GeoCongress 2006: Geotechnical Engineering in the Information Technology Age

Startling advances in microelectronics, sensors, computer power, communications, digital data analysis, data storage and visualization have been taking place during the last decades. Geotechnology is prepared to gain maximum benefit from the information revolution. Embracing information technology will trigger important changes in the way we teach, learn, investigate, conduct field studies, design and construct systems. New solutions cannot circumvent the fundamental physical, chemical and biological laws that govern the behavior of geomaterials. In this time of changes, we need our best engineering skills and ingenuity to explore new problem solving strategies.

This paper discusses spaceborne and airborne remote sensing, focusing on optical (satellite imagery, LIDAR) and radar (SAR) technologies and their application to geotechnical engineering and hazard assessment. Fundamental characteristics of these technologies and recent advances (e.g., hyperspectral sensing, radar interferometry) are summarized. One specific application of remote sensing, the use of high-resolution optical satellite imagery in earthquake damage assessment, is presented in detail. The analytical procedures used to identify earthquake damage from digital satellite data are introduced and applied to imagery from the 2003 Bam, Iran earthquake. The comparison between damage estimates derived from remote sensing and from field surveys are favorable for this earthquake, indicating that optical satellite imagery can provide detailed damage data for use in correlating damage patterns with soil conditions and estimating economic losses.

Stochastic data appear as basic components in reliability analysis and geostatistics. It is rarely emphasized that the multivariate probability distributions underlying random vectors (or processes, fields) are very difficult to construct theoretically, to estimate empirically, and to simulate numerically. This paper discusses the modeling and simulation of non-Gaussian random vectors, highlighting some useful geotechnical applications, important limitations, and outstanding challenges. Discussion is restricted to translation vectors, although emerging techniques that can potentially simulate a wider class of non-Gaussian random vectors would be briefly introduced for completeness. The translation approach is quite natural and takes advantage of the practicality, theoretical generality, and simulation speed associated with the multivariate Gaussian distribution. Nonetheless, there are fundamental limitations that must be recognized. The present focus on probabilistic analysis should be balanced by more research on statistical inference. It is acknowledged that statistical inference for correlated data is a challenging problem, but its practical significance is obvious.

The products of the Information Age give geotechnical engineers powerful tools to perform their work. One view of geotechnical engineering is that Information Technology (IT) tools may replace many of the functions that geotechnical engineers now perform. This view can be framed to argue that the right IT tools will even replace the need for engineering judgment. Since geotechnical engineers rely heavily on their engineering judgment to formulate and defend their arguments, this view would mean a major change in the way we do geotechnical engineering. This paper looks at geotechnical engineering in today's IT dominated world and considers ways that geotechnical engineering may change as the IT tools become increasingly powerful and pervasive. The paper's aim is to stimulate people's thinking about how we can make more effective use of IT tools in our future work. For experienced engineers, the result is insight to the important role of engineering judgment in an IT dominant world. For young engineers, the paper provides perspective on the role of IT tools in engineering practice and how they may develop their judgment skills. For non-engineers, such as owners, regulators and attorneys, the paper can help them better understand how geotechnical engineers think, or should think.

As a consequence of its particulate nature, soil exhibits a highly complex response to applied loads and deformations. Traditionally, geotechnical engineers have coupled continuum numerical analysis tools (such as the finite element method) with complex constitutive models to analyze soil response. This approach does not explicitly consider the particle-scale interactions underlying the macro-scale response observed in the laboratory and field. With increasing computational speeds, particle-based discrete element methods are becoming popular amongst geotechnical engineers in both research and practice. On a practical level discrete element methods are particularly useful for studying finite deformation problems, while from a more theoretical perspective they can be used to create virtual laboratories where the micro-mechanics of soil response can be analyzed in detail. This paper describes a series of validation studies that were performed to confirm that, despite their inherent simplifications, discrete element methods can accurately capture the macro-scale response of granular materials. It is shown that, once validated, these methods can provide useful information to explain the complex response exhibited by granular materials in conventional laboratory tests.

In recent years, engineering disciplines have begun to experience a revolution based on the use of information technology. In particular, the use of computer graphics and visualization have allowed engineers to gain unprecedented insight into both spatial and abstract datasets, resulting in better designs, more in-depth understanding, and more efficient analysis. In this paper, we argue that many engineering datasets are best visualized in three dimensions because of their inherent three-dimensional (3D) spatial properties. Traditional 3D visualizations are still limited, however. In order to mitigate these limitations, we describe two additional technologies that will further increase the benefits of 3D engineering visualizations. First, immersive virtual environments (VEs) allow an engineer to "get inside" the data and view it naturally, resulting in greater spatial understanding and potentially greater insight. Second, interactive visualizations allow the user to navigate within the 3D space, change the visualization parameters, query objects, and even test design ideas, clearly adding value to the visualization. When these two technologies are combined, a need arises for 3D user interfaces (3D UIs), which provide interactivity within an immersive VE. Throughout our discussion of these technologies, we draw upon our own experience with two interactive VEs for engineering — AMADEUS and Virtual-SAP.

The design and functionality of an optical sensor for distributed measurement of water content in soil is presented. Sensing is based on the characteristics of Brillouin scattering in optical fiber coupled with the characteristics of a hydrophilic polymer used as transducer. The distributed sensing is possible at discrete positions along a single fiber embedded in low permeability media. Experiments with a prototype sensor demonstrated measurement of water-content up to 30% in compacted clay. Swelling and drying of the polymers showed that the water-content measurements are fully reversible.

The permeability of a containment wall is a topic of debate during design and construction. This paper presents the design phase laboratory test results for a quality control program developed to verify that a self hardening cement-clay-slag slurry wall meets the performance criteria in the contract documents. The full QC program includes laboratory testing to evaluate the time-dependent changes of the slurry; bench-scale falling head piezometer tests to check the ability of the method to yield comparable results; a slurry wall test section to compare to the laboratory and bench scale tests; and finally the field implementation during wall construction.

Cone penetrometer (CPT) resistivity and dissipation tests were used to evaluate the liquid levels in waste at a closed landfill. Resistivity results confirmed that the waste is saturated under the free liquid surface. Dissipation results indicated that the waste has no perched liquid layers. The location of the free surface based on resistivity is approximately within two feet (ft) of the levels observed in wells and estimated from dissipation tests. The CPT method was more advantageous than installing leachate observation wells only as the cost of resistivity/dissipation tests was 25% lower and a larger number of measurements were made.

Recent studies of aerobic bioreactors have demonstrated their success in expediting stabilization of municipal solid waste (MSW), reducing or eliminating treatment and disposal costs of leachate, and increasing landfill capacity. Such aerobic decomposition is highly dependent on maintaining optimum distribution of moisture and air throughout the highly heterogeneous waste for the duration of the stabilization process. This requires distributed monitoring of the temperature and moisture in the bioreactor. This work presents the development and implementation of an autonomous monitoring system using an array of wireless sensors (motes). Each mote is equipped with embedded microprocessor, flash memory, and a wireless transceiver. Networked data collection along with 3D interactive visualization tools are developed for efficient assessment of the conditions in the bioreactor.

A comprehensive assessment was performed of the primary and secondary waste compression characteristics of an existing 60-foot deep waste deposit. To obtain in situ waste compression parameters, an instrumented 10.4-acre test fill was constructed, fully instrumented, and monitored over an approximately 6-month long time period. To compliment conventional surface and buried settlement plates, a horizontal settlement profiling system was developed to facilitate settlement evaluations at 1-foot horizontal intervals along four transects at the base of the test fill. This paper focuses on the development of the settlement profiler and provides a discussion of the test results.

Seventeen full-scale test sections were constructed on a low-volume, flexible pavement. The test sections were reinforced with geotextiles and geogrid, instrumented with Micro-Measurement Group foil strain gages. While strain gage attachment to rigid materials is well understood, methods used to attach foil strain gages to geotextiles, specifically, are more challenging due to the matrix of fibers in the material, and the method used to waterproof and protect these gages in a field environment is critical. The survivability of a method used to attach and waterproof the foil strain gages was successfully demonstrated in the field and is described herein.

Contamination in soils and sediment, is very heterogeneous. There are two sources of heterogeneity: fundamental, because of differences in the composition of particles that comprise the population; and distributional, the non-random distribution of particles due to gravity, chemical attractions, human activity, air resistance, etc. Current environmental sampling of soils and sediment utilizes "discrete" sampling". These samples are unrepresentative, highly variable, and unrepeatable. The resulting data is extremely difficult to interpret and legally indefensible. Alternatively, collecting and preparing a multi-incremental sample of perhaps 30 sub-samples over an exposure area provides a single sample that is representative, repeatable, and legally defensible.

A comparison of an existing method and fuzzy modeling to estimate soil-water evaporation from a bare soil is presented. Both methods use input parameters associated with the simplified soil-surface energy balance, as well as easily obtained measurements at remote locations. An optimized fuzzy learning from example (OFLFE) algorithm was developed to generate the fuzzy model. The root mean squared error (RMSE) of the fuzzy model was 35% less than that of the existing method. The results indicate that fuzzy methods can be used to generate evaporation estimation models that predict evaporation better than the existing method.

A pneumatic slug tester utilizing a portable high-speed (up to 200 kHz) data acquisition system was implemented for conducting slug tests in a high permeability sand aquifer (k ∼ 0.001 m/s). Recovery of the displaced water level in such cases often takes only seconds thus requiring high frequency recording of water level changes in order to measure the oscillatory, underdamped response. A data acquisition system was implemented utilizing hardware and software from National Instruments, which allowed for collection of sufficient data to fully measure the aquifer response. The system was also able to record a much higher frequency air pressure oscillation in the well headspace and a waterhammer oscillation in the water column.

Pumping and -field-permeability tests were conducted at four sites to determine soil permeability that is used in designing groundwater control systems. Laboratory tests, on soil samples extracted during site investigation, were performed. Test results were used to check the applicability of the indirect techniques relating permeability to grading characteristics. Confined, unconfined and mixed-aquifer conditions were characterized based on field measurements. It was found that it is more realistic to estimate permeability using field testing. If only data of indirect methods are available, its use sholud be limitted to tender or prelimenary studies. In this case, while implementing some justifications, Hazen's formula can give a good estimate.

In this paper a 2.2mm open-ended coaxial probe is selected for a broadband measurement of material permittivity ranging from kHz up to GHz. The measurement is individually carried out at three different frequency ranges: high frequency (HF, 500MHz – 20GHz), median frequency (MF, 10MHz – 1GHz), and low frequency (LF, 1kHz – 15MHz), in view of pertinent aperture admittance models, feasible measurement principles, and required calibrations for system biases. These considerations are discussed and described in turn from high frequency measurements to low frequency tests. Verification of the associated measurement techniques at the three operating frequency regimes is provided by experiments on pure methanol.

Micro-tunneling and pile driving are two example applications in which the surface roughness of construction materials may be significantly altered during installation. Quantification of this change in surface roughness as a result of large displacement shear-induced wear is a necessary precursor to achieving optimum interface design. This paper describes the results of an initial experimental study that investigated the change in surface roughness of curved interfaces as a result of shear-induced wear. Even for limited shear displacements, results show quantifiable changes in surface roughness and interface strength and demonstrate the importance of considering the shear-induced wear of construction materials.

The rate-dependent behavior of sand is investigated through a series of cyclic triaxial tests. The tests were performed on Monterey 0/30 Sand at loading frequencies of 0.1 and 1.5 Hz over a range of confining pressures, cyclic stresses, and peak stress levels. The frequency of loading did have an effect on the strains measured during the tests under certain conditions. Larger axial strains were measured during the tests performed at the lower frequency for test conditions that resulted in larger axial strains, such as higher peak stress levels and larger cyclic stresses.

This paper presents results of an investigation of the potential to evaluate small stain shear modulus (G_max) anisotropy for unconfined clay samples using a simple test procedure. Vertical and horizontal shear wave velocities (V_vh, V_hv and V_hh) and residual isotropic effective stress were measured on saturated samples of Boston Blue Clay, Australian Burswood Clay, and Norwegian Onsøy Clay using portable piezoceramic bender element equipment and a suction probe. The measured data, which show significant G_max anisotropy for the Boston Blue Clay and Onsøy Clay sites, are evaluated and compared with G_max anisotropy of clays from the literature.

A standard NGI type Direct Simple Shear (DSS) apparatus has been modified to enable the application of unidirectional simple shear monotonic and cyclic loading through an automated electro-mechanical control system. Two algorithms were implemented in a computer control software, one for constant height control during the undrained shearing phase and the other for controlling the horizontal load or horizontal displacement in cyclic stress and strain controlled tests, respectively. It is shown that the adopted automated electro-mechanical control system represents a valid solution for low frequency cyclic tests under constant volume conditions. Typical cyclic test results under both stress and strain-controlled conditions are also presented in connection with the development of laboratory methods for the analysis of seismic pore water pressure build up and liquefaction at level ground.

Signal processing techniques have been introduced in last two decades into geotechnical applications to analyze particle-scale microstructure. In this paper, a different approach for geotechnical application of signal processing techniques will be introduced. The crushing of granular particles was analyzed by using sound analysis technique during the shear process of granular materials. Sound analysis setup is implemented to direct shear box to analyze the crushing of granular materials under shear loading. The microphone signal by using Electret Microphone is processed and the signal coming from microphone was analyzed by using Fourier Transform method. Although the analysis is very complex, it is believed the information obtained will help in understanding when the crushing process begins and the extent of crushing which will lead to better understanding of granular materials subjected to shear.

Economical automated geotechnical testing systems are now available, allowing laboratory tests to accurately represent any given series of loading or unloading conditions from the environment such as slow, rapid, staged, drained, and undrained conditions. High quality path-dependant behaviors may now be investigated with comparative ease. Triaxial stress path tests can now be performed where specimens are subjected to states of stress that closely mimic the in-situ stress states with modest effort and cost. These techniques deserve wider deployment and regular use to significantly improve the quality of soil property assessments and hence geotechnical design.

The undrained cyclic behavior and liquefaction characteristics of sand are highly dependent on the mechanisms observed in static tests. The outcomes of an experimental study on sands carried out to investigate the effects of stress and strain conditions are presented in this paper. In this context, undrained triaxial compression and extension tests were performed on Toyoura sand at different initial relative densities. The outcomes of experiments show that undrained triaxial compression test results differ from the extension test results, especially at high void ratios of sand. Additionally, the results indicated that increasing effective confining pressure results in decreasing dilatant tendencies.

Cemented sand samples were formed and tested using a laboratory-size quasi-static cone penetrometer. The influence of cement content, cement type, relative sand density, and sample cure time on cone penetration resistance were determined. The penetration test data were supplemented by a triaxial test program. The results have shown that the addition of up to one percent cementing agent to sand could have a pronounced effect on cone penetration resistance, and on shear strength parameters. The results also attest to the utility of the static cone as a viable device in assessing relatively small changes in degree of cementation and/or relative density of cemented sands.

This paper presents the spatial variation of electric cone tip resistance measurements. Excerpts from an extensive site characterization are presented to provide the necessary background information. This paper deals with the field data collection of electric cone tip resistances as the sensing method and devices that utilize spatial models. The emphasis of the paper is to show spatial features of these measurements made in wet and dry weather site conditions through the use of color contour maps. The contour map display confirms the effect that an unsaturated soils condition has on site characterization.

Cone Penetration Testing (CPT) is a flexible and cost effectiveness in situ characterization technique, able to determine a wide array of subsurface properties and conditions with fine spatial resolution. However, refusal of the probe at shallower than desired depths has remained a limitation in difficult geologies. The Enhanced Access Penetrometer System (EAPS) combines CPT sounding with small-diameter, air rotary drilling to cut through refusal layers. The ability to alternate between penetration modes maximize the data obtained. An integral larger drill and an innovative spoils containment and sampling system which provide additional benefits are also described.

A modified portable drilling and sampling technique called "flow through" sampler is developed during the last twenty-two years of field work. This technique is specially suited to perform subsurface investigation in remote and inaccessible areas where the standard drilling and sampling techniques are very expensive as well as time consuming. The technique relies upon a hydraulically operated jackhammer and a "flow through" sampler which allows soils to flow inside out as required. Case histories with a wide range of unfrozen to frozen (warm temperature) soil conditions are presented in this paper to illustrate this unique, cost effective subsurface investigation technique.

Application of Cone Penetration Test (CPT) data for geotechnical analysis and design has shown an increase in recent years. A main purpose of the CPT is to identify soil layers boundaries and determine pile capacity from the measured values of cone resistance, sleeve friction, and pore pressure by piezocone (CPTu). A computer program called "UniCone" has been developed for processing results of CPT and CPTu, soil profiling and pile capacity analysis with different methods. Among different worked examples within "UniCone", a few cases has been reviewed for practicing engineers, and comparison of current methods for soil profiling and pile capacity estimation.

A new in situ testing device has been developed, the Multi Piezo Friction Attachment (MPFA), to allow for the direct characterization of geotechnical interface behavior in situ within the context of an effective stress framework. The MPFA simultaneously provides four independent measures of interface response (f_a1, f_a2, f_a3, and f_a4) and five independent measures of dynamic pore pressure along the shaft (u_a0, u_a1, u_a2, u_a3, and u_a4) in addition to conventional cone penetrometer measurements (q_t, f_s, and u₂). This paper summarizes the rational behind the development of an in situ test device to directly characterize interface strength in situ while accounting for the influence of penetration and shear induced pore pressures and varying the geomaterial counterface roughness. An overview of the device specifications is presented along with selected results from field tests demonstrating the capabilities of the MPFA device across a broad range of in situ testing applications.

In this study, distributed sensing based on Brillouin scattering is used to measure high-resolution dynamic strains on structural components. First, single point measurements were taken over a steel beam subjected to damped-harmonic oscillations. The strain measurements were recorded every 10 ms with maximum of approximately 500 microstrains, and accuracy of 0.01%. The average frequency of oscillation was determined 4.2 Hz, which was fairly close to the theoretical natural frequency of the beam (4 Hz). Second, distributed measurements of hoop strains were taken on a concrete column section subjected to axial compression. The fiber was wrapped around a 15 cm diameter and 30 cm long section, over multiple layers. The measured strains were compared to analytically predicted and independently measured strains along the height of the column.

In order to evaluate the applicability of an optical-fiber sensor system in the instrumentation of piles, laboratory and field tests were conducted. A multiplexed sensor system, constructed by arranging several Fiber-Bragg-Grating (FBG) sensors along a single optical fiber line, is capable of measuring local axial strains as a function of wavelength shifts. From the strains measured by FBG sensors, the distributions of axial load in three model piles and a field test pile are found to be comparable, in terms of both magnitude and trend, to those obtained from conventional strain gauges. The result of an application suggests that the FBG sensor system is an effective tool for the analysis of the axial load transfer in piles.

This paper describes the use of fibre optic sensing with Brillouin Optical Time-Domain Reflectometry (BOTDR) for near-continuous (distributed) strain monitoring of a large diameter pipeline, buried in predominantly granular material, subjected to a pipe jack tunnelling operation in London Clay. The pipeline, buried at shallow depth, comprises 4.6 m long sections connected with standard bell and spigot type joints, which connect to a continuous steel pipeline. In this paper the suitability of fibre optic sensing with BOTDR for monitoring pipeline behaviour is illustrated. The ability of the fibre optic sensor to detect local strain changes at joints and the subsequent impact on the overall strain profile is shown. The BOTDR strain profile was also used to infer pipe settlement through a process of double-integration and was compared to pipe settlement measurements. The close approximation of the measured pipe settlement provides further confidence in fibre optic strain sensing with BOTDR to investigate the intricacies of pipeline behaviour, pipe-soil interaction and interaction between pipe sections when subjected to ground movement.

This study developed three types of monitoring systems, the BOTDR (Brillouin Optical Time Domain Reflectometer) system, the FBG (Fiber Bragg Grating) system and the MDM (Macro Distortion Monitor) system, to monitor road slope failures using optical fiber sensors. These systems have been tested at several sites in Japan to check their applicability. This paper reports the result.

The Highways Agency (HA) in the United Kingdom is responsible for managing the 7,088 km motorway and trunk road network in England. As part of the development of a `pro-active' asset management strategy to improve the safety and reliability of the roads network, the HA are developing the use of airborne remote sensing techniques to assist in prioritising their detailed ground based inspections of earthworks. This paper will describe one particular area of progress, namely the use of sets of LiDAR survey data to identify `change' in slope profile both qualitatively and quantitatively as a measure of slope condition.

Personal Digital Assistants (PDAs), which belong to a class of mobile computers, is an important IT product. Currently, the most common use of PDAs is for personal information management. The high portability, low cost, and expansion capability of PDAs make them attractive for field instrumentation. This paper describes an example where a PDA is used to replace a laptop computer in the Time Domain Reflectometry (TDR) measurement system. The operation is significantly improved by use of a PDA. The performance can be further improved by incorporation of other information technologies such as wireless communication, global positioning systems, etc. While the paper uses TDR as an example, the technological aspects have general implications.

Miniaturized, wireless instrumentation is now a reality and this paper describes development of such a system to monitor crack response. Measurement of micro-inch crack width changes in residential structures can now be employed to supplement control of construction vibrations through comparison of environmental (long-term) and blast-induced (dynamic) response. A low power consumption potentiometer displacement transducer and a short communication duty cycle allow this system to operate wirelessly up to a year with AA size batteries. The system described won third place honors in the 2005 Crossbow Smart Dust Challenge, which represented the best executable ideas for wireless sensor networks.

The urban underground environment is under continuous development as the infrastructure ages and new technologies are added to the existing networks. Design, construction, installation, and repair in this ever-changing environment can benefit significantly from high-resolution imaging to acquire adequate subsurface characterization. This paper documents the development of MEMS accelerometers as a low-cost alternative sensor to geophones and piezocrystal accelerometers for monitoring wave propagation in soils. The experimental study includes an evaluation of limitations and the development of a simple packaging system for the broad application of MEMS in the geoenvironment. The calibrated accelerometers are used to monitor elastic wave propagation for the evaluation of changes in the effective state of stress within a 1g model of a braced excavation. The experimental program captures the effects of load and deformation as elastic waves propagate behind a sheet-pile system. Results hint at the development of long-term non-destructive monitoring systems for the diagnostics and control of geotechnical processes.

Trials sponsored by the UK Highways Agency and the British National Space Centre are underway to investigate the potential for using satellite interferometric radar techniques to monitor ground displacements along the highway network. The current phase comprises the evaluation of the CATInSAR technique which it is reported can detect displacements down to millimetric scale. This paper provides a summary of satellite radar sensing and processing techniques, describes the background to the CATInSAR trials and presents the data currently available. Full results of the trial will be available to present at the conference.

Time Domain Reflectometry (TDR) has been utilized to monitor slope movement in a variety of geotechnical settings including highway cuts, rail beds, and open pit mines. Until now, the interpretation of TDR results for detecting slope movement and identifying the location of shear planes has been limited to visual inspection of the plots of cable reflectance versus distance along the cable. We describe novel signal processing techniques that extract reliable indications of slope movement from the TDR data and present a comparison to both slope inclinometer results and visual interpretation of TDR. In this comparison, the more advanced signal processing yielded reliable indications of slope movement well earlier than both visually interpreted TDR and slope inclinometer results.

The nonlinear vibrations of dynamic soil compactors are taken as the basis for feedback control systems for intelligent compaction. According to the achieved compaction, the parameters of the soil compactor are continuously changed. The vibratory roller measures the stiffness of the subgrade. In conjunction with GPS-data, this measurement can be used as a QA/QC tool. The stiffness data are directly correlated to plate bearing test. In practice, the intelligent compaction ensures that the compaction job is completed in a minimum number of passes, the result is monitored and the compaction energy is automatically adjusted while measuring the soil stiffness.

For compaction control, dry density and water content are the current parameters. However, there is a trend towards using the modulus as a compaction control parameter instead of dry density. The Briaud Compaction Device (BCD) is a new instrument to obtain a soil modulus in only a few seconds. The article describes some numerical simulations which were performed to validate the new instrument.

Time Domain Reflectometry (TDR) is now being used to determine both water content and dry density of soil. A Two-Step Method (ASTM D6780-02) was complemented with a One-Step Method (ASTM D6780-05). The latter makes use of measured apparent dielectric constant and electrical conductivity and six calibration constants obtained from laboratory compaction tests. This relatively new procedure continues to be refined as research and experience provide more insight and data. This paper presents field calibration procedures to refine the calibration constants using independent field measurements. The procedures are illustrated with recent field testing data.

Controlled test sections were constructed using a prototype CP-533 vibratory padfoot roller to evaluate relationships between machine drive power and measures of soil compaction. Machine power determined from internal sensors and number of roller passes was logged nearly continuously during construction of the test sections using an onboard computer and GPS mapping system. In this paper, machine power results are compared to spot measurements of nuclear density gauge moisture/density and dynamic cone penetration (DCP) index measurements. A framework for statistically analyzing power-based compaction monitoring data is presented with broader implications for other intelligent compaction and continuous compaction control systems that generate near continuous spatial data.

The structural design of highways is based on engineering parameters, such as strength or stiffness. Unfortunately, construction specifications are not based on these properties. Unfortunately, acceptance criteria are typically based on adequate thickness or density of the placed materials. A procedure to measure the modulus of each pavement layer after placement with seismic technology is presented. Field and laboratory tests are incorporated so their results can be reconciled without any scaling or simplifying assumptions. In this paper, the overall method and procedures to establish the accuracy and repeatability of the methods are described and a case studied is also included.

This paper presents roller vibration data captured during compaction of a heterogeneous test bed. When operated near the sensitive resonance frequency, drum vibration amplitudes and phase vary considerably geometrically within a single pass and to the same order of magnitude as that observed when the soil undergoes considerable compaction and stiffening.

The mechanical behavior of granular soils is highly dependent on the particle microstructure, which includes the shape, distribution, and arrangement of particles and void space. Because of the inherent difficulties in measuring soil properties on a microscale, geotechnical engineers use macro properties to estimate the response of soil when subjected to changes in the state of stress. These macro properties (void ratio, porosity, density, uniformity, etc.) are used to represent gross or average measures of the soil microstructure in terms of engineering behavior; i.e., strength, compressibility, and permeability. Non-destructive systematic test methods are described for quantifying microscale measurements of scanned digital images using x-ray computer-aided tomography (CT). Tomographic analyses conducted on five different soils indicate that x-ray CT technology provides a viable means for nondestructively observing and measuring grain size distribution, pore characteristics, and pore size distributions of soils.

Lightweight treated soil mixed with air foam has been proposed for application in waterfront construction. The permeability of the material is an important characteristic governing changes in its mechanical properties and the possibility of ground water pollution. In this paper, permeability tests were conducted and the permeability mechanism was observed using a micro-focus X-ray CT scanner. We concluded that the permeability of lightweight treated soil mixed with air foam is governed by the permeability of the mixture of clay and cement, the presence of impermeable air, and the possibility that channels facilitating water flow may form in the LWS.

A new permeation test system was developed in order to visualize the water permeation phenomena in rock by X-ray CT. The characteristic point of the developed system is that permeation tests under the high inlet pressure tests (up to 20 MPa) become possible using industrial X-ray CT scanner. In this study, one dimensional tracer tests were carried out, and the flow velocity and permeability of the rock were evaluated from the X-ray CT image data. The evaluated permeability was consistent with the result from transient pulse method, and the effectiveness of the developed system was verified.

A tunnel face failure is simulated by pulling out a tunnel model set in a model ground. The ground is then investigated by X-ray computed tomography (CT) scanner in order to not only visualize the failure zone in three-dimensions but also evaluate mechanism of the face failure quantitatively. Based on the resulted failure mechanism, the stability analysis is conducted using limit equilibrium method. Finally, it is confirmed that X-ray CT is a useful tool even in geotechnical engineering fields, especially of solving boundary value problems.

Crack aperture distribution in rock induced by splitting is estimated by the X-ray CT method. This is a promising method that measures the crack aperture from X-ray CT images. The fundamental formulae for crack aperture measurement were described first as well as the necessary noise reduction and the data processing techniques. It was found that crack aperture distribution was accurately evaluated. It was also shown that this newly developed nondestructive method by X-ray CT is effective for estimating crack aperture in rock.

The purpose of this paper is to investigate three dimensional (3-D) failure patterns in sand due to laterally loaded pile using industrial X-ray CT scanner. First of all, a model test apparatus is developed with an automatic loading system at pile head. Then, pile loading test is performed with increasing load levels. CT scanning is conducted for model ground at several loading steps. Not only cross sectional images of the failure patterns but also 3-D ones are reproduced. Finally, 3-D lateral bearing capacity mechanism of pile foundation is visualized and discussed quantitatively.

Providing adequate drainage layers underneath pavement surface course has been recognized as one of the most important design considerations. In Ohio, several different types of permeable base materials, including both bounded and unbounded open graded aggregates, have been used. However, there is no documented study on the comparative drainage efficiency of these base materials under field in-service conditions. This paper presents instrumentation and monitoring project aimed at measuring moisture variations over time in pavement sub-layers. Representative field measured moisture data for three sections are presented. A statistical analysis of COV of moisture content at different base sections reveals that ODOT 306 cement treated base performed the best.

The ultimate nondestructive testing (NDT) tool for the evaluation of all pavement systems would be a device that integrates different test methods. The first step toward a fully integrated hardware is a robust integration software. The objective of this software is to harvest the strength of different NDT methods and combine them in a way as to improve the parameters used in pavement design and evaluation. Integrating the data from different methods falls under the two broad categories of joint inversion, and data fusion. The implementation of these two methods is described in this paper.

The mechanical properties of asphalt pavements vary significantly under the application of loads at different speeds. Several tests, both static and dynamic, have been carried out at the IGT/ETHZ circular test track. The testing device is equipped with sensors (strain gauges, vertical deflectometers, and temperature sensors) which measured the horizontal, the vertical strains and the temperature at different depths. The results show a rate and time dependency, which becomes more relevant at increased temperatures. The climatic conditions and the temperature have been monitored and collected continuously during the tests. Static load tests (Benkelman beams) were also conducted. A three dimensional back calculation analysis was performed using the finite element code ABAQUS in order to obtain the stiffness parameters under static and dynamic load. ABAQUS built-in material models were shown to reliably predict the dynamic and static mechanical behavior of asphalt pavements.

New Jersey Department of Transportation (NJDOT) initiated a study with the objective to calibrate AASHTO seasonal and temperature adjustment models, or to develop new ones that will take into consideration New Jersey specific environmental conditions. To achieve the objective, twenty-four pavement sections were instrumented to monitor environmental parameters and a nondestructive testing (NDT) program was conducted for a period of two years using Seismic Pavement Analyzer (SPA) and Falling Weight Deflectometer (FWD). Based on collected data, temperature and seasonal models are being developed by performing statistical analyses. This paper concentrates on pavement evaluation and model development based on SPA results.

This paper presents the methodology and application of an interactive GIS map-based decision support program developed for Georgia Department of Transportation's multiyear pavement needs analysis system. The program integrates GIS capabilities, including visualization, identification, and spatial analysis, with multiyear pavement performance forecasting, treatment determination, and pavement preservation needs analysis. It allows engineers not only to visualize spatial and temporal pavement needs analysis results on a GIS map, but also to perform various what-if scenario analyses directly on the GIS maps. Thus, engineers can easily incorporate additional data and make effective decisions. A case study using the actual historical pavement condition data surveyed by the Georgia Department of Transportation is presented to illustrate the capabilities of the developed program.

This paper describes a Windows-based application (WiscLEACH) for assessing ground water impacts associated, with leaching of metals from fly-ash stabilized soil layers used in roadway construction. Release of metals from the fly-ash stabilized soil is assumed to be sorption controlled. The application is based on two analytical solutions for solute transport and was calibrated using a two-dimensional finite element model for flow and transport in variably saturated media. Parametric studies indicate that maximum concentrations in ground water are most sensitive to depth to the ground water table, thickness and width of the stabilized layer, hydraulic conductivity of the stabilized layer and the aquifer, and the initial concentration in the stabilized layer.

The objective of this paper is to evaluate the crack resistance of asphalt pavement using geosynthetics reinforcement materials between the surface and the base layer of asphalt pavement. The specimens of geosynthetic-reinfprced asphalt mixtures, which include the two kinds of asphalt and geosynthetics were respectively prepared for testing and evaluation. The three point static bending beam test was carried out at –10 degrees C, and the three point fatigue bending beam test, bending fracture test in the reflection crack test, and shear fracture test were carried out at 5 degrees C, 20 degrees C, and 25 degrees C, respectively. The results show that geosynthetics reinforcement increased the crack resistance of the asphalt pavement system, and that the modified asphalt exhibited increased reinforcement.

Repeated load triaxial tests to 10⁵ load repetitions, performed on laboratory-compacted uniform dry sand from the Arab Gulf Region, have shown that permanent axial strains are largely governed by the magnitude of the repeated deviator stress. At stress levels below about 65% of ultimate samples' strength, a relationship based on the power law model (ε^p = AN^b) of permanent strain versus load repetitions (N) was arrived at. Additionally, resilient (recoverable) strains, occurring simultaneously with permanent strains, increase with the magnitude of the repeated stress. This type of material characterization, when coupled with layered elastic methods, could predict permanent deformations in sand subgrades under traffic loads.

This paper uses the Empirical Mode Decomposition (EMD) to analyze the road surface profile of two flexible pavements in varying conditions. It is also used in the fundamental derivation of roughness. EMD is part of a larger method known as the Hilbert-Huang Transform (HHT). Previous studies have indicated that road profiles are inherently non-Gaussian and non-stationary; this makes the EMD a very appropriate method. The central idea of HHT is the EMD, which is then decomposed into a set of intrinsic mode functions (IMF). The Hilbert transforms can then be applied to the IMF. The EMD appears to be more appropriate than other methods that have been used. A simple example of two pavement profiles with different degrees of "profile" was analyzed and the EMD was used for both quantitative and qualitative identification of the type of profile.

This paper discusses the design of an impact test system for rapid evaluation of pavement subgrade. The system delivers similar amount of energy into the ground. Experiments at several locations indicates that the impact characteristics such as peak acceleration and impact duration of the falling plate is highly correlated to shear wave velocity of soils at the ground surface. This observation is further validated by results of numerical simulation. In addition, it is found that the characteristics of the acceleration process during impaction process contains information of ground profiling such as the existence of underlying layer and the thickness of the surface layer. A sensitivity study is conducted to optimize the impact measurement system design. The system can be used for evaluation of pavement subgrade and for other shallow foundation applications.

During pile driving, static and dynamic soil forces resist pile penetration. Certain soils exhibit significant elastic behavior, causing unfavorable high-rebound which adversely affects pile driveability and complicates its bearing capacity assessment. This paper discusses the types of piles and soil conditions where the negative effects of high-rebound on the performance of the hammer system, pile, and soil have been observed, and a case history where field instrumentation and testing were performed. The case history involved the driving and testing of a 762 mm square, 35 m long, prestressed concrete pile driven into saturated fine silty to clayey sands and sandy clays that exhibited high pile rebound. Dynamic pile measurements were obtained during initial pile installation and restrikes to assess pile driveability and bearing capacity. Full-scale static load testing was performed to measure static pile bearing capacity and pile load-movement. A correlation between the static load test and dynamic test results is presented.

Modern methods for designing drilled shafts, ACIP piles and similar foundations in soft rock require knowledge of the compressive strength and modulus of the rock. However, jointing at many sites prohibits the recovery of samples of sufficient length and integrity to test rock cores in either unconfined or triaxial compression. Since rational design procedures usually require values of compressive strength, surrogate methods must be employed to estimate the compressive strength of the rock. The surrogate methods considered here is the Texas cone penetrometer test (in which a 76-mm-diameter solid steel cone is driven into rock at the bottom of a borehole in much the same way as a split spoon is driven during the performance of a standard penetration test in cohesionless soil). An other issue during deep foundation construction is essential to locate the a rock stratum, especially when drilling with slurry, in which the bottom of the borehole cannot be observed and the cuttings may be so disturbed that overburden soil cuttings cannot be easily distinguished from cuttings in soft rock. Hence, a new static rock penetrometer was developed based on the concept of the "pocket penetrometer," which has been used by field geotechnical boring loggers for many years. Soft rock formations typical of those for which such substitutions might be used are the upper Cretaceous formations of North central Texas, including the clay shale and limestone formations. The correlations between compressive strength and the Texas cone penetrometer test are formation-dependent, most likely through the degree of cementation present in the geomaterial. Also, the performance of the static penetrometer was verified in the field in boreholes that were drilled at the test sites in North central Texas. The readings at these sites, together with the values of q_u measured using cores taken from the same elevation as the penetrometer test and Texas cone penetrometer resistance values at the same elevation in nearby boreholes. The readings were all made in open boreholes, not under slurry. Based on test results, a static rock penetrometer reading between score marks B and C ("B-C") is indicative of soft, sound clay shale, and a reading of C or higher is indicative of sound limestone or sound, hard clay shale. Readings of B, A-B and A are indicative of overburden materials.

Inclinometer devices are commonly used to monitor changes in displacement at numerous points along the length of a borehole casing or structural element. A common method to determine deflection profiles is to perform a survey using a retrievable probe consisting of one bi-axial tilt measuring device. This paper describes an in-place inclinometer system that links together a network of digital bi-axial accelerometer sensors that communicates readings over a single cable. The in-place inclinometer system is contained in a single continuous housing suitable for direct burial, attachment to structural members, or embedment in concrete, grout, or epoxy. This system differs significantly from the retrievable probe inclinometer approach because it does not use alignment wheel assemblies and special casing with internal grooves. Further, the in-place inclinometer system provides instantaneous profile measurements for real-time monitoring and can be used to capture low-g acceleration parameters or time histories for applications involving vibrations, earthquake ground motions, or impact loading events. Remote monitoring can be accomplished where displacement profiles are obtained on a regular basis without the need for time consuming and expensive field visits.

The behavior of laterally loaded step tapered bored piles in calcareous sand was examined by field tests. Tests were carried out on straight and step tapered bored piles 5.3 m long embedded 5 m below ground level. All tests were carried out to failure to examine the ultimate lateral capacity, and the deflection at working loads. Test results indicate non linear response and substantial increase in lateral capacity and decrease of deflections at working loads for the step tapered piles compared with the straight shaft piles.

Automated data acquisition systems are now available for a variety of deep foundation systems including cast-in-place piles. While enhancing the quality of data obtained during the pile casting process, these systems significantly increase the type and amount of data recorded with regard to auger penetration. This paper presents the full details of a data acquisition, management and presentation system for drilled displacement piles currently in use in North America. Details include recorded parameters, recording methods, field data storage and presentation and permanent data storage and presentation systems. Implications of the availability of this data are presented in the companion paper, "Application of Acquired Drilled Displacement Pile Installation Data".

The planned LNG terminal is a regasification facility that includes three (3) double-wall storage tanks for a daily send-out capacity of 1.2 billion cubic feet (33 million cubic meters). The project site features thick soft varved clayey silts. Characterization of this layer, especially its shear strength, permeability, and preconsolidation history, is critical to the foundation design and construction. This paper compares different methods used to characterize the varved clayey silts. Site specific coefficients were generated for the pile capacity analysis and settlement prediction. Recommendations were made for the foundation design and construction based on the characteristics of the varved clayey silts.

This paper presents the summary of a series of pressuremeter test results that were obtained from one particular area. As part of investigation for a bridge foundation the tests were performed over a few locations along a river. The background and objectives of the study are presented. The test details are also given. Parameters determined from the tests predict the lateral resistance behavior of the soil. The results are compared with those from previous tests in the same area. They were also used to establish a correlation with standard penetration resistance.

With new development, and increasingly more redevelopment, within urban areas, there is a clear need to efficiently and safely develop underground space. A major concern when placing deep excavations in urban environments is the impact of construction-related ground movements on adjacent buildings and utilities. In practice, when designers are faced with an excavation where ground movements are a critical issue, they can estimate movements using semi-empirical methods or results of numerical modeling. It is common to include a monitoring program during construction to record the ground movements and, in some cases, adjacent building movements. Ideally, these observations would be used to control the construction process and update predictions of movements. This paper describes novel developments in the user of laser scanning and digital photogrammetry for developing an accurate record of construction activities. These new technologies are illustrated using excavations in the Chicago area.

A deep excavation immediately adjacent to the Virginia State Capitol building required monitoring the building during construction. A real-time instrumentation system was installed, consisting of three theodolites with about 80 optical prisms, two in-place and one manual inclinometers, temperature sensors, and the necessary data acquisition hardware, software, computers, and Internet connection. The system proved to be an effective means of monitoring movements as well as helping to control the various phases of the construction. The alarm signals issued by the system proved very useful, resulting in close coordination of construction activities among the team and preventing movements from exceeding the desired tolerances.

In the past few decades, the pre-stressed anchor system has been extensively used to increase the stability of slope among the Taiwan Island. Several disasters have occurred that caused by the sudden failure of pre-stressed anchor system. This article presents a real-time acoustic monitoring system that provides the field real-time condition assessment. A demonstration project was made by using field-loading test on two pre-stressed anchors with the real-time acoustic monitoring system. This article discussed the acoustic features of the concrete cracking, wire breaking, and anchor rupture. A strategy of the early warning system is proposed for the pre-stressed anchor system.

This paper presents the results of a comparative study on the design approaches for geosynthetic reinforced modular block walls in a tiered configuration. Stability calculations were made on a number of field wall designs using the currently available design approaches and the discrepancies in the results were identified. Also conducted was a series of finite element analysis using a calibrated finite element model on design cases having various offset distances, aiming at identifying qualitative and quantitative discrepancies between the results from the limit equilibrium-based calculation models and the finite element model. The results indicated among other things that the current design approaches yield significantly different results in terms of reinforcement loads, and that the calculation models adopted in the current design approaches tend to yield significantly larger reinforcement loads in bottom layers in lower tier when compared to those computed by the finite element model. Practical implications of the findings obtained from this study are highlighted.

Deep mixing methods can be used economically for the construction of cut-off or excavation support walls where other systems such as traditional soldier beams and lagging walls would yield unsatisfactory performance, where the installation of vibrated or driven sheet piles could cause vibration induced settlements and where concrete diaphragm walls would be time consuming and expensive. The new CSM method can largely replace the more conventional single or multiple auger methods of soil mixing or jet grouting. The cutter tool is similar to a cutter used in diaphragm walls or cut-off walls and is operated with a Kelly mounted on a drill rig. With this system much deeper walls can be installed and even hard soil layers can be penetrated.

This paper summarizes developments to predict, monitor and control deformations due to excavations. The developments are integrated to provide engineers and contractors with a system that allows real time performance data acquisition, evaluation and prediction of responses associated with supported excavations in urban areas. The paper summarizes developments in laser scanning and webcams to accurately track excavation progress and other construction activities, automated and remote instrumentation to measure ground and structural responses, intelligent numerical models to learn from field observations and subsequently predict anticipated ground responses and integration of these heterogeneous data using a GIS based system. These new developments and technologies are illustrated by examples culled from recent excavations through soft clays in the Chicago area.

The reliability of a cantilever retaining wall is analyzed, for static stability conditions, as a series system with correlated failure modes. Modal correlations are analyzed. Computations performed using Monte Carlo simulations for a case example indicate the modal correlations are positive and first-order upper bound reliability approximations are applicable.

Design and construction of temporary shoring systems often seems straightforward. Unfortunately, the methods of construction and unknown conditions of the ground make every project unique. A case history of temporary shoring installed adjacent to a historic structure in Washington, D.C. included a complex system of underpinning and excavation support. The Owner requested monitoring throughout construction. Traditional manual measurements provided inconclusive results and created significant discomfort with the performance of the system. Therefore, an automated monitoring system was installed, which provided reliable data confirming system performance and allowed the engineers and owner to separate true ground movement from normal data scatter.

Although three-dimensional laser (3DLS) scanning has been used to document and monitor individual excavation walls and structures on a limited basis, impediments remain to its use for major infrastructure projects. This paper outlines current technological opportunities and obstacles for using 3DLS to predict excavation-induced, damage prediction. Specifics are provided as to limitations regarding cost, optical resolution, processing time, data set convergence, data conversion, and data mining. Specific solutions are proposed to advance the state-of-the-art.

The commonly existing methods of evaluating stress distribution in soils rely on the use of buried or surface mounted load cells. These measurements are difficult to perform and are limited in their ability to capture the stress variation. A relatively new technology, which makes use of flexible, grid-based, tactile pressure sensors, allows to measure stresses at a large number of points in proximity to one another, hence providing a realistic normal stress distribution. Their thin (0.1mm) flexible film overcomes the effect of stiffness variation introduced by rigid load cells and thus allows for measurements that better represent the existing stress conditions. The application of the tactile pressure technology to soils requires adaptation and calibration due to its innovative principle of operation. Examples of work carried out over the past ten years are provided. The presented research addresses three subjects in soil mechanics: (i) the effect of grain size on stress distribution measurement along a boundary with a solid surface, (ii) the pressure dip under the sand heap, and (iii) the contact stresses under a rigid strip footing.

The submission presents the methodologies and conclusions of an experimental study aimed at estimating the "stresses" which develop on a buried structure as it interacts with the surrounding soil under load. The study has been based on measurements made on model structures tested in a pressure chamber. The model buried structure, was a very rigid right cylinder designed such that it could be fitted with roofs of different thicknesses. The structure bottom and roof were instrumented with newly designed and constructed pressure cells based on the null response concept. The development of pressure on the structure was measured as load was applied to the soil surface. The results illustrate the effect of roof stiffness on the development of pressure at the roof center. The stiffer the roof the greater the pressure, however the development of pressure is also seen to be dependant upon the actual deflection. In the case of a flexible roof it is seen that the development of pressure is a non-linear function of the pressure applied at the soil surface and is highly dependant upon stress load unload history. In sharp contrast, it is seen that pressure on the stiff roof develops as linear function of pressure applied at the soil surface and is independent of load unload history.

This paper presents field measurements of the shaft shear stress and the horizontal stress made during the installation of a 73mm diameter instrumented pile in a heavily over-consolidated dense sand deposit. The measurements are compared with Cone Penetration Test (CPT) measurements to investigate the causes of friction fatigue on displacement piles in sand.

The interaction forces and applied stresses at the interface between granular soils and solid boundaries develop the subgrade reaction; a critical component of a structural or systems response. Historically, relatively intrusive measurement devices, such as pneumatic and diaphragm stress cells, have been utilized for soil-structure interface force and stress measurement. Due to the imposed discontinuity at the soil-solid interface, significant distortion of the stress field is likely to rotate the stress distribution and, furthermore, phenomenon such as reinforcement cause by mismatched soil and cell stiffness and arching result in erroneous measurements. The development of resistive-ink based thin-film tactile force sensors offers the opportunity to measure interaction force at soil-solid interfaces using a minimally intrusive design, which may alleviate the errors produced by the physical disruption of the stress field. This paper presents some preliminary results of an ongoing experimental program that utilizes an array of commercially available tactile sensors to measure the development of soil contact force on a complex solid boundary during dynamic soil placement and densification.

CH2M HILL completed a seismic vulnerability study of the historic Hyperion/Glendale Viaduct (bridge) located near downtown Los Angeles. As part of the study, CH2M HILL applied innovative computer modeling and numerical techniques to the stiffness of the existing pile foundations. Analyses of the pile foundations indicate pile failure during the maximum credible earthquake (MCE) event. Stiffness results generated by the computer modeling agreed well with validation results. The computer modeling and finite element analyses of all of the very large pile group/cap systems saved significant calculation time compared to generally accepted hand-calculation methods.

Realistic numerical modelling could transform the way geotechnical engineers design underground structures. This paper will attempt to address the complex soil-structure interaction problems commonly faced by geotechnical engineers and the application of numerical modelling in solving such problems. Special emphasis will be given to 3D numerical modelling associated with ground movement/damage assessment and the design of raft foundations, tunnel and underground construction involving complex excavation sequence.

Ballasted rail track substructure usually consists of graded layers of granular media of ballast and subballast (capping) placed above a compacted subgrade (formation soil). The optimum design of railway track substructure relies on many factors that affect the performance of the track. In this paper, the response of railway track to various factors affecting track performance is investigated by carrying out a parametric study using the finite element analysis (PLAXIS). A plane strain finite element model of railway track section is developed and used for the parametric study. The feasibility of the developed finite element model is examined by comparing its results with measured field test data. The various track factors investigated include the thickness and stiffness of different track layers, shoulder width, and track modulus. The results demonstrate that the subgrade stiffness seems to be the most significant factor affecting track response, thus, the numerical model and experimental data are used to investigate the capability of different stabilization techniques, such as geosynthetics and grout columns, for improving track subgrade behavior.

The development of more powerful computers, sophisticated computer models, and analytical programs with easy to use graphic interfaces provides the designer with powerful tools for modeling and evaluating soil structure interaction. However, the complexity of available computer models, and the enormous amounts of data generated by the modeling programs, can make the results of these programs difficult to verify. This paper discusses the selection of soil properties and boundary conditions for staged excavation models. Methods to check the output using such things as simple hand calculations and duplicate models are discussed. A case history is used to illustrate the methods.

This paper presents the technical approach and the results of site response and seismic soil-structure interaction (SSI) analyses performed to develop free-field and SSI racking deformation that the reinforced concrete box structure subway will experience during the design seismic event. The study compared results computed from different computer programs (SHAKE, FLUSH, and FLAC) using equivalent linear and nonlinear soil models. In addition, the effects of soil stratigraphy and the construction methods are evaluated and presented in this paper. Results of the analyses were compiled as racking curves to be used for final design of the reinforced concrete box structure.

The vertical load-displacement-capacity response of footings is numerically evaluated in FLAC simulations using embedded stress-strain-strength curves that range from the small-strain shear modulus (G_max) to the shear strength (τ_max). As strains and loads increase, the modulus is reduced accordingly using a logarithmic function with physically-based parameters, including a reference strain (γ_r = τ_max /G_max) and strain at failure (γ_f). The ratio of these two strains (χ_L = γ_f/γ_r) defines the degree of nonlinearity of the stiffness reduction. An approximate closed-form expression is derived and applied to a case study footing load test.

A 150m x 67m by 2.75m thick mat foundation was found feasible for supporting a Digester Complex at a wastewater treatment plant in New York City. Heavy ring wall loads resulted from the ten tanks which had individual capacities of 11.4 million liters. The paper demonstrates the important role played by numerical modeling in performing a rational design of a mat foundation and also in evaluating its deformation pattern during initial filling of tanks after construction. For the loading, geometry, soil and boundary conditions, numerical modeling captured an unusual pattern of mat deformation and accompanying bending moments and shear forces which would have been difficult to do without it. Numerical modeling was also crucial in understanding the mat deformation pattern resulting from test filling of two Digesters which would have been difficult and onerous to evaluate without the model.

In this study, the measurement of the P-wave velocity in granite was conducted under controlled temperature and humidity. Lead-zirconate-titanate (PZT) ceramics were used for sensors that were attached directly on the surface of the rock specimen of 60 mm cube. It was found that P-wave propagation properties were affected by the environmental conditions. The relative humidity had the strong effect on the P-wave velocity. When the temperature was higher than 55 degree centigrade and the relative humidity increased, the P-wave velocity decreased due to the crack growth by stress corrosion. It can be concluded that subcritical crack growth caused by stress corrosion occurs for microcracks due to the thermal stress and the water vapor.

A remotely-operated underwater impact device for shear wave velocity (V_S) profiling of near-surface sediments (0.3 to 7 m depth) using Scholte-type interface waves was developed and tested. The effectiveness of the device was demonstrated through terrestrial tests comparing the performance of the remote source to a conventional impact hammer source. Data were collected and analyzed using the Spectral-Analysis of Surface Waves (SASW) methodology. Underwater measurements were conducted with the remote source and both contacting and non-contacting instrumentation. The results from these studies demonstrate the effectiveness of this system for generating Scholte wave dispersion data for near-surface profiling applications underwater.

A large portion of Brazil is covered with tropical soils but literature about dynamic parameters of these soils is very limited. SCPT and cross-hole tests were carried out at an experimental research site inland in the state of São Paulo, Brazil. Shear wave velocities (V_S) determined based on both tests are presented and compared. A good agreement was observed between both test results and the differences can be associated with soil variability, which was very sensitive to CPT tests. It was also observed that Go/q_c ratio determined based on SCPT appears to be an interesting technique to help identify tropical soils.

Three widely-available surface wave measurement techniques, including two active-source methods, the Spectral Analysis of Surface Waves (SASW) method and the Multi-channel Analysis of Surface Waves (MASW) method, and one passive-source method, the Refraction Microtremor (ReMi) method, were applied at a complex-layered site. Dispersion relations were compared to one another. Outcomes from the MASW measurement reveal a fundamental and first-higher mode. All three methods agree closely in the frequency range over which only one mode is present. The dispersion curve from the SASW method, which represents a superposition of modes, shifts gradually from the fundamental mode to the first higher mode as frequency increases. The ReMi outcome tracks only the fundamental mode over its range of analysis.

The study presented herein documents procedures to assess uncertainty in shear wave velocity determined via SASW, and demonstrates use of these uncertainty estimates to guide the inversion process to provide a quality, realistic shear wave velocity profile. Based upon the analyses performed, the inversion protocol guided by uncertainty estimates is shown to successfully invert dispersion data. For the site example presented, the trend in shear wave velocities determined via the protocol is quite consistent with the material classification and standard penetration test results available for the site. It is shown that uncertainty in shear wave velocity is a function of the number of soil layers used in the inversion. As the number of layers increases, uncertainty in shear wave velocity also increases. The results also suggest that the layer resolution of SASW inversion on soil sites is approximately 0.3048 m (1 ft).

One of the complicated aspects of the spectral-analysis-of-surface-waves (SASW) method is the inversion procedure. Artificial neural network (ANN) models can potentially substitute the inversion process. For this purpose, numerous models of different neural network types and architectures were developed with different software packages. Previous studies have shown the estimation of the subgrade properties is the most challenging aspect of implementing the ANN models. This paper focuses on training models for the subgrade layer. The results from this study were used to develop more sophisticated models to estimate all pavement stiffness parameters.

Two key aspects of any experimental technique are the ability to a) estimate the uncertainty of the measured data and b) determine how this uncertainty is mapped onto the model parameters. In surface wave testing two situations are frequently encountered in practice: either one has to compute dispersion and attenuation curves from measured shear wave velocities and shear damping ratios at a site (forward problem), or one needs to determine which set of model parameters V_S and D_S correspond to measured Rayleigh dispersion and attenuation curves (inverse problem). This article illustrates the results of a parametric study aimed to investigate how in surface wave modeling the uncertainty is projected from the measured data onto the model parameters in the solution of both forward and inverse problems.

Many surface-wave methods have focused on collecting only normal modes of Rayleigh-wave propagation. This paper presents an inversion algorithm to invert the apparent phase velocities, which include near-field information as well as normal-mode information. In the algorithm, Love-wave dispersion data are jointly included with Rayleigh-wave dispersion data to reduce non-uniqueness inherent in surface-wave methods and increase the accuracy of a resulting shear-wave velocity profile. Synthetic dispersion data were generated for typical geologic sites, and used for the verification of the inversion algorithm. A strategy to overcome the adverse effects of multiple reflections and mode conversion in Love waves is also discussed.

Geophysical techniques including Seismic Refraction and the Multi-channel Analysis of Surface Wave (MASW), were applied to define subsurface conditions and delineate underground anomalies in the southern piedmont geologic region of Atlanta, Georgia. Seismic refraction was performed to identify the approximate rock profile. Surface Waves analysis was used to further characterize the subsurface conditions in the general areas where the Seismic Refraction survey suggested the presence of relatively shallow rocks. This procedure was applied to detect hidden layers or weak zones that might be present under a shallow rock layer. The acquired data was processed using the SiesImager software suite and SurfSeis software. The information gathered was then used to provide guidance for site specific targeted geotechnical testing including soil drilling, rock coring and laboratory testing. This resulted in a cost-effective foundation design for a proposed 2,700 feet long mechanically stabilized earth (MSE) retaining wall at a solid waste facility. The wall was planned in the course of expanding the facility's capacity.

Most surface wave inversion algorithms used for geotechnical site characterization are based on a subsurface model consisting of a stack of homogeneous layers with constant shear wave velocity. In reality, the shear wave velocities and other parameters are likely to vary continuously with depth. The difference between the actual site conditions and assumed model is a source of uncertainty in surface wave testing. In this study, a surface wave inversion algorithm based on a subsurface model in which the material properties vary continuously with depth is developed and illustrated for two sites.

The spectral analysis of surface waves (SASW) technique is frequently used on land to measure the shear wave velocity profile. This paper presents an application of the methodology for underwater site investigations. Field data are collected using a bottom-towed acoustic source and a streamer of hydrophones. Multichannel data are processed by slant-stacking and fast Fourier transform to find the relation between phase velocity and frequency. Inversion processing of these dispersion curves is used to generate a continuous profile of soil stiffness below sea floor. An example case of a site investigation in the Adriatic Sea is presented. Comparison of shear wave velocity profiles obtained with downhole seismic cone and the underwater surface waves technique shows good agreement confirming the reliability of the multichannel analysis of surface waves (MASW) underwater.

It is difficult to depict uncertainty graphically. Conventional means, which rely on mapping uncertainty to graphical attributes in an image, have limited effectiveness because they require presenting additional variables and are not generally intuitive. The concept of uncertainty multiples is proposed herein to address these challenges. Uncertainty multiples are small-scale images positioned within the eyespan on a single page or screen showing the range of possible interpretations of the information. This concept is illustrated and its implementation in practice, including the role of software technology, is discussed.

Geotechnical engineering by its nature demands tools for coping with large uncertainties and variations in material properties. One such tool, which the profession has tried to adopt, is geostatistics. This paper examines the question of whether geostatistics really holds much promise for geotechnical engineering, and attempts to identify conditions that if satisfied could convert geostatistics into a real design aid for geotechnical engineers. The paper briefly looks at the origins of geostatistics, and examines its successful application to a variety of fields. It also describes the potential benefits geostatistics can bring to geotechnical engineering, and explores possible reasons underlying geotechnical engineering's difficulties in fully harnessing the power of the method. The paper conjectures that primary reasons include widespread unfamiliarity with the concepts of geostatistics, and a lack of geostatistical software tools that can be readily used in geotechnical analysis.

Well known statistical tools yield results in the form of probabilities associated with parametric values or events. Examples in geotechnical practice are the spatial distribution of soil strengths, the occurrence or non-occurrence of liquefaction, and the existence of a particular geotechnical condition at a specified location. Statistical procedures are used to fit the model to the data and to infer parameter values with some associated level of confidence. Such statistical inferences are invariably used to make probabilistic statements about field conditions or safety, and they sometimes end up in safety or risk analysis. In traditional statistical practice of the sort taught to undergraduate civil engineers, statistical inferences are based on frequency concepts of probability. The statistical results are actually the probabilities of observing the data if the assumed physical model and parameter values are true, not the probability that the model is true given the data that were observed. This is the meaning of the probabilities one finds in Kriging, Seed's liquefaction chart, or a grid-search table. Unfortunately, the geotechnical engineer really wants the reverse result, that is, the probability that the model is true given the data that were observed. Engineers are tempted to go ahead and use the result of a traditional statistical analysis as though it were the probability of the model's truth, and one suspects that many engineers are not even aware that the probability is not the one they need for further analyses or for assessments of safety and risk. Does it matter? If so, how much? Many researchers use Bayesian methods to develop proper probabilities. The present paper describes the problem in engineering terms and shows how to obtain the correct probabilities without undue additional effort. The now-classic problem of probability of liquefaction, given a seismic excitation and SPT or CPT results, is used as an illustration. Finally, the paper asks and answers the question of how seriously the probabilities of observing the data differ from the probabilities of the truth of the model, and explores the influence of prior probabilities (and hence, engineering judgment) on this difference.

Geotechnical properties vary in space with statistical parameters (mean, deviation, correlation length) that are characteristic for each sediment and formation history. The effects of spatial variability on the macro-scale mechanical properties of soils are investigated using Monte Carlo non-linear finite element simulations. Boundary conditions include radial loading, zero-lateral strain loading, and drained/undrained deviatoric loading. Numerical results show that internal heterogeneity leads to higher compressibility, lower horizontal load transfer, and lower shear resistance in both undrained and drained loading.

Soil variability is a complex attribute that can affect geotechnical engineering design. This paper presents the initial stage of a study into the variability of soil proprieties at the Port of Navegantes, southern Brazil. This study is based on laboratory and field tests that were done as part of the Port enlargement planning. The database consisted of SPT, Vane, soil characterization, oedometer and triaxial tests. The terrain comprises three compressible organic clay layers, separated by variable thickness sand layers. A basic statistical parameter calculation, and an initial autocorrelation study are presented using these data for each clay layer, for planes of constant elevation and depth.

The classical Anderson-Darling test for Gaussianity cannot be applied on correlated data. It is possible to circumvent correlation by resampling the data at wider spacing. A simple resampling criterion is developed using digitally simulated standard Gaussian realizations following a single exponential correlation structure. The effects of resampling on Gaussianity assessment are assessed on actual normalized cone tip resistance profiles from highly homogeneous soil units.

It is rarely appreciated that the sample autocorrelation function is a non-stationary stochastic process with mean and variance that are functions of the lag distance. For Gaussian processes, some complex formulae for the mean and covariance of the sample autocorrelation function are available. Analytical solutions for non-Gaussian processes are probably intractable and none seems to be available. A more hopeful strategy is to exploit growing desktop computational power and increasingly powerful simulation techniques for stochastic processes to perform bootstrapping. Numerical results presented in this study show that fairly accurate mean estimates of the sample autocorrelation function can be obtained for both Gaussian and non-Gaussian processes using bootstrapping. Variance estimates are less accurate, but even crude estimates are useful in identifying the level of noise at large lags and reducing misinterpretation of how the actual autocorrelation function decays with lag distance.

Geotechnical data exchange with industry, academia, governmental agencies, and organizations could be easily accomplished with uniform standards. Software producers would also benefit from the deployment of uniform standards, which were nationally marketable and compatible with other software developers. The Federal Highway Administration (FHWA) in conjunction with the Ohio Department of Transportation (ODOT) formed a group to develop data dictionaries and data formats for geotechnical management systems. The group is coordinating its efforts with other national and international agencies and groups. The initial focus is on data transfer standards. The standards will likely be adopted as both national and international standards.

The AGS format is a digital data interchange format for the geotechnical community, consisting of a data dictionary, rules and the file format itself. The Association of Geotechnical and Geoenvironmental Specialists (AGS) set up a Working Party in 1991 to reduce the proliferation of data formats and establish a format to transfer of data between systems. The AGS Format is updated and extended in response to industry requirements. AGS3.1 (Dec 2004) includes monitoring and instrumentation data. In future the AGS Format will include new computing techniques and data management. The use of the Format at work has created savings in time and resources.

The use of geotechnical database software for handling digital ground data is not new, but recent improvements in computing power have enabled designers to make better use of this technology. This paper describes how a global design office is using geotechnical database software, illustrated by three case study examples. The key benefits are identified, as are some potential pitfalls. Data transfer between organizations is discussed with particular reference to the use of the Association of Geotechnical and Geoenvironmental Specialists (AGS) digital data transfer format commonly used in the UK. Examples are also given where geotechnical databases and digital data transfer have been extended to related applications such as laboratory test scheduling and visualization of pile installation data.

Modifying design procedures during the active construction phase of a project in response to the measured performance of key structural elements or ground movements can yield significant productivity and cost benefits. However, site monitoring schemes implemented to record these measurements often generate a significant volume of data and the time taken to process and disseminate it is often complicated by incompatible systems or formatting conflicts between the users of these data. This paper describes the use of the AGS data format protocol for the transfer of processed site data, and the development of a web based data visualization system used to view the output from a recent field monitoring project.

In 1991, the UK Association of Geotechnical and Geoenvironmental Specialists (AGS) published a common format for electronically organising geotechnical data in order to facilitate data sharing. Since 1991 the format has been accepted and implemented by a number of international government bodies and consultants and has paved the way for a revolution in the methods available to engineers for interpreting Site Investigation data efficiently. The AGS format has now been represented in XML (AGSML) which has been developed by integrating two commonly used standards, AGS and GML. This paper describes the motivations and techniques used for developing a GML compliant version of the AGS data transfer format. It also describes an example web application that illustrates the benefits of the AGSML to users.

The spatial distribution and correlation of soil attributes greatly influence the extent and magnitude of soil liquefaction failures during earthquakes. Existing techniques for analyzing earthquake-induced soil liquefaction failures do not always take advantage of the spatial nature of geotechnical data; therefore, adoption of techniques designed for spatial data directly leads to improved identification of at risk soil regions. This paper presents a customized three-dimensional geographic information system (GIS) for visualizing and analyzing liquefaction potential across a site. The GIS has been designed to incorporate stratigraphy as well as sample-specific soil attributes.

The long recurrence period and high consequence earthquakes events in the New Madrid Seismic Zone have caused some federal agencies (e.g., NEHRP, FHWA) to look at the more densely populated areas where higher seismic risk is present. This paper presents the data collection, interpretation, and analysis of the geotechnical information required for an earthquake loss estimation study in St. Louis metro area. The loss estimation study was limited to the highway transportation system, where only the major highways were considered. The project information was processed using a GIS, and the subsequent loss analysis was executed using the HAZUS-MH program.

This paper describes the creation of a database to store and provide access to historical geotechnical and pavements information from hundreds of construction projects in Kansas. Records of subgrade soil and pavement information were scanned to an accessible electronic format and key data fields were entered into a database. The geographic coordinates of sampling locations were determined, where possible, and entered into the database. These data may be imported to and analyzed in a geographic information system (GIS). Multiple analyses were conducted using the information from the database, and the accuracy of the data entered was evaluated.

Heave induced infrastructure distress hazard analyses play a key role in assessing the potential consequences of soil heaving in relation to existing facilities and the planning of new ones. In this work, a variety of GIS-supported spatial analysis procedures have been integrated for assessing and mapping potential heave induced infrastructure distress hazards in a pilot DFW metroplex area, where expansive soils predominate, using the computational capabilities of PC-supported ArcInfo software. Distress hazard assessments are based on soil plasticity index values, swell-shrink potentials, and soluble sulfate contents.

Stability of a waste rock pile at an abandoned mine site was evaluated to identify the need for stabilization. The geometry of the rock waste pile is not uniform, either in terms of the surface slope or thickness. A GIS-base program was used to model the possible geometry of the pile based on topographic data. Large-scale measurements of strength and the pile geometry data were combined with the GIS program to provide an estimated factor of safety for all locations on the pile based on the infinite slope method. The GIS-based approach was found to be an efficient means to identify pile characteristics and to provide and reasonable first-order stability assessment.

Southern California was devastated this past fall with a series of sweeping wildfires, which blackened in excess of 375,000 acres of land. GeoSyntec Consultants assisted the City and County of San Diego in implementing a rapid assessment of fire damage and potential for debris flows following impending rain events. Data was collected from field teams employing GPS enabled ruggedized PDAs. This data was then assimilated directly into a Database/GIS system. To assess the overall potential for increased erosion response, slope, soil type, and burn severity data was integrated using a GIS platform to produce a Post-fire Hazard Index of Relative Erodability (PHIRE) map. This paper provides an overview and site specific examples of the tools and techniques applied as well as a summary of lessons learned and a discussion of the appropriateness of the technologies as a function of the magnitude and complexity of the task at hand.

As interest in developing offshore resources increases, so too does the need to characterize submarine mass and determine the probability that these events will affect new developments. In order to predict the likelihood of submarine mass movements, it is necessary to understand the conditions that have caused previous movements in the area. A detailed morphological analysis integrating bathymetric and seismic reflection profiles can help to clarify the underlying mechanisms which may lead to mass movements. In order to complete this type of analysis in the Saguenay Fjord, several software tools were used in conjunction.

Based on the idea of Scientific Visualization, this research is aimed to visualize the complex geoscientific data to support the mapping work of the Björkö Energy Project, which has an ultimate goal to place a heat exchanging mechanism at the most suitable location in the subsurface. The production from this impact crater structure is expecting to supply the heating use for the great Stockholm area. The various point data types were compiled to diverse maps according to their characteristics. Several GIS and numerical tools are introduced integratedly to accomplish the work. The research in addition helps to streamline the data and maps processing activities carried out by the varied working groups.

This paper presents the features and benefits of an on-line geotechnical database. The on-line database is tailored to follow specific engineering needs, provide effective data management system and satisfy client's requirements on large site investigations. The development of an engineering database implies integration of computer applications and GIS concepts. This system is specifically designed to provide assistance in on-line tracking of the status of geotechnical study and real-time reporting. The greatest advantages of such database are easier preliminary geotechnical assessments of new sites by analyzing existing locations. The paper also describes the structure of this client-server application that provides remote access to the database using geo-referenced interactive query tools.

In an effort to manage the tedious slope maintenance works of mountain highways in Taiwan, a Slope Management System is developed based on a well designed MIS system in combination of the Geography Information System. The Slope Management System contains four major components: the inventory database, historical hazard information database, maintenance record database, and the expert system for mitigation strategy. All the information stored in the database and analyzed results can be visualized by taking the advantage of powerful display functions of GIS. In this paper, the detailed program structure of Slope Management System as well as operation example of a demo project will be introduced. Purpose of this paper is to introduce a helpful tool for slope mitigation and maintenance management.

Geographic Information Systems (GIS) are tools for organizing, analyzing, and presenting spatial data. GIS can be used by geotechnical engineers to aid preliminary assessment through final geotechnical design. This paper introduces GIS and applications of the technology. GIS tools can be used to integrate existing data with project specific data; identify potential geological hazards; plan and track field work; create maps and figures; and improve communication. These tools can help identify potential barriers to project completion early in the design process that may help to avoid later costly redesign. Actual projects utilizing geotechnical applications of GIS are presented to illustrate.

The Geotechnical Engineering Office (GEO) of the Ohio Department of Transportation (ODOT) has embarked on a concerted effort to develop a comprehensive geological hazard management system (GHMS) to enable better management of data and activities related to planning, design, construction, and maintenance projects. There are five geological hazards to be eventually included in the Ohio GHMS: rockfalls, landslides, underground mines, karst, and shoreline erosion. This paper presents the development of a landslide hazard rating system. The associated statistical and cluster analysis results of 37 Ohio landslide sites validates the effectiveness of the rating system.

One important aspect in the design of many geotechnical structures such as tunnels, retaining walls, and piles is the serviceability failure performance of the structure, i.e., when the actual displacement of the structure exceeds the maximum allowable displacement. A risk-based approach to serviceability performance "failure" is necessary to incorporate systematically the uncertainties associated with various design parameters. This paper demonstrates the use of an integrated neural network-reliability method to assess the risk of serviceability failure through calculation of the reliability index. An illustrative example for a braced retaining wall is presented using this approach.

Over the last decade artificial neural networks (NN) have been proposed as alternatives to more conventional elasto-plastic based constitutive models. A NN material model can be used in a similar fashion to conventional models in the solution of boundary value problems. The authors have developed Self Learning in Engineering Simulation analysis framework which extracts relevant soil behavior using boundary measurements of load and displacement, facilitated by use of NN constitutive model. This framework shifts focus from the specific soil model to the stress-strain database used in material model training and development.

Roughness of Portland Cement Concrete (PCC) Pavements is affected by specific design features as well as materials, subgrade, traffic, and climatic conditions. In this study, a sequential Artificial Neural Network (ANN) approach was used to develop a time-dependent roughness prediction model Utilizing a two-stage training approach and through numerous training, testing, and validation processes, a three-layer (19-10-1) time-dependent ANN-based roughness prediction model was developed. The developed model produced output values that are close to the actual (measured) roughness IRI (International Roughness Index) values. Accordingly, it was able to project the time-dependant roughness behavior with a reasonably high R² = 0.90.

To investigate the serviceability reliability of a braced excavation system, a means has to be established for estimating wall deflection in the braced excavation. Traditionally, the wall deflection and ground settlement are "predicted" using finite element method (FEM) and/or other simplified methods. In this study, artificial neural networks (ANNs) are developed as an alternative of estimating the maximum wall deflection. The developed ANNs are validated with the collected 8 case histories of deep excavation that were not used in the development of these ANNs.

This paper presents the methodologies and results of two types of neural networks used to estimate the unconfined compressive strength (UCS) of weakly cemented sandstones from geophysical log data. The first neural network used 29 different logs as input and predicted UCS values at 8 cm depth resolution that were in good agreement with measured values. The second neural network used an innovative approach to improve the depth resolution and detection of thin bedding by relating changes in high resolution logs (e.g. bulk density or resistivity) to changes in strength. Preliminary analyses used to predict the undrained shear strength of marine clay illustrate the potential of this new approach for predicting the strength of weakly cemented sandstones.

Accurate detection of a contaminant source is vital to the management of groundwater restoration projects. We developed a technique for identifying the contaminant source areas that combines site data, geostatistics and artificial neural networks (ANNs). The methodology involves replicating the kriging methods with ANNs to provide estimates of spatially dependent concentration fields, and for quantifying the uncertainty associated with the estimates. Once trained the ANNs approximate the results of ordinary kriging in a more computationally efficient manner. This provides a bi-directional prediction (i.e. forecast the future plume, as well as, the original source), which is impossible for many physics-based models.

The Water Pressure Test is frequently used for evaluating the permeability of rock masses by measuring the volume of water taken in a section of a borehole during given time intervals. In jointed rocks the relation between the absorption rate and pressure is not linear and a number of different views exist for determining the flow regime and the permeability of a test section. Considering these views a new method is introduced using Neural Networks for predicting the permeability of a testing section, which shows that Neural Networks are capable of predicting permeability values of jointed rock masses with high accuracy.

Soil proprieties are typically determined from a limited number of in situ or laboratory tests performed at a specific site. The results of these tests may be used to estimate soil properties of the whole site by means interpolation techniques such as linear, polynomial, statistical or machine learning methods. In this paper, a Standard Penetration Test (SPT) database from the port of Navegantes, south Brazil, is used for analysis. Geotechnical mapping of SPT blow counts is made using classical interpolation methods and the neural networks technique, and their performance compared.

We present a new subsurface characterization methodology that combines primary data and correlated secondary data with a counterpropagation artificial neural network to create parameter estimates. This methodology is applied to a subset of air permeability, compressional-wave velocity and electrical resistivity measurements that were sampled on a 2-dimensional block of Berea sandstone. Similar to traditional geostatistics, the ANN can incorporate anisotropy and uncertainty to account for patterns generally observed in the geologic setting. The ANN estimates are data-driven, can incorporate large amounts of multiple data types, do not require the computation of covariance matrices and can produce realizations in real time.

Sediment properties are spatially variable at all scales, and this variability at smaller scales influences high frequency ground motions. We show that surface shear-wave velocity is highly correlated within San Francisco Bay Area sediments using shear-wave velocity measurements from 210 seismic cone penetration tests. We use this correlation to estimate the surface sediment velocity structure using geostatistics. We find that the variance of the estimated shear-wave velocity is reduced using ordinary kriging, and that including this velocity structure in 2D ground motion simulations of a moderate sized earthquake improves the accuracy of the synthetics.

Analyses of seismic data recorded at dense instrument arrays provide insight into the causes of the spatial variation of seismic ground motions. This paper investigates amplitude and phase variability in seismic data recorded at a SMART-II dense subarray during the Chi-Chi earthquake. It is shown that both amplitude and phase variability contribute to the ground motion spatial variation, and there is a correlation pattern in the variability of amplitudes and phases at individual stations around a coherent component, common at all recording stations. It is also noted that larger variability is obtained from the data at the SMART-II subarray, located on firm gravel deposits, than that from the data at the deep sediment site of the SMART-I array.

Results of 1D ground response analyses are typically not incorporated into probabilistic seismic hazard analyses (PSHA) in a statistically robust way. Often ground response is incorporated into PSHA using deterministic amplification factors. This simplistic method generates results that are intrinsically arbitrary and often unconservative. The main problem in probabilistically linking PSHA and ground response lies in quantifying the dispersion that is appropriate for use with ground response analysis results. We review two alternative procedures for quantifying this uncertainty and illustrate their differences with respect to dispersion values of spectral acceleration at the surface for various site conditions.

Deterministic liquefaction analysis ignores uncertainty regarding size and nature of future earthquakes, stochastic response of the soil column, and the variability in soil resistance to liquefaction. This paper provides a framework to evaluate the annual probability of liquefaction considering both aleatoric and epistemic uncertainty. The methodology is based on the approach of the recent FEMA design codes. Results of probabilistic seismic hazard assessment (PSHA), site response analysis and conventional liquefaction analysis are folded together to define annual probability of liquefaction. Assessment of the effects of uncertainty is illustrated through an example application to an industrial site.

This paper presents examples of the effects of soil heterogeneity in forward and inverse site response problems. First, it is shown that deterministic descriptions of soil profiles may be adequate for strong motion site response analyses of horizontally stratified formations. Conversely, a non-level ground site response example shows that for non-horizontally polarized wavefields controlled by the characteristic length of ground asperities and material heterogeneity, results are strongly frequency-dependent. Finally, it is shown that deterministic descriptions of the continuum may result in unrealistically high attenuation values in seismogram inversion problems. These site-specific examples suggest that due to source- and path-originating ground motion uncertainty, probabilistic seismic hazard assessment should account for spatially varying formations when opting for high-frequency predictions.

A seismogram inversion algorithm, comprising a genetic algorithm in the wavelet domain in series with a least-square operator in the frequency domain, is proposed for the efficient estimation of dynamic impedance profiles using downhole array recordings. Results are presented for selected aftershocks of the M_w 7.0 Miyagi-Oki Earthquake in Japan. Using the inverted profiles, the nonlinear site response is next estimated and compared with the mainshock recordings. Finally, inversion of the mainshock site response is employed. The agreement between the forward and inverse large strain properties illustrates the value of strong motion site response data in validating site response methodologies and understanding the mechanisms that govern nonlinear site effects.

The California Department of Transportation (Caltrans) is taking advantage of and adopting innovative technologies to improve the management of its growing investment in geotechnical data. The GeoResearch Group (GRG) and the Geotechnical Data Management Committee (GDMC) are working to develop a comprehensive data management strategy for borehole, lab test, and insitu test data. Activities include the development of standardized data models and reporting formats for geotechnical information, standardization of software tools, evaluation of data collection technologies, and optimization of workflow practices. Caltrans' participation in international initiatives through COSMOS/PEER-LL and FHWA is helping to establish a global model for data interchange.

Minnesota Department of Transportation (Mn/DOT) has advanced over 20,000 soil borings and CPT soundings in the past 46 years. An electronic database of point data was established in the 1970's. A web-based interface and set of query tools was developed in 2003. An intranet version is being used; the public version is expected to be ready in fall of 2006. With minor changes to the data nomenclature, Mn/DOT's system is expected to be fully compatible with evolving geotechnical management systems being developed by a number of cooperating international agencies. Development of the Mn/DOT system, obstacles, difficulties, and benefits are described.

A multi-tier object model based on Microsoft .NET Framework for engineering analysis and design procedures has been proposed. Besides its own specific data and algorithm definitions, the object is also a container of other predefined object collections; therefore, an object can be as simple as one SPT-N value or as complicated as one construction project. All physical engineering objects can be virtually described by the proposed model as long as all the components have been defined. Based on the proposed model, a preliminary web site focused on geotechnical applications has been established and introduced in this paper.

Production of drafted soil boring logs is very time consuming and costly because of the outdated process of hand written entry of descriptive data and measurements. As a process improvement, a software application was developed for use on a personal digital assistant. The man hour savings for logging and producing final logs for 20 boreholes using this software was approximately 200 hours. The advantages are real-time production of logs and cross-sections in the field, increased quality, elimination of transcription and review time, reduction in turnaround time, and in field, on the fly decision making.

Described is the architecture of WebDACS, a web-based data acquisition and control system for geotechnical and environmental monitoring instrumentation. WebDACS automatically collects data from field instrumentation and delivers it to a central data store for visualization and reporting though a standard web browser. The system's flexible architecture enables facile support for a variety of instrument protocols. Three main components of the system are a field data manager, a web-based relational database, and server-based data access layer that interfaces with the Flash user interface component. A flexible synchronization framework facilitates remote control of acquisition parameters and asynchronous reconciliation between multiple field agents and the data store. User-specific privileges control data visibility and access to acquisition control parameters via password protection.

All too often geotechnical organizations design databases to store information in a for the purpose of creating specific reports, generally borehole logs. This can lead to data that has limited usage, is difficult to enter, and is nearly impossible to validate electronically. This paper defines the problem and presents better design techniques for creating true databases that are easy to populate, can be validated electronically, and can be used over a wide range of applications.

Hickory Log Creek Dam is a proposed 55 meter high roller compacted concrete dam located on a tributary of the Etowah River near Canton, Georgia. The site characterization involved several approaches that facilitated the rapid foundation investigation schedule. These included identification of critical data needs, design of the program to collect these data, and selection of preferred data acquisition and evaluation. The foundation area of the dam is composed of fresh relatively unfractured mica schist in the stream valley and a mantle of residual soil and partially weathered rock on the abutment hillslopes.

The purpose of this study is the data modeling for several main aspects of road tunnel construction in Greece: general and economic data, geometrical, geological and geotechnical data, monitoring systems during and after the construction, typical cross section data and finally, special construction problems and their treatment. The implementation of the data model in a database is expected to provide easy access to information concerning the existing tunnels to all interested parties. Issues discussed involve designing and programming of the application, special points of interest regarding the manipulation of data as well as future developments in the area of management and synthesis of tunnel construction data in Greece.

This paper demonstrates how the implementation of a standardized data format, specifically the Association of Geotechnical and Geoenvironmental Specialists (AGS) data format, for collecting geotechnical and geoenvironmental data improves management of data from `cradle to grave'. Particular improvement was noticed in the data collection phase by implementing the collection of data in the field using PDA's with AGS data format. A case study is described where financial and technical benefits were realized by combining a standardized data format with an application developed using open source software.

Geotechnical laboratories have traditionally tracked laboratory samples with hand-written labeling systems and recorded test data in hand-written records. These records are then used to produce hand-written reports or manually entered into data reporting software to generate reports. This approach consumes a lot of man-time and presents many opportunities for errors. GeoTesting Express has developed and implemented a new process for sample tracking, data management and test reporting to improve the laboratory's performance. Central to the process improvement is the design and implementation of a new Laboratory Information Management System (LIMS) which allows for sample tracking and status updates while also eliminating hand written data and manual data entry for production of reports. This paper shows how the implementation of this new LIMS has benefited our laboratory by decreasing turnaround time, decreasing production costs and reducing errors.

Cω is a strongly typed, data oriented programming language that bridges the gap between between semi-structured hierarchical data (XML), relational database (SQL), and the standard data types present in object oriented programming language. The langrage has been recently introduced by Microsoft research center. Because of its comprehensive data handling features it offers a wide range of advantages in Geo Informatics Systems. This paper examines the role and benefits provided by Cω to Geo Informatics Systems (GIS) in the areas of geotechnical database management, Geotechnical Markup language (GeotechML), and engineering information processing. Besides these, the paper discusses the powerful model of concurrency that Cω offers, which is applicable, both to multithreaded applications running on a single machine and to the orchestration of asynchronous, event-based applications communicating over a wide area network systems.

The layout of the monitoring system and the type of devices to be installed in the lower of the two concrete face rockfill dams of the Siah Bishe pumped storage scheme in Iran are described. The scheme uses the most up-to-date instruments, including in-place inclinometer and electro-levels. Automated data acquisition, data transmission, processing, and plotting are other advanced features of the system. An alarm can be triggered when a measured quantity has reached a critical level.

Environmental data analysis typically requires multiple software packages. Data analysis is performed by junior staff, and results in static results which are delivered to project managers. Documentation and audits of data analysis are challenging due to the multiple steps involved. Changing analysis parameters is expensive and time consuming. We developed a web application which performs environmental data analysis for borehole logs using web services which wrap around standard analysis and graphing tools. This allows end users to perform data analysis without requiring knowledge on data formats, location or application packages. Access to the web application and underlying project related data is password controlled.

Regional cooperative efforts between the States, Port Authority, USEPA, and the USACE have allowed the Port of New York and New Jersey to not only maintain but also deepen the main shipping channels using innovative beneficial use technologies. Since the cessation of ocean disposal in 1997, over 6 million cubic meters of dredged material have been used beneficially for landfill cover, mine reclamation and brownfield remediation with substantial environmental and local economic benefit. This paper outlines the strategies used to overcome the significant logistical, regulatory and economic issues that stood in the way of achieving the transition to beneficial use.

A nonlinear programming model has been developed to assist in the development of dredging plans at open water disposal sites. The model has been developed based on conditions at the near-shore open water disposal site near the mouth of the Columbia River. The optimization model considers available capacity of cells within the disposal area to produce a dredging plan that minimizes mounding within the site. Ultimately, the optimal dumping plans will be loaded in the MDFATE computer program to simulate various stages of the dredging disposal cycle. Initial testing of the optimization model indicates that it produces reasonable dumping plans.

This paper presents a higher order gradient formulation to model the effect of anisotropy in the deformation in granular materials. The effects of anisotropy are taken into consideration through the modification of the mobilized friction. The latter is assumed to be a direct function of the fabric tensor. The formulation has been implemented into a finite element code and used to simulate simple shear tests on dry sand.

Shear band formation in granular soil masses is usually treated as a bifurcation problem and orientation and evolution of thickness of shear bands are related to grain size. Classical continuum mechanics considers the interaction of microstructural units of the material through stresses and displacements of material points. However, in reality interaction of grains may include rotations, slips and relative translations. In this paper, the importance and relevance of length scale on the constitutive modeling of granular materials is reviewed by comparing Classical and Cosserat Continua in numerical simulations.

To investigate the relationship between fabric anisotropy and macroscopic stresses of granular soils, three-dimensional discrete element analysis was performed. Eight triaxial stress probing tests were simulated, and the variation of the degree of fabric anisotropy was estimated in terms of the cross-anisotropic fabric tensor. Regardless of the direction of stress paths, there was a unique relationship between the degree of fabric anisotropy and the stress ratio in lower stress ratios ranging from –0.1 to 0.6.

A model developed for the rate of tree root water uptake is applied numerically based on finite element analysis, to investigate the effects of the soil, tree and atmospheric parameters on the ground behaviour. The influences of potential transpiration rate, permeability coefficient, and the maximum root length density are studied and quantified. Although the rate of transpiration increases the soil matric suction and the ground settlement, permeability (saturated) decreases the matric suction generated and the corresponding settlement. The maximum root density also affects the change in peak matric suction as demonstrated in the paper.

The behaviour of filled rock joints depends on the properties of the joint and of the fill material. In this paper, the authors present a new model (called CSDS) that can represent the shear and normal behaviour of clean and filled rock joints. From a geometrical analysis of joint surface asperities and fill thickness, equations are established to represent the evolution of joint parameters using the properties of fill material. The rock joint shear constitutive model CSDS is modified to simulate the complete shear behaviour of filled rock joints. The validity of the proposed approach is then assessed through applications to laboratory test results.

Probabilistic methods have been used to evaluate geologic hazards in subsurface conditions if a simple pattern bolt spacing would increase from 5 to 7 feet. Traditional and deterministic approach employed during design was expanded to include distribution functions for joint sets. The Monte Carlo simulations and probabilistic predictions were used to investigate if increasing of the pattern will change stability of blocks. The presented statistical simulation modeling method was calibrated using well known field observations. The unstable area probability maps were created for both patterns. The one basic and two additional criteria were developed to evaluate for which tunneling direction a bolting pattern could be increased.

The response of clay is highly dependent on straining and loading rate. To obtain a realistic prediction of the response for time dependent problems, it is essential to use a model that accounts for rate effects in the stress-strain-strength properties of soils. The proposed model has been expanded from the existing SIMPLE DSS framework to account for the strain rate effects on clays in simple shear conditions. In accordance with the findings in the existing literature, soil response displays a unique relationship between shear strength and strain rate. The predicting model is illustrated with a limited test data.

Design of a structure on expansive soils must consider the depth of wetting that can occur during the life of the structure and the associated heave. Two-dimensional seepage analyses were conducted for soil profiles typical to the Denver area to evaluate the migration of the wetting front. Predicted values of potential heave versus time were computed based upon the migration of the wetting front for sites with low, moderate, and highly expansive soils. The predicted heave in the lifetime of the structure is compared to the predicted maximum free-field heave for sites with various boundary conditions.

"Composite material" signifies that two or more materials are combined on a macroscopic scale to form a material exhibiting the quality superior to its constituents (Jones, 1975) by capturing the strength of each constituent. Combining the strength of Ottawa sand (compression) and geosynthetic (tension), this geo-composite is strong in both tension and compression. Finite element analyses are performed on cubic samples of this geo-composite to evaluate its equivalent transversely isotropic properties, which are then written as functions of the isotropic linear elastic properties of sand and geosynthetics, and geosynthetic spacing, etc using regression analyses.

Cyclic shear strain plays a key role in the determination of soil behavior in geotechnical earthquake engineering. The aim of this research is to explain the context of threshold strain that delimits a transition state between small and large deformations. Two methods were used to model the degradation of shear modulus against shear strain: best fit line and best fit curve. A good agreement was observed between experimental results and modeled curves.

Lumped Parameter (L.P.) models have been used widely to simplify the analysis and obtain reasonable dynamic response (i.e., displacement and acceleration) of complicated real-world systems under effects of dynamic loadings. Since analytical (closed form) solutions of ordinary differential Equations (ODEs) of motion representing single/multi degree-of-freedom (D.O.F) L.P. models are usually not possible, an appropriate numerical time-stepping methods for integration of ODEs can tackle such problems. The R-K-N method was introduced to solve non-homogenous linear ODEs representing a 2-D.O.F L.P. model. The R-K-N method produced a significant consistency with the analytical solution results and seemed to be a reliable numerical method.

This paper compares the stability properties of several constitutive models under simple loading conditions. Results from simulations, cast within both the regimes of small and large deformations, are presented. The discussion emphasizes the roles of the different components of isotropic plasticity models on localization predictions (e.g. formation of shear bands and slip/failure surfaces). Incidentally, the provided examples show that, for some applications, stress-strain behavior alone is not the best indicator of the suitability of a constitutive model. Understanding of the aforementioned elements is useful in the selection of appropriate constitutive models for specific applications.

Scour occurs when the erosive capacity of water exceeds the ability of the earth material to resist it. The erosive action of water differs for laminar and turbulent flow. The paper shows that shear stress characterizes the erosive capacity of water in laminar flow. In the case of turbulent flow, turbulent pressure fluctuations characterize it. The indicator parameters quantifying the relative magnitude of the erosive capacity for laminar and turbulent flow also differs. The paper investigates inconsistencies in indicator parameters currently used in practice and provide guidelines for correct use.

River channels naturally migrate through meanders. This migration can cause major damage to bridge structures. For geotechnical engineers, hydraulic engineers, and structural engineers in Departments of Transportation in the country, it becomes important to evaluate the potential future movement of such meanders. This paper describes some very large scale laboratory experiments simulating meander migration in sand and associated results. To our knowledge these are the largest such experiments in the world. The data indicates that the meander actually widens the river on both sides but more so on the outside bank than the inside bank. Rates of meander migration are presented and compared with existing knowledge.

This paper presents a simplified method of analysis for pile groups founded in liquefying soil. The method involves two main steps. First an effective stress based ground response analysis is carried out to obtain the maximum ground displacements along the pile and the degraded soil modulus over the depth of soil deposit. Next a dynamic analysis is carried out for a single pile in the group assuming that each pile in the group behaves in the same way during the earthquake loading. The method has been verified using centrifuge data, where soil liquefaction has been observed in laterally spreading ground. It is demonstrated that the new method gives good estimate of pile behaviour, despite its relative simplicity.

This study presents an analysis and a visualization of the effect that the pile shape has on the penetration resistance of driven piles in crushable granular materials. Discrete Element Method (DEM) simulations of piles with different shapes (flat tip, open pile, triangular tip) being driven into a previously compacted uniform crushable soil are presented. The results from the DEM simulations showed that the shape of the driven pile has a significant influence on the development of penetration resistance and particle crushing.

Response of individual piles to oblique pull is one of the most complex soil-structure interaction problem in the field of foundation Engineering. For the analysis, it is essential to take both elastic and plastic properties of soil, as both these properties occur along the embedded length of the pile. Herein, a generalized solution is presented for piles under oblique pulls taking into account the elasto-plastic nature of cohesionless soil. The flexural behavior of pile in an elasto-plastic soil is considerably influenced by the variation of plastic resistance, soil modulus variation and the boundary conditions at the top.

This paper describes the history of the method of characteristics as the wave equation solution, and the author's experiences with this solution. The Dutch research institute TNO started the development of the wave equation program TNOWAVE in the late 1970's; today the program has a worldwide application in the field of pile testing. This paper describes its development, and its relation to today's applications for driveability studies (PDPWAVE), Dynamic Load Testing signal matching (DLTWAVE), Pile Integrity Testing signal matching (SITWAVE), and Statnamic simulation (STNWAVE). The paper also highlights the algorithms behind the program, and finally identifies areas for further development.

A new system of multiple dynamic strain sensors and accelerometers embedded in test piles provides direct synchronous measurement of force and acceleration at various locations within a pile during high strain dynamic pile testing. This instrumentation system creates an opportunity to explore side and end bearing pile resistance distribution with a higher level of confidence and reliability than from top measurements alone. Dynamic testing results using embedded transducers are presented for a 16-inch Auger Pressure Grouted Displacement (APGD) pile. The procedure is explained to estimate static side and end bearing components by matching force and/or acceleration data at the pile top and tip using the CAPWAP program. Static load and displacement characteristics at the pile top predicted by CAPWAP are compared to static pile load test results.

Drilled shafts socketed into rock have been widely used as a foundation system for bridges to resist lateral loads. This paper presents a 3D finite element model to simulate the lateral response of drilled shafts in rock mass using ABAQUS. As an application of the modeling, the push-pull moment resistance, which is attributed to the mobilization of push and pull vertical side shear forces on shaft due to the rotation of a drilled shaft under moments, is investigated. It is found that the push-pull resistance is not significant for a large diameter drilled shaft in rock under large moments.

An analytical model based on general shear failure mechanism of logarithm spiral type has been developed for calculating directly bearing capacity of foundations, q_ult from cone resistance, q_c. The transform of failure mechanism from shallow to deep foundation, and scale effect has been considered in the proposed method. The proposed method has been compared to the measured capacity ranging from 3 to15 kg/cm² of 16 full scale footing static load tests located in different soils, and CPT soundings as compiled in a database. The calculated statistical error for validation indicates optimistic results of capacity estimation for proposed method which is simple and routine.

This paper is aimed at highlighting the importance of Kinematic Seismic Response of Piles, a phenomenon often ignored in dynamic analysis. A case study is presented where the end bearing pile is embedded in two layer soil system of highly contrasting stiffnesses; a typical case where kinematic loading plays important role. The pile soil system is modeled as continuous system and as discrete parameter system; both are based on BDWF (Beam on dynamic Winkler Foundation) formulation. For discrete parameter system, a finite element software SAP2000 is used and the modeling technique of kinematic interaction in finite element software is discussed. For pile soil system modeled as continuous system, a general MATLAB code is developed capable of performing elastic site response analysis in two layer soil system, solving differential equation governing kinematic interaction, and giving as output the maximum ground displacement, maximum pile displacement, rotation, moment, and shear distribution along pile length. The code will further be utilized during the course of my PhD research for parametric study and data generation for Artificial Neural Network Application to predict maximum moment and its location along pile length.

The gathering of information relative to the casting process has long been the major thrust of quality control for cast-in-place pile evaluation, and there have been significant advances that enhance the quality of data obtained during casting. Additionally, systems are now available that provide the capability to electronically gather information such as applied torque, crowd, and tool rotation and penetration rates in a form which also allows for a quantitative examination of the drilling process. In general, this aspect of installation has been heretofore evaluated only subjectively in the United States, if at all. New processes for drilled displacement pile design and verification are emerging as a result of the quantity and quality of data that can now be made available. This paper describes how the collected and processed installation data can be used as an adjunct to Geotechnical site characterization and as a verification tool with respect to pile capacity. The analytical development of the methodology for processing the acquired data is discussed and application is illustrated through examples using specific project information from a variety of geologic settings.

Methods to calculate the pullout load-displacement behavior are important for the design of micropiles used for a variety of rehabilitation projects that require enhanced pullout capacity and vertical deflection control. The "t-z" method is a widely used soil-structure interaction model for such load-displacement behavior. Using a "t-z" model and the Monte Carlo simulation process, probability distributions were determined for micropile pullout capacity at the service limit state. These probability distributions were analyzed to develop methods for determining the probability of micropile failure at the service limit state. The developed methods were utilized to obtain resistance factors that can be applied to LRFD based service limit state design for micropile pullout. The probabilistic analysis presented in this paper is based upon production pullout load tests performed on approximately 120 micropiles used for seismic retrofitting of the 580/980/24 freeway interchange in Oakland, California, U.S.A. For this project, in addition to the ultimate design capacity, the micropiles were required to satisfy the serviceability design capacity at a maximum deflection of 0.5 in. (1.27cm).

Dynamic high strain and static pile tests were performed on two auger pressure grouted piles (APGP) using a network of transducers embedded near the tops and tips of the piles. The results of the dynamic tests are presented in comparison to those of a nonlinear, finite element model that approximates the dynamic behavior of the pile-soil system. The analysis represents an alternative approach for evaluating high strain dynamic pile tests, and provides a potential technique for evaluating the mobilization of side friction and end bearing. The successful use of embedded transducers represents an opportunity for foundation to routinely measure force and acceleration at the pile top and tip during dynamic and static pile testing. Comparison of finite element results to measured parameters indicates a strong dependence on pile loading rate, and future models need to include soil resistance changes as a function of loading rate or pile velocity.

The Authors have recently proposed an idea to define the parameters of a logical nonlinear Winkler soil model. In the current paper, the capability of the model will be verified to evaluate the response of grouped piles beneath a superstructure. The results are then compared with those from available physical model data and 3D FE analysis to confirm that our simulations can predict the behavior of pile groups with good accuracy.

The aim of the present communication is to investigate some aspects of the role exerted by active faults in anthropogenic land subsidence over a regional scale. The importance of regional faults depends on a variety of factors including depth of the depleted reservoir, fault orientation and size, geomechanical properties of porous medium, pore pressure drawdown induced by fluid production, etc. A few examples of faulted reservoirs are studied and discussed with the aid of a poroelastic finite element (FE) model specifically designed to address the fault mechanics over the macro-scale of interest. The results, although preliminary, provide a useful indication as to where and how fault activation can influence magnitude and extent of the land subsidence bowl above producing gas/oil reservoirs and point to a limited influence of the faults on the main occurrence.

Parallel computing is gradually becoming a main stream tool in geotechnical simulations. The need for high fidelity and for modeling of fairly large 3-dimensional (3D) spatial configurations is motivating this direction of research. A new program ParCYCLIC for seismic geotechnical applications has been developed. Salient characteristics of the employed parallel sparse solver will be presented. Using this code, simulations of seismically-induced liquefaction, lateral-spreading, and countermeasures will be presented and discussed.

Computational efficiency is of critical importance in the application of large-scale finite element simulations for solving complex geotechnical problems. This paper summarizes the formulation and implementation of a FETI domain decomposition technique for parallel finite element computations, highlighting the parallel efficiency and scalability of the software using a cluster of 16 interconnected commodity computers. The program is then used to simulate ground movements caused by the construction of a shallow cavern for a new subway station using a stacked-drift tunneling method which involved hand-excavation of a sequence of 15, 3m-square-section drifts through weathered alluvial soils.

Full 3D finite element modelling is increasingly used as risk assessment tool to evaluate complex construction process in major infrastructure project. This paper describes the use of a complex large scale, non-linear, 3D finite element model to evaluate construction related ground movements at the Grade I listed St Pancras Station for the Channel Tunnel Rail Link (CTRL) project in London. Details of the non linear soil and structural models are described. The assessment provided engineers responsible for the project significant insight into the behaviour of the sensitive structure and an understanding of the construction risks associated with deep excavations at the station site.

We present a computational framework that can be used to support and simplify the effort to convert an existing finite element program to run in parallel. The framework provides the programming foundation upon which the core finite element algorithms can run in parallel using much of the existing legacy serial code. We present results for nonlinear analyses of soil dynamics and reinforced concrete modeling using the TeraGrande and TeraScale_Dysac finite element applications, both built upon the parallel framework. The highly nonlinear and inherently multi-physics aspects of these analyses will be used to illustrate the features of the computational framework.

Unsaturated soils are three-phase porous media consisting of a solid skeleton, pore liquid and pore gas. The overall behavior of unsaturated soils is influenced not only by these three bulk phases, but also by the interfaces between them. Solution of coupled equations governing the dynamic behavior of unsaturated soils requires large amount of computational resources. A framework-based approach can be used to develop an efficient parallel finite element code for solving such large problems. Simulation of an unsaturated soil embankment subjected to earthquake loading is presented to show the capabilities of a framework-based computer code developed called TeraScale_Dysac.

This paper deals with numerical simulations of ductile folding of sedimentary rock layers with kilometer-scale dimensions. We use nonlinear continuum mechanics and the finite element method to understand the mechanics of large deformation leading to strain localization. Rock layers are subjected to combined bending and either extension or compression. Depending on the nature of the accompanying lateral deformation (i.e., whether it is extension or compression), localized deformation can manifest itself at different scales in the deforming mass. These studies are useful for integrating the mechanical and geological concepts and principles in order to formulate models constrained by available geological data.

The finite element discretization of time-dependent Biot's coupled consolidation equations typically gives rise to large symmetric indefinite linear systems. This paper reviews several symmetric indefinite preconditioners developed recently which can be used in conjunction with symmetric iterative methods such as SQMR or PCG. A numerical example shows that SQMR methods preconditioned by the proposed preconditioners are significantly more efficient time-wise than direct solution methods such as multifrontal solver (MA47, HSL2000) for large-scale symmetric indefinite linear systems.

Finite element analyses of the construction of supported excavations are simplifications of the actual process. Issues related to geometry, the support system details, constitutive representation of the soil response and the construction process dictate the use of such simplifications. While many of these factors remain beyond current numerical capabilities, three-dimensional finite element analysis can be effectively used to simulate actual excavation sequences. This is illustrated by analysis of the excavation for the Ford Engineering Design Center in Evanston, IL. Observed lateral movements and strut loads at this site are compared with results of three-dimensional finite element simulations of the design and actual excavation procedures to illustrate the method's applicability.

Large scale simulations with discrete element method (DEM) are often computationally expensive. A variety of approaches are used to address this persistent challenge by developing more efficient computational algorithms or improving employed computing hardware. In this article we propose to take advantage of parallel computation combined with the application of reconfigurable hardware. This is done by (a) employing multi-threads/processors to run the code on massively parallel machines, (b) exploring the placement of time-consuming parts of the DEM code onto field programmable gate arrays (FPGA) for further gains in speed.

Practical reliability procedures are illustrated for several common geotechnical engineering problems. Sensitivity information from reliability analysis is discussed and compared with other approaches. Specifically, reliability-based designs with respect to ultimate limit states are illustrated for a shallow foundation and an anchored sheet pile wall; reliability analysis with respect to serviceability limit states is illustrated for a laterally loaded pile incorporating one-dimensional random field. Comparisons are made with design based on partial factors and with Monte Carlo simulations.

Liquefaction of loose cohesionless soils can have detrimental effects on the stability of ground. The residual or liquefied strength of liquefiable soils is an important parameter when evaluating stability. Current procedures for estimating the liquefied strength are based on laboratory testing or from back-analysis of failures. Available procedures utilize deterministic methods for estimating the liquefied strength. This study presents procedures for assessing the liquefied strength within a probabilistic framework. Slope stability procedures using Monte Carlo Simulations are developed for the back-analysis. An existing liquefied shear strength relationship is then analyzed with the Hasofer-Lind Reliability Index method and several failures.

The paper describes probabilistic analyses in geotechnical engineering which use the Random Finite Element Method (RFEM). The method rigorously includes the influence of spatially variable soil properties on design outcomes relating to familiar geotechnical analyses such as bearing capacity, slope stability and limiting earth pressure. Two important observations from these studies are highlighted: Firstly, by making no a priori assumptions about the shape or location of the critical failure mechanism, the RFEM allows the mechanism to "seek out" the critical path through the soil. Secondly, the analyses indicate that there is a critical spatial correlation length that leads to a minimum strength of the soil mass.

The concept of autocorrelation is central to geostatistics and other stochastic representations of the spatial variability of soil properties, but little has been made in the literature about the practical implications of such spatial correlation for design. Much of the literature focuses on abstract statistical methods and theoretical modeling. However, analytical and field research over many years has demonstrated that spatial correlation dramatically affects the performance of earth structures and foundations, and in particular sheds light on aspects of geotechnical performance that are otherwise difficult to predict. Examples include differential movements, size effects, and extent of failures. Spatial correlation also has important implications for the selection of engineering design parameters from field test data and measurements. All of these things have practical usefulness in day-by-day practice and provide new insights into the behavior of facilities built on or in the ground.

Compared to conventional empirical methods to perfrom load displacement analysis, it appears beneficial to utilize a procedure that can explicitly consider the soil-structure interaction in the model development. To that end, this paper utilizes the "t-z" method for load displacement analysis of drilled shafts, which models the soil resistance along the length and at the tip of the drilled shaft as a series of springs. For non-linear soil springs, the governing differential equation that describes the soil-structure interaction may be discretized into a set of algebraic equations based upon finite difference methods. This system of algebraic equations can be solved to determine the load-displacement behavior of the drilled shaft when subjected to compression or pullout. This finite difference technique for analyzing non-linear drilled shaft load-displacement behavior can be beneficial for design of drilled shafts at the service limit state. By combining this technique with the Monte Carlo simulation method probabilistic relationships for drilled shaft design may be obtained.

This paper presents the framework, flow, and application of a probabilistic analysis system for determining internal/interface shear strength based on more than 500 direct shear test results conducted by Golder Associates over the last 9 years. The tests cover a large range of shear rates from 0.002 in/min to 0.5 in/min, different normal stresses up to 43,200 psf, and various types of internal/interfaces, including geomembrane versus soil, geomembrane versus geotextile, geomembrane versus geosynthetic clay liner, etc. Using statistical analysis and probabilistic methods, the system allows engineers to determine shear strength parameters based on different groups of direct shear tests results. If properly applied, the system can be very useful in helping engineers select proper shear strength parameters, especially when facing the challenge of limited budgets and test results.

Calibrations for reliability-based design (RBD) of foundations are critical but are largely "invisible". Some key methods of calibration are discussed, including issues ranging from the basic assumptions involved, distributions of key variables, uncertainties in both load and resistance, target reliability, etc. The goal is to assist engineers in understanding the level of sophistication, or lack thereof, in different approaches to calibrations, which then translates into the degree of confidence one can have in a particular calibration or code.

Soil liquefaction phenomenon involves progressive intergrain contact deformation, slip, reorganization of contacts, and eventual collapse of soil skeleton. During the process leading to liquefaction energy is continuously lost mainly along frictional contacts. This paper presents a theoretical framework for estimating the frictional energy loss along contacts. A pore pressure model is presented as a function of dissipated energy. Based on above developments and understanding, a numerical simulation model using finite difference method is developed to simulate energy dissipation, pore pressure generation, pore pressure dissipation, and densification in a given soil profile for a given earthquake motion. The results are compared with data from centrifuge model tests.

Recent evidence indicates that partially saturated conditions may exist below ground water level. Laboratory test data have shown that the seismic resistance of sands to liquefaction increases as saturation decreases. This paper presents the results of an investigation on partial saturation effects on liquefiable ground response. Using a coupled stress-flow dynamic analysis procedure the ground response to seismic shaking has been analyzed in terms of excess pore pressure and deformations. The results indicate that displacements of a slope under partial saturation condition can be larger than that of fully saturated conditions when a low permeability sub-layer is present.

The earthquake induced ground motions are transient and nonstationary. Both their amplitude and frequency content vary with time. Analysis and design of structures need to consider these nonstationary characteristics. In studying time series, several methods have been developed and used by researchers and practitioners. Here, a comparison of Fourier Transform (FT), Short Time Fourier Transform (STFT), Hilbert Huang Transform (HHT), and Wavelet Transform (WT) are presented.

A fully coupled continuum-discrete hydromechanical model is employed to analyze the response of saturated granular deposits to multi-direction dynamic excitations. The (per unit of volume) kinetic energy of the input motion is used as a new metric to assess the liquefaction potential under such excitations. Numerical simulations were conducted to assess the validity of this new metric and the impact of multiple direction excitations. These simulations showed that the liquefaction of level ground deposits is highly dependent on the amount of input energy. Nearly identical rates of pore pressure build-up were obtained when a deposit was subjected to one- or two-direction excitations with equal kinetic input energy.

Finite element analyses of several seismically- and dynamically-induced liquefaction flow failures suggest that existing relations to estimate the yield strength ratio of contractive, saturated sandy soils may be overly conservative. Herein, we propose tentative revised relations for estimating yield strength ratio using normalized penetration resistance. These relations are based on available laboratory data from triaxial compression, torsional shear/triaxial compression, direct sample shear, and ring shear tests on isotropically- and anisotropically-consolidated specimens. We use the finite element analysis results from the case histories for preliminary verification of the proposed relations for yield strength ratio.

Seismic waves experience changes in the wave length when they propagate through the soil generating changes in the propagation velocity. On the other hand, the experimental evidence shows that the soil also presents a variable stiffness under dynamic loads like the produced ones by earthquakes. These effects take place by the non-linear soil behavior and are bound to phenomena like dissipation, dispersion, isotropization and liquefaction. The hypoplastic constitutive model is able to reproduce the non-linear soil behavior and therefore, effects and phenomena related to this behavior. The mentioned effects and phenomena are reproduced using hypoplastic simulations of the soil behavior.

This paper presents a micro-mechanical study of the dynamic response of unsaturated granular soil deposits when subjected to dynamic excitations. The discrete element method was used to idealize the soil skeleton. Suction forces were modeled using interparticle water bridges in pendular state. Numerical simulations were conducted to investigate the impact of moisture content on the dynamic response of level grounds. The outcome of these simulations provided a valuable insight into the response mechanisms of unsaturated soils.

WebShake (Prototype Engineering, 2004) is a user-friendly web implementation of SHAKE91. The program uses Microsoft .NET technology to create an Internet-based application. Data entry and validation are done as a Windows desktop application. WebShake is run by sending the data to the .NET WebService. The results are returned through the Internet and saved to the desktop of the local user of the program. The application can be modified to store any desired data, including user identification, billing information, and statistics of analysis runs. The web application raises a number of issues that have existed since 1960s.

In this study, the impact of explosions on underground facilities is evaluated through numerical analysis, considering key factors including charge weights, size and shape of the tunnel, standoff distance (a distance from the detonation point to the tunnel wall), and various types of surrounding ground. Proposed explosion wave parameters and tunnel damage assessment charts are developed from the numerical analysis and provide a methodology for simple and practical application to vulnerability assessment of tunnels.

Probabilistic methods to predict explosive effects against underground structures have traditionally been concerned primarily with site characterization uncertainties such as rock layering and rock property variability. However, uncertainty in the predictive models themselves can have an equal or greater impact on the probability of structural collapse. Uncertainties were quantified for equations used to predict the effectiveness of explosive penetrators, by comparing the engineering models to test data in which the rock properties were measured. The engineering model uncertainties were incorporated into probabilistic explosive effects software along with a confidence-based convergence algorithm that determines when sufficient simulations have been performed in order to confidently know the distribution of possible outcomes. The influence of engineering model uncertainties is demonstrated by simulating an explosive event against a highway tunnel facility. The predicted outcome (including expected rubble volume and the probability of catastrophic failure) is compared for simulations that incorporate only uncertainties in rock layering and rock properties, and simulations that incorporate engineering model uncertainties in addition to site characterization uncertainties.

The effects of surface explosions on underground structures were studied through physical modeling, utilizing a geotechnical centrifuge. The types of structures considered in this study include tunnels and pipelines, located relatively close to the ground surface (within 5 m below ground surface). The use of the geotechnical centrifuge allows one to study the effects of large explosions on prototype scale, by using smaller explosives and scaled models of actual structures. This is explained by the centrifuge scaling law which states that the effects of an explosion will scale to the third power of the centrifuge acceleration (g) level. Controlled explosions were conducted in centrifuge experiments under 70 g gravity and strain measurements were recorded at different locations of the underground structures. The results of these experiments can be useful in designing new underground structures as well as for developing protective retrofits for existing structures. The influence of a compressible inclusion barrier immediately outside the structure was also studied. Depending on the thickness of cover between the source of explosion and the structure, the presence of the barrier may have a beneficial effect in reducing the impact of the blast.

Implementation of a 2D groundshock algorithm with a 3D visualization application provides a unified solution for determining the effects of explosives on underground facilities. Physics-based explosive effects calculations are performed on models to access groundshock environment and corresponding structural response. Groundshock peak stress, strain, and velocity iso-contours are calculated from the resulting 2D FEA and displayed by sweeping the results in 3D about the localized surface normal. The groundshock environment is used to predict the probability of severe damage at points of interest within the facility model. Three dimensional results are displayed in ghost, cutaway, and wireframe rendering modes.

This paper compares the full scale test response of buried reinforced concrete walls loaded by an externally buried, cylindrical cased explosive threat with FLEX/FUSE coupled nonlinear code computations. FLEX is a nonlinear, large deformation finite element structural code. FUSE is a total Lagrangian large deformation, explicit code that represents solid as well as fluid behavior. The threat was placed at various standoffs from the walls and two orientations to provide a wide range of damage. The walls were instrumented with accelerometers, displacement gages, and pressure transducers. Free field soil pressure transducers were also included. The FLEX/FUSE results and test gage data are compared.

A Pile-Raft has been in use for the foundations of buildings and bridges. The load in the structure is transferred to the soil not only by the interaction between the soil and the piles but also by the interaction between the soil and the slab. The analysis of this unique foundation is very challenging because of the complexity involved in the interaction between the soil, the piles and the slab. An elastic three dimensional finite element analysis was proposed for the analysis of this type of foundation. The elastic analysis can provide a good estimation of load transfer levels between the different components of the foundation; however, because of the nonlinear behavior of the soil, the estimation of the foundation capacity may not be as accurate. Therefore, in order to have a better estimation of the foundation capacity for even small level of deformations, a non-linear analysis is recommended. The current paper is aimed to discuss the nonlinear analysis of pile raft foundation systems. A general finite element program, AMPS, is used to perform the analysis. A suitable nonlinear model is used to model the soil behavior, and contact interfaces are included to study the interaction between the soil and the piles and between the soil and the slab. Two pile-raft foundations were analyzed using the FEM program.

Monopiles for offshore wind energy converters are highly laterally loaded structures with diameters up to 6 m and more. Their design is based on the well-known p-y-method, which has been calibrated on field test results for much smaller pile diameters. The present paper provides an FE-analysis of the monopile behavior compared to the standard design method. The results indicate the influence of the pile diameter on the pile-soil stiffness and point out that the p-y-method overestimates the soil stiffness at great depth. A modification of the p-y-method is proposed which better accounts for the pile-soil interaction of large diameter monopiles.

Analytical solutions have recently been developed for analyzing the behavior of piles in a group subjected to loading in three-dimensional space. The piles may be installed vertically or on a batter and their heads may be fixed, pinned, or elastically restrained by a rigid pile cap. The several components of the analytical method have been coded and iteration is used to accommodate the nonlinear response of the soil around each pile in a group. With availability of a rational and convenient tool, the engineer may consider several alternatives in a design, including pile spacing, batter angle, and type of pile. This paper presents an example of use of the analytical tool to study the behavior of a large group of piles.

In the scope of this paper one case history of a piled raft foundation, Messeturm tower in Frankfurt Germany, has been studied using a viscohypoplastic constitutive law in a three dimensional finite element analysis with the program ABAQUS and the user subroutine UMAT developed by A. Niemunis and the geotechnical group of the Karlsruhe university in Germany. In the finite element analysis the construction process of the Messeturm tower is modelled. The calculated results will be compared with the in situ measurements with the purpose to verify the viscohypoplastic law in a boundary value problem.

This paper focuses on the behavior of micropiles group under seismic loading. A three-dimensional finite-difference analysis in the time domain is carried out to investigate the effects of soil nonlinearity and sliding at the micropile-soil interface on the seismic response of a micropiles group. Proper boundary conditions are used to simulate radiation effects of infinite half space. The study shows that the nonlinearities of the soil and micropile-soil interface both have significant effect on the seismic response of the micropiles group as well as that of structure.

The "El Buey" dam is located at 45Km of Medellin in the NW of Colombia, placed in an area of high seismic activity. This dam is part of the main water supply system of the city. The "Study of seismic vulnerability of El Buey dam", was developed and included analysis of instrumentation records, local geological study, seismic hazard evaluation with EZ-FRISK v6.2 software and subsoil exploration. Static and dynamic laboratory test and numeric analysis were made for evaluation of seismic response of the dam with QUAD4M and PLAXIS V8.1. In this paper, a summary of the executed activities is presented.

A dynamic numerical modeling analysis was performed to evaluate an innovative remediation design on a series of high hazard earth dams, located in the Pacific Northwest. The initial seismic evaluations indicated that the dams would likely fail due to liquefaction, and required remediation. An seismic mitigation buttress design was selected to confine the liquefiable soil on the downstream side of the dams, and allowing the upstream slopes to deform during the earthquake. However, the challenge was to design to a level of confidence that the amount of upstream deformation would remain within tolerable limits so that the dams would not fail. With the aid of FLAC program, an dynamic numerical modeling analysis was performed to evaluate the buttress and the upstream slope deformation by simulating the design earthquake and applying a soil liquefaction dynamic model. A comparison study was made between the FLAC analysis and the simplified approaches.

A setback levee is being considered as a construction alternative to mitigate erosion occurring along the Sacramento River in Sacramento, California. Current standards require levees to meet certain criteria set by US Army Corps of Engineers (USACE) and Federal Emergency Management Agency (FEMA). Among other requirements, these standard criteria include performing a slope stability analysis to ensure safety of the levee due to water level fluctuation and seismic loading. Accordingly, this paper presents the details of two dimensional slope stability analysis for the proposed setback levee. Due to the lack of nearby suitable fill materials the stability analysis illustrated how using different levee materials in combination with varying the levee geometry can result in stability of the levee being acceptable.

At the present time it is built in Cartagena-Colombia, a perimetral road bordering La Virgin's Marsh, where the subsoil is shaped for deposits of silty organic clays of very low shearing resistance and high compressibility, which it makes difficult the implantation of some structure on them. The conformation of road required the construction of embankments of confining and filling among themselves with material of dredging of the marsh's bottom. In order to explain the large deformations and crackings of the trial embankments constructed initially, were modeled by finite elements each join of stages of constructive process determining pressures of pores, stress and deformations to establish the interaction among the embankments, the filling and the ground foundation. By means of the information of settlement's plates installed at the trial embankments and theoretic behaviour models for soft soils, were determined the deformations generated by consolidation of the subsoil deposits with the aim to evaluate the stability and functionality of long-term road themselves. Finally, the results of different models used on are compared and then sensitivity analysis of them are taking to account some possible variations in the resistance properties of the ground foundation. The effect of seismic movements was determined starting from two-dimensional methods of propagation of wave (program QUAD4M), to evaluate the cutting stress and deformations induced by the seism at the soft soils of the foundation and the embankments and fill of project. Recommendations to avoid the cracking of the embankments and to guarantee the stability and functionality of the road. The measured suggested include the improvement of the subsoil by preload and vertical drains, the reinforcing of the embankment with geosintetics and the drainage of the fill with sinks of gravel.

Geosynthetic reinforced soil (GRS) walls have become an important applications of retaining structures in earthquake Asia areas such as Taiwan and Japan. In this paper, the authors first present a numerical model that is capable of simulating dynamic response of GRS slopes. Shaking table results were studied in developing the model. An updated model, "rigid cable box" model, is then developed to simulate GRS wall. Also a selected GRS wall case, that failed during the 921-Chi-Chi earthquake, is then studied with the developed model and real earthquake records in an effort to observe seismic performance of GRS walls. Conclusions and discussion of this paper are hoped to be helpful to the seismic design of GRS walls.

Widening of a highway embankment may increase loads acting on the weaker portions of the culvert. To accommodate increased loading, geofoam will be placed above the weaker portions of the culvert. Numerical analysis using FLAC was performed to predict loads on the culvert. Results of the analysis show that geofoam significantly reduces maximum moments on top and bottom of the culvert. The moment reduction is a function of the size of geofoam and the distance between top of culvert and the geofoam. By considering these factors, effectual curves are obtained from the numerical analysis.

This paper presents a case study in which both limit equilibrium and numerical methods were used in slope stability analyses during design of a landfill closure. The limit equilibrium method was initially used to provide a quick assessment of the site and identify critical slopes with marginal factors of safety for further analysis using numerical modeling. Further, the paper presents differences between the two methods in their ability to predict the factor of safety and the use of the numerical modeling approach to evaluate several methods to stabilize the slopes.

This paper illustrates how water-balance predictions for alternative covers using two unsaturated flow models (VADOSE/W and UNSAT-H) are affected by three factors: (i) the function used to describe the soil-water characteristic curve and the unsaturated hydraulic conductivity function (k-function), (ii) the shape of the k-function, and the (iii) lower boundary condition used in the simulations. Field data from two alternative covers are used for comparison. Each factor is shown to have a marked effect on water-balance predictions, even though the same input data are used in each case. The findings suggest the need to identify the options and parameters that are most appropriate when simulating alternative covers.

There are thousands of old unlined landfills and industrial waste sites in the U.S. where ground water is impacted. In this paper we have presented a relatively new technology called reactive permeable blankets that can be used to cleanup the ground water or leachate. This technology could be relatively cheaper and would offer faster cleanup time compared to conventional passive vertical permeable reactive barriers. The permeable blanket technology has been field tested for leachate recirculation in municipal solid waste (MSW) landfills. In this paper we have presented the conceptual model to implement this technology as an active remediation method for old landfills or other industrial sites.

Loading sequences affect the shape of settlement-time (s-t) curves in embankment engineering. Based on the rheological stress-strain relationship of soils, the characteristics of s-t curve of embankment settlements are analyzed under different loading sequences. The results indicate that the s-t curve is in exponential shape under instant loading, S-shape under linear loading. The prediction models for the above two different loading sequences are presented respectively. All predicted results show that it is logical and significative to predict embankment settlements under different loading sequences with different models.

This paper presents the use of a FEM simulation technique to predict the long-term behavior of an abutment slope in the area of the Cuyahoga 90 Central Viaduct Bridge that was previously stabilized with the structure elements of drilled shafts and rock anchors. Monitoring of the sensors (strain gages, load cells, and inclinometer casings) provided baseline data for calibrating the soil parameters. FEM predictions of the future 75 years slope behavior help highway agency to determine proper course of action for the planned bridge expansion project.

Artificial neural networks (ANNs) were used in this paper to develop an improved and more accurate approach for backcalculating pavement layer moduli from Falling Weight Deflectometer (FWD) test data collected in the field. For this purpose, critical pavement responses were computed by the ILLI-PAVE finite element program widely used and proven to be effective for the analysis of flexible pavement systems with the considerations of the nonlinear aggregate base and subgrade soil behavior. The ANN models were then trained to map the nonlinear functional relationships between the FWD deflections, layer properties, and the critical pavement responses.

Triaxial tests are very useful to determine the mechanical characteristics of unbound base mate-rials under monotonic and repeated loads. Unfortunately large triaxial specimens are required to test 0/40 mm sized aggregates and this makes the practical use of triaxial tests cumbersome. Using the results of a large number of test results, equations have therefore been developed that allow the resilient and permanent deformation characteristics to be estimated from physical parameters like gradation, degree of compaction etc. This paper describes briefly the test program as was carried out as well as the predictive equations that have been developed.

This paper presents the use of hypoplastic constitutive model for the analysis of unbound granular layers in flexible pavement structures. The hypoplastic model predicts the experimentally demonstrated non-linear behavior in granular materials, considers initial conditions, and doesn't make use of the classic elements of the elastoplasticity. In addition, the paper presents the results from numerical simulation of a flexible pavement structure. The granular layers were modeled by using the elastic and hypoplastic theories. The stresses and strains in a granular material may be underestimated when using elastic models.

External pressures applied to a saturated pavement pore structure are often dynamic due to the repeated tire loading. Therefore, a dynamic permeability constant is more realistic representation of the response of a pavement pore structure than the Darcy's permeability. To investigate the unsteady (dynamic) fluid flow in asphalt pavements, a 3D fluid flow model was developed using the lattice Boltzmann (LB) method. The model was validated using the well-known closed form solution of oscillating flow through a circular tube. A number of simulations were carried out to calculate the dynamic permeabilities of different asphalt specimens exposed to pulsatile pressures. It was shown that the dynamic permeability of an asphalt pore structure collapse on a single curve for a given frequency, confirming its universal behavior.

In this contribution, a contact interface element based on the earlier work of Swoboda is presented. A no-overlap condition, friction, bonding and de-bonding are implemented by the Lagrange multiplier method with contact stresses as multipliers. Several implementation issues will be addressed. Finally to demonstrate the capabilities of the contact element a 4-point shear test simulation is shown.

Finite element analyses were conducted on pavement sections to assess the benefits of reinforcing the base course layer with geogrids, and to evaluate the effects of subgrade strength, thickness of the base course layer, and geogrid stiffness on these benefits. The benefits were defined in terms of the surface permanent deformation. The results showed that the benefits found in pavement sections on weak subgrades were always superior to those found in pavement sections on stiff subgrades. In addition, the benefits of the inclusion of one geosynthetic layer at the optimum location were reduced as the thickness of the base course layer increased; while they were enhanced with increasing the stiffness of the geosynthetic material.

Accurate evaluation of subgrade resilient modulus (M_R) is important for effective and economical design of flexible pavements. Resilient modulus of subgrade soil is the elastic modulus based on the recoverable strain under repeated loads and depends on several factors like soil properties, soil type, and stress states. This paper presents prediction equations to estimate M_R from a set of soil physical properties for 3 AASHTO subgrade soil types, namely A-1-b, A-3, and A-7-6. The prediction models were developed using the multiple linear regression analysis of the data extracted from Long Term Pavement Performance Information Management System (LTPP IMS) Database for 82 test specimens, approximately 1230 M_R values, from 16 states in New England and nearby regions in the U.S. and 1 province in Canada. Generalized constitutive model consisting bulk stress and octahedral shear stress was used to predict M_R of subgrade soils by developing regression equations for the k-coefficients that relate these coefficients to various soil properties, e.g. particle size, moisture contents, densities, and Atterberg limits. The R² values obtained for the prediction equations for k coefficients relating to the soil properties range from 0.45 to 0.79. To verify the prediction models independently, laboratory M_R tests were conducted on a few New England subgrade soils. It was observed that the predicted M_R values compared well with the laboratory measured values for A-1-b soil samples. However, because of some soil property values being outside the range used in the development of the prediction models, the comparison was poor for A-3 soil samples, and for A-7-6 soil, M_R values could not be predicted due to negative values for k₂ coefficient.

A finite element model was developed for flexible pavements, and will be implemented to analyze data acquired from seventeen heavily instrumented test sections, reinforced with geosynthetics. The model will enable the prediction of critical stresses and strains as a result of vehicular loads. The significance of the methodology and supporting variables, methods, and models selected to complete the modeling approach will be the focus of this paper. More specifically, the type of model, selection of model parameters, choice of material models, and testing scheme developed to provide material properties will be described in detail.

The mathematical structure of a triaxial, strain rate sensitive, history and temperature dependent constitutive model for asphaltic concrete is presented. By postulating a multiplicative decomposition of the deformation gradient and an additive decomposition of the Helmholtz free energy function, an elegant formulation is obtained for the three dimensional elasto-visco-plastic response of the material. An operator splitting methodology has been utilized for formulation of efficient computational algorithms for integration of the local evolution equations. Explicit procedures have been also formulated for the experimental determination of the model parameters. Results of the utilization of the model for the investigation of the non-linear response of asphalt concrete specimens are reviewed in the last part of this contribution.

This paper explores new methods that can reduce pavement preservation costs by incorporating information technology. One way to reduce costs and improve efficiency is to group adjacent pavement projects into a single let project composed of a series of pavement segments, each segment being equal to or less than 1 mile. If distresses vary from location to location and can be grouped into sub-projects that have uniform distress conditions, a more appropriate rehabilitation treatment method can be used for each sub-project instead of a single, more costly treatment for the entire project. This paper presents a spatial search algorithm using fuzzy c-mean clustering to determine the most economical let project termini by minimizing the pavement condition variations in each let project while being subject to the constraints of minimal project scope (i.e. length), cost and barriers, such as bridges. This paper presents preliminary results using hypothetical highway pavement condition data to demonstrate the capability of the developed algorithm. The benefits of using the developed algorithm are summarized, and recommendations for future research are discussed.

Inverse analysis techniques can be used to calibrate finite element models of the construction of deep, supported excavations. If field observations are collected and transmitted to a host computer in real time, then these techniques allow one to update predictions of performance quickly enough to be of use to contractors and engineers responsible for the design and construction of the project. This paper presents procedures showing how both lateral movements measured by inclinometers, settlements and loads in support elements can be incorporated into such analyses. Results of simulations of synthetic excavations are presented to show how the sensitivity of the calibration varies as a function of the type of observation employed and how the sensitivity is increased when displacement and strut load data are used together as observations in the inverse analysis.

The deformations of underground structures during seismic events are largely determined by the relative stiffness between the structure and the surrounding ground. A new analytical solution has been developed to estimate the deformations of buried structures. Soils exhibit a marked non-linear hysteretic behavior with cycles of loading. Such behavior can be incorporated into the analysis by an iterative scheme where the soils' shear stiffness is reduced with the structure's deformations. Initial verification of the method is done by comparing its predictions with those from a dynamic numerical analysis of the failure of the Daikai station in Kobe during the 1995 earthquake.

A temporary excavation support system was installed for construction of a footing along a 45° site slope for a five-story parking garage at George Mason University in Fairfax, Virginia. This paper evaluates the performance of the temporary excavation support system for this project. The site is located within Piedmont Physiographic Province and is underlain by undocumented fill, residual soil, and disintegrated rock. The residual soils predominantly consist of fine sandy silts and silty fine sands with mica. The computer programs "ct-Shoring" and PLAXIS were used for the analyses and design of the temporary excavation support system. An 8.5-ft tall cantilever soldier pile wall was used to support the 15-ft high 45° site slope at the back of the wall. The maximum deflection for the cantilever wall was estimated to be less than 1.5 inches based on the analyses and design and construction considerations. The observed final wall deflection was less than 1.5 inches.

The network of channels called Navigli was built in the surrounding country and downtown Milan, Italy. Wave propagation measurements were taken along the channel for a total length of 80 m. Each test consisted of the simultaneous measurement of the response of the wall with 15 transducers to an impulse load. The relative condition of the wall is evaluated by considering three main wave characteristics: group velocity, phase velocity, and attenuation coefficient. A fuzzy logic model is developed to make a relative evaluation of the condition of the sidewall.

Ground movement control for protection of existing structures and facilities is an increasingly important aspect of design and construction. Advances in soil-structure interaction modeling and in construction techniques allow more sophisticated prediction and control of ground movements. This paper discuss a comprehensive approach, which we call M³, that includes modeling, monitoring, and managing the below ground construction to achieve the desired movement control. We present two case histories that illustrate this approach, one where very stringent control of movement was required to protect the historic U.S. Capitol building, and one where massive jacking pit headwalls needed to accommodate up to 14 inches of lateral ground movement due to ground freezing.

Conventionally highway bridge abutments are supported on deep foundations. As an embankment approach settles, it results in a differential settlement between the approach pavement and bridge deck, which causes the traveling vehicle to experience an impact force. This phenomenon is called "bridge bump." A mechanically stabilized earth bridge abutment (MSE abutment) minimizes the damaging and unpleasant bridge bump by eliminating the differential settlement. This article reports the result of a series of 3-D nonlinear finite element analyses to investigate the performance of MSE bridge abutments supported on a U-shaped MSE Wall (UMSEW). Overall structural integrity, sufficient clearance, smooth transition from pavement to bridge deck and pleasing aesthetic appearance are critical long-term performance requirements of an MSE abutment. Three MSE abutments supporting a bridge with single span length of 48 m (160 ft) and three different footing sizes (2.17 m, 3.05 m, and 3.96 m), respectively were analyzed for the lateral deformation, vertical settlement, earth pressure, inclusion stresses, and bearing pressure underneath the footing. The analysis results show that, when founded on a sound subsoil or rock, the UMSEW effectively supports the MSE bridge abutment.

This paper presents a portion of an extensive model calibration for a finite element analysis of a mechanically stabilized earth wall located along the I-15 reconstruction project through Salt Lake City, Utah. The 9.1 m wall was constructed on a soft clay foundation, and instrumentation was placed in this material to monitor foundation response. Vertical movement at the base of the wall was 0.5 m at the end of primary consolidation, and vertical deformations were obtained throughout the soil profile. These readings provided the data used to calibrate a finite element model of the MSE wall using Plaxis software.

Internal bracing in conventional 2-d finite element models of deep excavations is modeled by averaging the stiffness of the internal braces over their spacing and considering the bending stiffness of the wall about its neutral axis in the plane of bending. The effects of the waler connecting the brace and wall are usually ignored. When making a 3-d simulation, each internal brace can be modeled individually. In this case, when evaluating the 3-d distribution of ground movements and structural responses, the effects of the waler should be considered. However, it is not feasible to explicitly model each waler and all the connections between the brace, waler and wall. This paper summarizes the considerations related to such simulations, presents the results of parametric studies that show the effects of sheeting flexibility parallel to the wall and compares results of 3-d finite element simulations to responses at the Ford Design Center excavation in Evanston, IL.

With various two-dimensional (2D) and now three-dimensional (3D) seepage analysis programs available it is important to understand how results from 2D and 3D models compare and when a 3D analysis may be warranted. This paper compares the results of SEEP/W© and Seep3D© software programs developed by Geo-Slope International. The project analyzed is a proposed excavation near the landside toe of the Sacramento River levee in Sacramento, California. Based on historical underseepage and through seepage emanating from this area during periods of high river stage, a seepage analysis was required by the City Building Department. The results of a 2D and 3D analysis were compared for an infinitely long excavation to calibrate the 3D model and then a limited excavation was modeled in 3D. This comparison revealed calculated seepage exit gradients 50% larger using the 3D model compared to the 2D model results.

Construction of an underground extension required deep excavations immediately adjacent to the Virginia State Capitol building. Historic preservation required extraordinarily limiting movement criteria for the building protection. To confirm that such movements could be attained, and to establish design and construction requirements, numerical modeling was performed using FLAC and PLAXIS. Results indicated that the desired movement criteria were generally achievable. Contingency steps were put in place as mitigating measures in case of excessive movements. With the excavation complete, recorded movements are well below those estimated. The project success is attributed to detailed design, redundancy in construction, close cooperation among parties, and real-time monitoring by geotechnical instruments.

A 2-D model which accounts for the effect of coupled sliding and rocking motion and uses strain dependent soil stiffness and material damping for calculating the response of rigid retaining walls subjected to dynamic loads, was developed earlier. This model was used to study the effect inclination of the wall face in contact with the backfill, on its displacement under the effect of ground motions due to Northridge, ElCentro and Loma Prieta earthquakes. The effect of wall inclination on cumulative displacements is discussed and its role in achieving possible cost effectiveness in design of rigid retaining wall is highlighted.

Geotextile reinforced embankment constructed over deep mixed soil columns was analyzed for settlements using a finite element based Plaxis program. The embankment over treated soft clay was considered as two-dimensional plane strain problem. Soil materials were modeled as a linearly elastic perfectly plastic material following Mohr Coulomb failure criteria. Average settlement under the embankment was also estimated using a simplified analytical procedure. Predicted settlement results from finite element software, analytical procedure and available literature models were presented in this paper along with measured values. Comparison of above results showed that the numerical FEM program Plaxis predicted settlements that are close to the measured settlements. Variations among the methods predictions and possible reasons for these variations are explained.

Deep mixed (DM) columns have been commonly used to increase bearing capacity of soft soil and reduce total and differential settlements of embankments. In most analyses (especially numerical analyses) of embankments over DM columns, two-dimensional models are commonly used for simplicity. However, it is not clear how well the two-dimensional (2D) models represent the behavior of embankments over DM columns that are typically installed in a three-dimensional (3D) pattern, such as a square or triangular pattern. In this study, 2D and 3D numerical analyses were conducted to show the comparisons of their results including maximum settlements and vertical stresses. In the 2D analysis, individual DM columns and the soil between these columns are converted to several DM walls parallel to the centerline of the embankment. The DM walls are assumed to have equivalent moduli or strength averaged from the individual DM columns and the soil between these columns based on their areas and moduli or strengths. The comparisons show that the 2D model calculates slightly (conservatively) larger maximum settlements at the base of the embankment than the 3D model if the DM walls/columns are within the elastic limit. However, the 2D and 3D models produce very different results of vertical stresses on the top of DM walls/columns.

The finite element method (FEM) is growing in popularity over the pressure diagram/hand calculation method for analysis of excavation systems in general and deep soil mixing excavations in particular. In this paper, a finite element analysis is used to study the behavior of a deep mixed excavation. Through the use of Plaxis (a FEM software program), the construction sequence is simulated by following the various construction phases allowing for deflections due to strut or anchor installation to be predicted. The numerical model used in this study simulates the soil cement columns as a continuous wall matching the bending stiffness of the actual wall. Input parameters based on laboratory tests and modeling assumptions are discussed. An example of the approach is illustrated using the Islais Creek Transport/Storage Project in San Francisco, California.

Embankments constructed on soft soils that are improved with Deep Mixing Method (DMM) columns induce both vertical and lateral loading on the composite foundation. The interaction of embankments, soft soil, and DMM columns is complex, yet current design practice for DMM foundation systems is based on simplified deterministic evaluations of settlement and slope stability. Two shortcomings of this approach are that (1) the properties of DMM columns installed in the field are highly variably and (2) limit equilibrium does not capture all modes of failure. These shortcomings are addressed in practice by using judgment and knowledge of precedent. However, this approach has produced failures due to under-design and excess costs due to over-design. Reliability analyses can provide the design engineer with another useful tool for embankment design by incorporating the variability of DMM column strength and modulus. This paper presents reliability analyses of stability and settlement for an example embankment. In the case of slope stability, a combination of numerical analyses and reliability analyses is needed for a complete understanding of system behavior.

The Cement Deep Soil Mixing (CDSM) method was used for in-situ solidification of river sediments in Newark Bay, New Jersey. The objective was to evaluate the viability of CDSM for the in-situ solidification of river sediments. The results showed CDSM Slurry mixtures, as low as 7% in cement content, result in significant solidification and strength gain of in-situ underwater sediments under ambient river conditions. Therefore, as an alternative to dredging and removal, the contaminated solidified sediments could be left in-situ and properly capped. Also, Nominal resuspention of solids takes place due to some upward movement of mixing spoils but the extent is limited to 75 to 120 ft. from the treated zone.

The deep mixing method is widely applied in highway engineering for soft ground improvement. Deep mixed columns (DMCs) and surrounding clays consist of a composite foundation, but the change in strength behavior of surrounding clays due to the installation of DMCs is still not well understood. In this study, the cone penetration tests were performed to investigate the change in soil strength of surrounding clays after the DMC installation at different distance from the column border and time after the installation. Based on the tested data, the strength of surrounding soils is discussed.

For the construction of 14 cross passages connecting the twin tunnels of the Sophiaspoortunnel (The Netherlands), the Artificial Ground Freezing technique was applied as temporary soil improvement. AGF by Brine and Liquid Nitrogen was implemented. Automatic data acquisition and recording systems were installed to monitor the variation of the temperatures in the soil during the freezing intervention in order to control the behaviour and the efficacy of the treatment. The LN process was managed through an automatic system controlling the LN flow versus temperature and the shut-down of the supply in case of safety hazards inside the shafts.

The Alameda Corridor included a grade separation with mechanically stabilized earth (MSE) approach embankments 9.5 meters high located over loose potentially liquefiable and compressible soils. Because the site elevation was below sea level, relatively impervious vibro concrete columns (VCC) were used to avoid flooding. Also, because of the site's various and discontinuous layers of sandy and clayey soils, prescriptive ground improvement was selected. The designers were unaware of any experience with VCC in the Western United States or using VCC to reduce liquefaction potential.

In this contribution, by means of numerical investigation, two types of vertical drainage systems, for instance drainage strip, sand wall and their combination with applying under pressure will be examined. The influence of under pressure to the process of consolidation will be investigated. The findings of this contribution will provide the necessary information for improvement of existing designs of vertical drains and the development of design specifications.

Sand compaction pile (SCP) method is composed of compacted sand pile inserted into the soft clay deposit by displacement method. SCP-reinforced ground is composite soil which consists of the SCP and the surrounding soft soil. While a surcharge load is applied on composite ground, time-dependent behavior occurs in the soft soil due to consolidation according to radial flow toward SCP and the corresponding stress transfer also takes place between the SCP and the soft soil. This paper presents the numerical results of cylindrical composite ground to investigate consolidation characteristics and the stress transfer mechanism of composite ground reinforced by SCP under quaywall. The results show that the consolidation of soft clay gives a significant effect on the stress transfer mechanism and stress concentration ratio of composite ground.

A plain concrete pile was constructed to improve the soft soil for road bed and the construction garbage was used as the fill of subgrade. Deformation monitoring surveys were conducted and measurements of stresses were carried out throughout the construction process of filling subgrade. In order to determine design parameters for the construction garbage as fill, the soil-pile interaction was back analyzed using the finite element method. This paper describes the process of selection of material parameters through careful assessment of the laboratory data and the results of the numerical back analyses. Once selected, the parameters were verified on the other cross section of road and later used in routine design. Generally, a good agreement between predicted and observed behavior was achieved suggesting the adequate determination of the geotechnical model and the parameters of construction garbage.

When a bridge is constructed on soft ground, the ground may deform largely due to the weight of embankment. In order to prevent large ground deformation and lateral flow, air foamed lightweight geomaterial has been applied as backfill material behind bridge abutment. Bridge constructed on soft ground in Japan backfilled with the lightweight material is investigated in this research. 2D and 3D FE analysis had been carried out to evaluate lateral backfill pressure and deformation of abutment-backfill system. Results from FE analysis revealed that placing of elastic plate in backfill is effective method for reduction of lateral backfill pressure.

Finite element analyses demonstrated that a combination of jet grout block and slab was very effective in controlling inward wall displacements for bottom-up construction in soft clay. It is recognized that inward wall displacements prior to strut installation must be minimized for effective bracing. A jet grout block, formed along the retaining wall, that extends to a higher level above the jet grout slab allows the possibility of resisting inward wall displacements at the earlier stages of excavation. The jet grout elements also improved basal stability of the excavation by restricting heave close to the retaining wall.