval by the Virginia Department of Transportation and the Federal Highway Administration. An instrumentation and monitoring program was implemented during construction to evaluate the short- and long-term performance of the walls and pile foundations. Instrumentation included survey monitoring points, inclinometers, and strain gauges. Movement data collected from the instrumentation program indicate that the wall and bridge foundations are performing satisfactorily and within the general bounds of predicted movements.

This paper address the geotechnical design issues related to the IH-10 Katy Freeway Reconstruction project in Harris County, Texas. The project is being designed in ten sections by Section Design Consultants (SDCs) under the General Engineering Consultant (GEC). The geotechnical investigation was performed by the GEC in order to provide an early start for the geotechnical work so that this information would be available to the SDC's when they started work. An additional benefit to this approach is consistency of geotechnical design guidance between the various sections. The program design challenges related primarily to incorporation of an existing railroad right-of-way into the freeway corridor, fast track design and construction, and corridor confinement issues within the urban corridor. Technical issues related to the bridge design include differential settlement between pavement on new embankment adjacent to raised embankment and differential settlement due to phased fast track embankment construction. Corridor confinement resulted in the need to place a ramp at one interchange in a 32-foot deep cut/tunnel section, a unique approach to lateral support of the cut section retaining walls, and resulted in relatively deep detention ponds for the project. The need for expedited construction restricted design choices for solution of embankment foundation settlement and stability.

Underground space is an increasingly important component of urban infrastructure in cities throughout the world. Tunnels and deep open cut excavations are often developed in an already heavily built environment. The construction of these excavations has to be accomplished economically while minimizing adverse impact on adjacent structures. New analysis techniques are being developed to enhance the engineers' ability to predict these impacts. These techniques are also able to integrate measured performance during construction to improve predictions of performance due to later excavation activities. Robust application of these techniques requires accurate information on construction staging. This paper presents two new techniques, 3-D laser scanning and digital photogrammetry, which provides accurate record of progress of excavation activities. The accurate excavation data can be integrated with model simulation of excavation activities. These techniques can be used from significant standoff distances thus reducing the interference of personnel with earth moving activities.

On September 11, 2001, terrorists attacked New York City resulting in the collapse of the World Trade Center (WTC) towers. This event also severed a vital regional transportation link between New Jersey and lower Manhattan affecting nearly 67,000 daily commuters. On September 12, 2001, the Port Authority of NY & NJ (PANYNJ) set in motion, even as rescue efforts continued, plans to restore downtown commuter train service to its former Port Authority Trans-Hudson (PATH) WTC Station. This paper focuses on the Exchange Place Station Improvements Project, which was one of three components of PANYNJ's Downtown Restoration Program (DRP). Design of this project required underground rock excavations with spans upwards of 18 m (60 ft), rock cover as low as 7.4 m (25 ft) and existing buildings overlying planned excavations. Recommended ground support consisted of pre-stressed rock bolts, pre-fabricated lattice girders and steel fiber reinforced shotcrete (SFRS) linings.