FMGM 2007: Field Measurements in Geomechanics

The analysis of monitoring data is often aimed at deciding if some characteristics of the monitored structure have deteriorated or are going to worsen. To do this engineers use monitoring systems which are often highly instrumented but data are confounded by measurement errors and secondary effects. Therfore it is important first to separate the main signals which identify the health of the monitored structure and, second, to give a synthetic statistical description of the possibly many measurements obtained, which may be numerous. Along these lines, the paper proposes an integrated approach, coupling the monitoring system with a set of techniques for statistical surveillance and diagnostics, which give appropriate data understanding and rules for signalling that the monitored system is experiencing a drift. The first step is statistical data analysis and modelling at the instrument level, this gives instrumental field uncertainty assessment and compensation for secondary local effects. The second step is based on modelling the monitoring system as a whole. This gives a precise assessment of the correlations among different system areas and instruments. Moreover, this is the starting point for the third step, namely a model based hierarchical multivariate detection method, which is capable of signalling deviations from overall normality while controlling false positive rates.

This paper examines the roles of instrumentation in selected major construction projects in Singapore. In many projects, instruments had been planned properly and their interpretations enable engineers to identify problems before they occurred and to apply appropriate remedial measures. In a small number of projects, instruments had been misused and/or instrument data had been misinterpreted leading to incorrect judgments/decisions made. This paper aims to identify the causes of problems and the lessons learnt from these problematic cases.

Successful use of monitoring data to update performance predictions of supported excavations depends equally on reasonable numerical simulations of performance, the type of monitoring data used as observations, and the inverse analysis techniques used to minimize the difference between predictions and observed performance. This paper summarizes each of these factors and emphasizes their inter-dependence. Numerical considerations are described, including the selection of the type of finite element formulation, the initial stress conditions with emphasis on urban environments, the importance a reasonable representation of the construction process, and factors affecting the selection of the constitutive model. Monitoring data that can be used in conjunction with current numerical capabilities are discussed and a gradient-based inverse analyses technique that has been successfully used to update predictions of lateral ground movements measured close to support walls is summarized. Examples from application of these techniques from case studies are presented to illustrate the capabilities of this approach.

This paper provides an overview of the many potential benefits of an effective performance monitoring program for constructed facilities. It also outlines some specific methodologies to quantify these benefits in ways that non-specialists can understand and use. These include quantifying the benefits of monitoring and comparing them to the cost of monitoring. A case is described where the benefits of performance monitoring exceeded the cost by more than eight times. Another example shows that performance monitoring decreased the probability of failure by 40-fold. The goal of the paper is to provide others with the means to better define and quantify the benefits of proposed performance monitoring programs to other members of the Project Team so that effective monitoring can be performed throughout the project life.

The lateral behavior of bored piles in sand was examined by field tests at a site in Kuwait. The soil profile consists of medium dense silty sand underlain by dense to very dense sand with silt. Two single piles and two small groups each consisting of two piles were installed and load tested to failure. All piles were 0.3 m diameter and 5 m deep. One single pile was instrumented with electric resistance strain gages to measure the bending strains during the lateral load test. The pile groups were installed in two perpendicular directions and were load tested against each other to determine the influence of the loading direction on the lateral capacity. Test results indicate that the load deflection response is nonlinear. Both the ultimate lateral capacity and the deflection at working loads were examined. The response of the pile groups compared to the single piles was determined. Test results on the groups indicate that the direction of loading has a significant influence on the group behavior under lateral loading.

This paper presents a case study on the use of geophysical methods for determining the length of auger cast piles at St. Joseph Hospital, Savannah, GA. An expansion plan of the hospital involves adding one additional floor to the existing building. It is known the existing building is supported on auger cast piles, but no reliable information is available about the length and design capacity of the piles. Several geophysical methods were successfully utilized to determine the pile length and evaluate pile capacities. These methods included impact echo method, parallel seismic testing method and magnetometer method. Following a well planed testing program, all these testing were successfully conducted at the testing site. Results by these methods were found to give comparable results in estimating the length of these auger cast piles. This was then incorporated with information from site investigation to provide reasonable estimation on the bearing capacity of the existing foundation.

Dynamic pile installation monitoring is an alternate to expensive static compression load testing that when used in conjunction with the second can result in significant cost and time saving for a project while providing additional data across a site. The cost to perform one static load test can be compared to the cost of PDA testing and CAPWAP analyzing five piles. The cost-effectiveness of a load test program where a combination of dynamic and static load tests are performed, as well as the good correlation between static and dynamic capacity interpretations (using CAPWAP analysis) are demonstrated by a case study. The case study describes a load test program that was completed for the process area of the Sempra Cameron LNG project in Louisiana. Subsurface soils consist of Recent and Pleistocene Beaumont Clay soils, typically found in the Texas-Louisiana Gulf Coast area.

Micropiles, commonly employed for retrofit of existing foundations and new foundation construction in urban areas, present complex problems in analysis and performance prediction. This paper presents analyses of the three instrumented micropile load tests from two case histories. A total of 34 strain gauges were employed for the three load tests, consisting of spot-weldable gauges on the centralized reinforcing bars and embedment gauges within the neat cement grout surrounding the bars. Two of three test piles were tested to plunging failure and one to impending failure. The composite pile modulus was found to decrease with increasing strain levels within the pile, primarily due to the nonlinear behavior of the grout. The load distribution in the bond zone of the test piles was generally nonuniform, indicating that the mobilized unit bond stress is not constant. Significant pile tip resistance was generated as a function of total pile load and displacement for the two piles that plunged, even at loads less than those causing failure. Dissimilar strain levels measured by strain gauges within the grout and on the reinforcement indicate that perfect strain compatibility may not be present as is commonly assumed.

A bridge that is cast continuously with its abutments is known as an integral abutment bridge. A short stub-abutment supported on a pile-bent creates a flexible foundation that transfers the temperature and traffic-induced horizontal loading and eliminates the need for expansion bearings. Integral abutments are gaining wide acceptance by many states; however, a nationally accepted design methodology does not exist for their design and construction. Instead, each highway department depends on the experience of its engineers to develop adequate design criteria. By studying the response of such systems to horizontal loading, we may be able to extend the learned concepts to different structures and conditions. To study integral bridges, we instrumented a medium-length (300 ft) highway bridge in Trenton, New Jersey and have been observing the reaction of the bridge and its foundation to seasonal and daily thermal loadings. Design parameters of interest include the flexural behavior of the piles that support the abutment, the soil-pressure distribution behind the abutment, and the displacement and rotation of the superstructure during thermal loading. As such, we have gathered data every two hours for the past four years on displacement, rotation, strains, and pressures on the bridge and its foundation. In this paper, we will be sharing some of the data and will discuss relevant conclusions of our studies. In general, we have been witnessing an excellent correlation between temperature and displacement, expected behavior from the horizontally loaded piles, and a steady build-up of soil pressure behind the abutment. A short study of passive pressure build-up is also summarized.

This paper presents the results of vibration monitoring studies conducted during pile driving operations on Florida's Turnpike Enterprise (FTE) projects in central and south Florida. Seismographs were placed at various distances from the pile driving operations to measure the attenuation of peak particle velocity (PPV) with distance. The seismographs were synchronized in real-time with Pile Driving Analyzer (PDA) to develop correlations between actual driving energy generated by pile driving hammers and induced PPV, and between axial pile capacity and PPV. The study also examines the influence of predrilling on the vibration magnitude.

In Providence, Rhode Island, there have been several instances where construction activities such as pile driving or excavation have caused significant movements of adjacent ground and nearby structures founded on non-plastic silts. This paper presents a case study documenting substantial and unusual movements of a braced excavation that were observed during construction of a pile-supported sewer structure. Both inclinometer and piezometer data are presented. The piezometer data suggest that the unusual ground movements were likely attributed to excess pore pressures that were generated during driving of H-piles at the bottom of the excavation. The field instrumentation data will be particularly useful in future modeling efforts to better understand the performance of foundations and braced excavations in the Providence silts.

Washington Dulles International Airport (IAD), which serves the metropolitan area of the Nation's Capitol, is currently undergoing a massive construction program for handling increased passenger demand. Since inception, the airport has used mobile lounges to ferry passengers from the main terminal to the various mid-field terminals and gates. In the coming years, this will change as the first elements of the Automated People Mover (APM) system are placed in operation. The APM system will utilize electric-powered rail passenger cars running underground. The rail network will connect a series of passenger stations beneath the main terminal and each of the mid-field terminals. Safety considerations and possible adverse effects to adjacent structures, due to this construction, required an instrumentation program to provide timely and reliable information about the performance of both excavation retention systems and tunnel construction. Project plans and specifications outlined a series of instruments to include, among others, inclinometers and borehole extensometers to detect possible adverse movement. Due to a required need for frequent readings in high-volume traffic areas and the imposing conditions of placing an instrumentation system within active aircraft operations areas, an automated data acquisition program was proposed. This case study examines the design, implementation and management of data for an automated total station (AMTS), inplace inclinometers (IPIs), and wireless multiposition borehole extensometers (WMPBX) used in an active airport environment. Special consideration of electromagnetic interference (EMI), instrument design considerations for use in difficult access, high-volume traffic areas, and automated data management are provided.

A new 3.8 km long underground railway with three cut and cover stations is under construction beneath the historic inner city of Amsterdam, as part of the new Noord/Zuid Metrolijn. The sensitive conditions in Amsterdam place high demands on settlement control and monitoring of structures which are potentially affected by the works. 74 robotic total stations have been installed on key building facades along the route taking readings from over 7500 prisms on over 1200 buildings and bridges. These are in addition to over 2000 precise levelling surface settlement points and a significant number of remotely monitored sub-surface instruments. This paper describes some uses made of the data obtained during the base monitoring and early construction phases continuing from the paper presented at FMGM 2003 which covered specification, procurement and installation of monitoring instrumentation.

The increasing pressure on public transport has resulted in the development of several mega projects in and around the Rotterdam Central Station area. At the moment this area is being transformed to a modern public transport hub. One of the projects is the expansion and upgrading of the existing underground metro station. The building activities during the first phase of the project were executed very close, up to 1 m, from the existing metro station. The probability of causing deformations to the metro station was therefore very high. The contractor put a monitoring system in place consisting of a robotic tachymeter in combination with tilt meters. The monitoring system was working continuously, the monitoring results were presented on-line using an internet application also providing the on-line check on the hazard warning levels. The most prominent risk, interference of operation of the metro station, did not occur. Full accessibility of all services was maintained during all building activities. The monitoring system operated according to contract specifications. The on-line presentation and checking on hazard warning levels was very helpful in detecting the effect of building activities on the metro station. Monitoring has been used successful to control building risks. As a result of refraction problems, a system with more internal control was recommended for phase 2 of the project. The monitoring specifications for phase 2 were set up with two tachymeters in combination with crack meters placed over the station section joints.

The construction of three deep shafts forming part of the Influent Pumping Station (IPS) at Changi Water Reclamation Plant project required the installation of circular diaphragm (slurry) walls followed by the top-down casting of structural reinforced concrete lining walls. This paper describes the performance monitoring of the circular diaphragm walls utilizing a number of diaphragm wall panels of each shaft instrumented with inclinometers and vibrating wire (VW) strain gauges. The performance monitoring of the diaphragm walls allowed the construction of IPS shafts in 8 stages rather than originally planned 10 stages, reducing the critical construction time by approximately 2 months for each shaft. It also minimized a number of underpinning joints between successive stages of inner ring walls resulting in additional time and cost savings. The use of pro-active engineering during construction, together with comprehensive instrumentation ensured that all stakeholders were satisfied that changes to the construction sequence could be made safely and effectively, providing real benefits to the Project. The Pumping station facility was successfully commissioned during the last quarter of 2005, under budget and ahead of schedule.

Tunneling using earth pressure balance (EPB) tunneling methods has been active in Los Angeles over the last seven years. Three recent large-diameter EPB tunnel projects have been completed to create approximately 32km (20 miles) of precast concrete lined tunnel excavated through alluvial soils and soft, sedimentary rock. This paper addresses monitoring of ground surface subsidence using data collected from geotechnical instrumentation and TBM performance parameters. TBM operating data are used in conjunction with surface-installed instrumentation to predict surface subsidence. TBM operations may then be adjusted to reduce potential settlement-related damage to adjacent structures or utilities. Monitoring instruments using remote access is also addressed. The paper provides case histories of successful performance monitoring to support future urban tunneling projects.

Reconstruction of Pennsylvania Avenue in Washington DC provided a unique opportunity to instrument an historic house to determine its response to construction vibrations. To that end three cracks in the house, two on the interior and one on the exterior were instrumented with a micro-meter crack displacement sensor capable of measuring changes in crack width as small as 0.4 micro meters. This one sensor was employed to measure the micro-meter response of the crack to both dynamic (construction vibration) as well as the long term (weather) effects. As has been found with many other structures, the long term climatological effects produce greater crack response than do construction vibrations at levels that can be perceived and at times can be described as annoying.

This paper describes the use of settlement and piezometric data gathered in connection with the Boston Central Artery/Tunnel (CA/T) project to estimate the compressibility of a very dense, stiff glacial till. The data were gathered to measure the effects of excavations for the CA/T project on the adjacent One Financial Center (OFC) skyscraper. The CA/T excavations adjacent to OFC were approximately 34 m deep, approximately 21 m below the building foundation level, and supported by a 1 m thick slurry wall with closely spaced internal shoring elements. OFC is a 46-story steel tube frame tower and 5-story atrium, with a 2-story below grade basement. The tower is supported on a 2 m thick concrete raft and the atrium is supported on spread footings, both bearing on a dense glacial till. The OFC structure and the adjacent ground were heavily instrumented with interior and exterior settlement points, tilt meters, vibrating wire piezometers, vibrating wire strain gages on select OFC structural elements and inclinometers within the CA/T tunnel slurry wall. Measured excavation induced ground and building movements were very small because of the extremely rigid excavation support system. The building did experience some small settlements and rebound, of no structural consequence, due to temporary groundwater lowering associated with the CA/T construction. This paper will focus on the use of the building settlement and vibrating wire piezometer data to calculate the compressibility of the underlying glacial till. It describes the effects on the estimated compressibility of some of the necessary assumptions such as the distribution of capillary tensions. Few data are available on the compressibility of very stiff earth materials. The calculated stiffnesses reported in this paper will be useful in estimating the settlements of stiff earth materials due for example to piezometric changes or the application of large structural loads.

In this paper, the feasibility of using elevator motion as a statistically repeatable excitation for use in structural health monitoring (SHM) of tall buildings is investigated. Robust SHM benefits from a repeatable excitation source, but in buildings this is problematic for many technical and practical reasons. Ambient vibrations are therefore often used for repeated system identification of such civil structures. In tall buildings, the movement of elevators contributes to the mix of ambient vibrations. The 17-story Factor Building on the UCLA campus is heavily instrumented for earthquakes, and has high-resolution real-time continuous recording of vibration data. There are 72 accelerometers distributed throughout the building in addition to nearby ground motion and borehole reference accelerometers. Using Factor as a test bed, experimental studies of elevator-induced building vibrations were conducted. Building monitoring was augmented with additional elevator sensors and a small shaker. Initial results indicate that elevator-induced vibrations are statistically separable from other ambient vibration components in both the time and frequency domains. However, it may be necessary to measure elevator position and/or elevator counterweight vibrations. Work continues on the development of a methodology to use the elevators as a repeatable source for SHM of the Factor Building and other tall buildings.

This paper presents the data collection and analysis of deflection and earth pressure measurements made on a concrete shoring wall in Atlanta, Georgia. The shoring wall serves as the permanent basement wall for a ten-story parking garage. The wall is approximately 30 feet high and was constructed using steel soldier piles and cast-in-place concrete lagging. The lagging was placed in 4½ foot lifts from the top down and was cast directly against the soil being retained. This soil consists of a thin veneer of fill overlying moderate consistency soils of the Piedmont Physiographic Province. Temporary lateral support of the wall was provided using one to two rows of grouted, tendon-type tieback anchors. Long-term lateral support is provided by the structure which has been constructed against the shoring wall. After completion of the structure, the tiebacks were released. At two locations, inclinometer casing was attached to soldier piles to measure lateral deflections of the shoring wall. In addition, five vibrating wire earth pressure transducers were placed behind the concrete lagging at several heights and varying positions relative to the soldier piles and tiebacks. Both deflection and earth pressure measurements were made as the excavation progressed and before and after tiebacks were stressed. Also, measurements have been taken for approximately one year after completion of the excavation and pressure measurements will be continued indefinitely in the future. The results of the wall monitoring are analyzed and compared with the earth pressure assumptions used in design, as well as other methods used to estimate lateral earth pressures and deflections for anchored wall systems. The measurements made to date, as well as future measurements will also be used to evaluate any changes in earth pressures that may occur over time and assess long-term deflections that occur in these types of structures.

Earth pressure cells, tiltmeters, strain gages, inclinometers, and total station-measured survey reflectors were used to monitor a cantilever retaining wall for 12 months from the start of backfilling. The lateral earth pressure on the stem was observed to be active near the end of backfilling, with a corresponding wall displacement of about 0.1% of the backfill height. However, sensor readings during the backfilling process showed the earth pressure distribution on the wall to be quite complex. Evidence was found for residual lateral stresses from the compaction process. Translation of the wall overnight following the construction workday reduced both the compaction-induced lateral stresses and stem deflections. The response of the wall to loading beyond that from backfill was observed by means of a load test. Changes in earth pressure and wall deflection weeks after backfilling were attributed to changes in temperature and rainfall events.

This case study highlights how design, construction and field monitoring can be combined to satisfy low movement criteria in the presence of difficult site constraints. The R.C. Harris Filtration Plant is located in south-eastern Toronto, overlooking Lake Ontario, and provides forty-five per cent of Torontonians with potable water. The existing structures are designated as both historically and architecturally valuable under the Ontario Heritage Act. A proposed expansion to accommodate a residue management facility required that construction activities would not interfere with the plant's operations. In order to preserve the historical and architectural presence of the site, the new facility will be housed in two cut-and-cover stepped excavations, 12m and 10m deep, between two highly-valued and sensitive structures. Concerns regarding potential movements at an existing, critical expansion joint within the potable water tanks influenced the Owners' designers to limit the allowable lateral deflection of one excavation support wall to 4 mm. A comprehensive monitoring plan was implemented to include: inclinometers, electrolevels, extensometers, precision and pile target monitoring, load cells, SMART cables, and thermistors with baseline readings obtained over several weeks to determine if mandatory accuracy limits were attainable. The design build team awarded the contract, crafted an alternative design that resulted in substantial savings over the original concept. Extensive FLAC (Finite Layer Analysis of Consolidation) analyses were performed to predict movements at each stage of construction. Monitoring of the movements and comparison with the FLAC predictions allowed the team to assess the need for design or methodology modifications during construction. Based on the contractor's willingness to commit to an extensive monitoring program to justify the optimized design, the contractor was able to satisfy the owner's objectives with a cost effective solution. Extensometers, installed within the potable water tanks, were imperative tell-tales for joint movements at the critical junction between the Filter Building south face footing and the slab beyond. Over the subsequent 12 months, real-time monitoring of the extensometers showed negligible movements across the joint at the Filter Building's south face footing while the accompanying instrumentation proved total construction-related horizontal movements of 6 mm to 10 mm at the same location proving that the extensometers placed in the tank were able to provide the client with the necessary comfort to modify the allowable lateral deflection.

The axial and lateral behavior of soldier piles during jet grouting beneath a temporary excavation shoring wall has been evaluated from vibrating wire strain gage and inclinometer data obtained from several instrumented piles. Vibrating wire strain gages and inclinometer casings were installed in several soldier piles to measure wall performance as excavation and tensioning of ground anchors progressed during wall construction. Based on the analysis of system performance, it was determined that jet grouting would be employed after three lifts (approximately 4 to 4.3 meters) of excavation and wall construction due to a very soft/loose, saturated alluvial soil zone from 6.1 to 15.2 meters and for minimization of anticipated groundwater migration through the excavation face during subsequent excavation and wall construction. Strain and temperature measurements, as well as inclinometer profiles, were collected as jet grouting was performed near the instrumented piles. The data obtained were analyzed to evaluate the effects of jet grouting on axial load, bending moment, and soldier pile deflection.

In order to protect a high-voltage electrical ductbank during excavation for the replacement of a storm drain located 9.2 m to 10.7 m below the ground surface and as close as 4.1 m away, an anchored soldier pile wall shoring system was designed and installed with the goal of minimizing both lateral and vertical movements. Due to the critical nature of the project and the potential economic loss associated with disruption of power that might result from excessive displacement of the ductbank, an extensive instrumentation program was developed and implemented. In order to provide the best available prediction of anticipated displacements prior to excavation of successive lifts, back analyses were performed utilizing the data obtained during the most recent stage of excavation. Attempts were made to incorporate FLAC into UCODE, software developed as an optimization tool, however more success was obtained with the trial and error approach described. The goal was to provide the highest probability that target displacement restrictions would not be exceeded and to identify prior to excavation if remedial measures were needed.

This paper describes the monitoring of cut-slopes and the retaining wall that was adopted at CWRP site. During construction, thick deposits of soft marine clay, not discovered during previous site investigations, were encountered at the northern and eastern project boundaries. A high quality supplementary site investigation combined with the performance monitoring of slopes allowed the risk of instability in these areas to be effectively managed with the result that the use of relatively lower safety factors than traditionally adopted could be accepted. In addition, a detailed re-evaluation of the anticipated behavior of the CBP retaining wall combined with performance monitoring of the retaining wall and cut slopes allowed the originally planned jet grout ground improvement works at the location of EJC to be omitted. The use of pro-active construction management and resident engineering during construction, together with comprehensive instrumentation, robust data acquisition and continuous data review ensured that the risk of slope and retaining wall instability was well managed. This approach resulted in significant direct and indirect cost and time savings to the project and all project stakeholders were satisfied. The slopes and retaining wall at CWRP performed satisfactorily without failure and the excavation has since been backfilled.

This paper focuses on the instrumentation and performance of a tall MSE wall. Project requirements for the expansion of Seattle-Tacoma International Airport called for the construction of a third runway to the west of the two existing runways. A significant volume of compacted earth fill was required to raise the grade a maximum of about 50 meters to meet the level of the existing runways. Although embankment side slopes were allowed for much of the filling, adjacent creeks and tributary wetlands dictated the use of three tall MSE walls to limit the extent of embankment fill. The North Safety Area of the third runway required the construction of a 26 meter MSE wall. Performance monitoring included strain gage-instrumented reinforcement strips, inclinometer installations with sondex settlement rings, optical survey of wall facing for vertical and lateral movement, and piezometers. This paper briefly presents various wall design issues, concentrating on the aspects involved in the instrumentation of the wall and the subsequently observed performance during and after construction.

This paper presents a remedy case of a large-scaled trench collapse during the construction of a deep cylindrical diaphragm wall located in the south of Taiwan. Through a well-organized field monitoring system and suitable countermeasures, the potential disaster was mitigated in time. Thirty-two panels in total were designed to form the 70 m-diametered diaphragm with 1.2 m thickness and 90 m depth. During the trench excavation, a deep and large collapse of soils, approximately 110 m³, occurred at the depth of GL.-43 m to GL.-52 m in the trench. The overlapped reinforcing bars (rebar) of previously installed panels were serious deformed and impeded the coming rebar cage insertion. A series of monitoring activities including ultrasonic sounding and piezometer measurement was performed to figure out the causes and damaged situation. Relevant remedial measures as well as the monitoring data during the post-treatment are addressed. Three main concerns are concluded : (1) a well-organized field monitoring system during construction would be helpful for judgment in case any accident occurred, (2) an improper construction activity using percussion drill inside the coming-close cylindrical diaphragm wall built up the excess pore water pressure of the confined aquifer at the collapse depth and resulted in the serious collapse, and (3) the long stand-by duration of the excavated trench would increase the possibility of collapse.

The continuous monitoring of deep excavation pits in the framework of the observational method, in sense of an "interactive / iterative geotechnical design", has been established as an integral and indispensable part of the safety concept. The monitoring indeed conduces not only to the verification of the theoretical model but also to the supervision of the construction process with the aim of damage prevention. The concept of an interactive / iterative adaptation of the construction process as a reaction on the results, gained from the continuous monitoring with the aim of damage prevention, is discussed within this paper by means of an example of an excavation pit for a high-rise building project in Frankfurt am Main where heaves occurred on an adjacent building induced by anchoring works on the retaining structure.

The real time monitoring for the Olive 8 project in Seattle is described. This project involved construction of a 39 story structure with 5 levels of below grade parking. The 76 ft deep excavation next to an adjacent building required a hybrid support system consisting of large soldier piles with tightly spaced soil nails in the upper portion and steeply inclined tieback anchors in the lower portion. Because the City of Seattle limited lateral movements to 1 inch, engineers implemented a detailed monitoring system. Conventional inclinometers and optical survey points were supplemented by real time monitoring consisting of a web camera and an automated total station. This paper summarizes the philosophy behind the real-time instrumentation and shows how the total station data complemented the conventional inclinometer data. Data reduction techniques are described and performance data are presented. Finite element simulations of the excavation process showed the critical observation was the cantilever movements at the top of the support walls. Survey prisms were mounted at three such locations along the west wall to provide real time performance data. A project web site allowed all interested parties access to the data. The paper illustrates how real time monitoring and careful design can be used to great effect.

Different procedures for performing the standard penetration test (SPT) were employed during the site investigation at a fluvial sand site along the Ohio River. Comparison of the collected data shows that the SPT blow counts, i.e. N-values, were significantly affected by the test procedure used, due to the "flow-sand" phenomenon that occurred in the sandy soils below the groundwater table. The test procedure used can also have an effect on the laboratory test results obtained from the soil samples, such as grain size distribution. Based on experience at this site, reasonable SPT results can be achieved using either the mud rotary drilling method or the hollow stem auger method; however, if the hollow stem auger method is used, the insides of the augers need to be filled with bentonite mud during the test, and the mud should be added each time the augers are advanced.

In the process of replacing a corroding 2.4-meter diameter corrugated metal culvert, the utility contractor determined that the culvert paralleled a high voltage electrical ductbank for a distance of approximately 91.5 meters. The invert of the culvert was on the order of 9.2 to 10.7 meters below and as close as 4.1 meters away from the ductbank. The goal of the instrumentation program developed and described in this paper was to minimize the risks assumed by the owner, design engineer and contractor in pursuing this project by: 1) enabling all parties involved to know the actual movements along the ductbank as they occurred so that construction could be stopped if excessive displacements were observed, thus ensuring protection of the ductbank; and, 2) providing the design engineer with data that would enable back-analysis resulting in reasonable estimates of material properties that could be used for predicting the displacements that might be expected during the next and successive stages of construction. This process was developed with the intention that additional lateral support and soil improvement strategies would be decided upon during the excavation process.

A comprehensive field instrumentation, monitoring and assessment programme was implemented during the early part of 2004 to examine the pattern of loadings transmitted to high voltage overhead line support tower foundation systems following an imposed load event. The loads were applied by the controlled release of tensioned conductor bundles at each tower cross arm simulating a series of broken cable events. Each load event triggered a high frequency data acquisition system to record the magnitude and duration of loads within the tower support system together with the cross-arm displacements (derived from accelerometer readings). Load cells also measured the redistribution of loads within the remaining conductor sets following each broken cable event.

Within the framework of the feasibility study for a radioactive waste repository in a geological formation, the National Radioactive Waste Management Agency of France is constructing an underground research laboratory within the Callovo-Oxfordian argillite formation located in eastern France. During the sinking of the laboratory's access shaft and during excavation of the galleries, the mechanical and hydromechanical behavior of the argillite was monitored. A vertical mine-by test was carried out at depths between 460 m and 476 m in the main shaft. 12 boreholes were drilled downwards from a niche, where deformations and pore pressures were monitored. Another 11 boreholes were instrumented with mechanical and hydraulic sensors in the galleries. This paper is devoted to the instrumentation, the installation procedures and some first measurement results regarding the mechanical disturbance of the rock around the shaft.

This paper describes the various aspects upon which the Itaipu engineers based the design of a dedicated automatic data acquisition system (ADAS). It also discusses some of the technical problems that were encountered during the design and implementation and how these problems were resolved, the latter with the help of ISMES team. Mention is also given as to how the ADAS data management might be optimized in the future to become part of a dedicated system of optimization of the analysis of the auscultation (monitoring system) (SOAA) for (i) off-line production of periodic reports on the dam behavior, and (ii) to an on-line decision support system which continuously analyzes both manual and automated acquired data to provide an interpretation of the dam safety. Ways in which the ADAS could be integrated into a SOAA, along with data from other operating systems (such as the meteorological system and power plant production system) at the Itaipu facility, are also presented.

Drilled displacement piles (also known as augered cast-in-place displacement piles or augured, pressure-grouted displacement piles) are installed by the displacement of soil and subsequent placement of cement grout within the evacuated volume. Depending on the soil grain-size characteristics, soil behavior, in situ soil density, pile spacing, and pile diameter, the installation process can result in measurable densification and an increase in lateral stress. Cone penetration testing was performed at a beachfront site in Myrtle Beach, South Carolina. Baseline data were collected for the natural ground conditions and compared to data collected adjacent to a single drilled displacement pile and within groups of drilled displacement piles. The data, which are presented as a ratio of the post-installation measurements to the pre-installation measurements, support that the installation of drilled displacement piles in granular soil results in a substantial increase in tip resistance and sleeve friction as measured in the CPT. As may be expected, measurements near a single pile show that the measured post-installation tip resistance reduces as the distance from the pile increases. Within pile groups, the post-installation tip resistance in looser sands increases as the pile spacing decreases.

This paper describes a novel Electronic Nose (EN) technology integrated with an in situ vapor sampling tool known as the Membrane Interface Probe (MIP) for rapidly screening gasoline contaminated sites. The MIP is an in situ tool that samples vapor from the subsurface and transports it to detectors located on the ground surface. The electronic nose is an automated odor recognition device that detects and identifies chemical vapors based on the principles of mammalian olfaction. The technology at its current stage of development cannot determine the different compounds present in a complex mixture. However the integrated EN-MIP system was successful in detecting and estimating the concentration levels of gasoline contamination at various depths during in situ demonstration tests conducted in collaboration with the U.S. Environmental Protection Agency (EPA). Thus the EN-MIP system has the potential to be a reliable tool for rapid screening of gasoline contaminated sites.

A new water sensor using Brillouin Optical Time Domain Reflectometry (BOTDR) is presented in its early developmental stages. The sensor takes advantage of the growing fiber optic technology that particularly uses optical fibers as strain sensors on civil infrastructures. When these strain sensors are combined with polymers that react to target chemicals by swelling, the swelling forces transfer strain directly to the fiber for detection. By superimposing these two technologies, a sensor that is capable of detecting target chemicals continuously along a prescribed line from remote locations is possible. This paper is an overview on the theory of the BOTDR sensor technology along with results from a small-scale pilot test using a water sensitive polymer. The swelling potential of the polymer is proven to be strong enough to impose strains that are capable of being detected by optical equipment. Other properties of this hybrid sensor currently being investigated are selectivity, stability, rapid response, low detection limit, reversibility and longevity.

The evaluation, health monitoring and response prediction of soil and soil-structure systems during construction and due to extreme hazard conditions are on the verge of a significant paradigm shift. New and less expensive sensing technologies have enabled the development of innovative instrumentation and advanced interactive modeling tools. These tools, combined with recent advances in information technology including wireless sensor networking, data mining, visualization and system identification, promise significant improvements in real time monitoring during construction, sensor-assisted design and early warning of impending failure. This paper presents the newly developed Wireless Shape-Acceleration Array (WSAA) sensor that measures multi-dimensional acceleration and deformation profiles and constitutes a major step toward autonomous monitoring technology for soil and soil-structure systems. The WSAA sensor employs micromachined electromechanical sensors (MEMS), which have enabled gravity-based shape calculation along a sensorized substrate. WSAA uses MEMS accelerometers in a pre-calibrated, geometrically constrained array to provide long-term stability. This sensor array is capable of measuring 2D soil acceleration and 3D permanent ground deformations to a depth of one hundred meters. Each sensor array is connected to a wireless earth station to enable real time monitoring of a wide range of soil and soil-structure systems as well as remote sensor configuration. This paper presents the evolving design of this new sensor array as well a description of and preliminary data from an instrumented unstable slope in California.

This paper presents a case history of a recently completed portion of an ongoing ground improvement project in Northern New Jersey. The site is a former landfill underlain by soft, weak and compressible natural sediments. The project involved the design and implementation of a ground improvement program (GIP) consisting of dynamic compaction (DC) of the municipal solid waste (MSW) followed by implementation of a surcharge program to overconsolidate the MSW and the organic soils and to pre-consolidate the underlying soft varved clay soils. The heterogeneity of the MSW and the soft nature of the various natural strata made the conventional deterministic methods problematic and somewhat unreliable. Due to large variations in the published shear strength properties of the MSW and the inability to predict the strain compatibility between the compacted waste and the natural soil deposits, an observational method was implemented. As a result of constant field observations and measurements, large shear deformations were identified in a localized portion of the site that were subsequently mitigated. Removal of the surcharge fill, combined with installation of wick drains to accelerate the consolidation of the soils and improve their shear strength, enabled filling to continue safely.

Landfill operators depend on the available volume for waste placement, airspace, as their primary source of revenue. The ability to measure waste settlement and the corresponding increase in airspace is key to maximizing revenue and projecting cash flow. Waste settlement predictions in landfills are uncertain due to the inherent complexity of these systems and the relative scarcity of data. Bioreactor landfills, where moisture, nutrients, and temperature are optimized to accelerate waste degradation, are even less understood. In this paper, two experimental bioreactor landfills are considered: a filled 0.4-hectare cell in Harrison, Michigan, and a new 3-hectare cell in Smiths Creek, Michigan. Several pipes were installed and settlement profilers were used to measure the settlement within several discrete lifts. This data is valuable to understanding waste degradation and settlement as well as providing a valuable management tool to optimize bioreactor landfill operation and airspace utilization. This paper examines this application of settlement profilers and its value to bioreactor landfill engineers and owners. Preliminary results show promise for calibrating settlement estimates using these measurements.

As a part of a new Liquefied Natural Gas (LNG) import terminal located at coastal Louisiana, about 12,500 linear ft of retention dikes are being constructed around multiple LNG tanks. The 18 to 23 ft high dikes are constructed over 80 ft deep soft clay overlying a dense sand layer. The upper few feet of soft clays were stabilized in-place. The dikes are instrumented with settlement plates, inclinometers and piezometers, and monitored from the start of fill placement. To expedite consolidation of soft clays, prefabricated vertical drains (PVDs) were installed into the deep sand layer beneath the dikes extending laterally 50 ft from the dike toes. To optimize the PVD spacing, slope design and rate of fill placement, a test dike section was constructed with PVDs spaced at 2 ft and 4 ft centers. The selected settlement plates, inclinometers and piezometers data from the start of dike construction in May 2005 to February 2007 are presented. The data analyses and results of the dike performance and design optimization studies are also presented. It appears that rate of consolidation is similar for PVDs at 2 ft and 4 ft spacing as a result of significant soil disturbance effect at closer spacing causing reduced permeability in the smeared zone. Observations made at settlement plates and inclinometers were useful in evaluating in-situ C_h and stability during construction.

Slope indicators are commonly used in the evaluation and assessment of ground conditions affecting the highway infrastructure of roads and bridges when historic evidence, airphoto interpretation or judgment suggest that the natural or existing ground might develop instability problems through new construction or natural processes. During the planning and design stages of the re-alignment of two major Primary Highway routes in the Southern Region of Alberta, office studies and site reconnaissance indicated the possibility of slope instability concerns. These concerns warranted the installation of slope indicators to determine their validity and measures, if any, to ensure the suitability of the proposed routes. The slope indicator monitoring concurred with the projections of the site and office reviews allowing decisions to be made to ensure construction of the bridges and highways in stable terrain. These two case studies demonstrate the importance of using instrumentation to validate site observations and opinions, and to allow for sound decision-making.

The Piedmont Triad International Airport (PTIA) is undergoing an expansion including a new runway (Runway 5L-23R) and taxiway (Taxiway E) as a result of the construction of a regional hub for Federal Express. Part of the construction of the associated Taxiway E includes the construction of the embankment over a wetlands area in an alluvial floodplain. The presence of soft ground in the wetlands area required careful consideration of the effects of construction, due to permitting requirements. An instrumentation program was implemented to determine the fill placement rates or appropriate waiting periods during fill placement, and to prevent slope failures from occurring. This paper highlights key features of the instrumentation system. It describes the instrumentation system that was installed, the results obtained to date, and practical issues that were addressed during construction. The grading plans for the project indicate the construction of an 18 meters (60-feet) high earth embankment over the existing soft ground. The subsurface exploration indicated the soft ground profile to consist of an upper zone of alluvial soil underlain by a residual soil profile. A hybrid ground modification technique was used to stabilize the soft ground, allowing construction of the Taxiway E embankment without more intensive efforts. The use of ground stabilization to provide a working platform in conjunction with toe berms to maintain slope stability and wick drains to accelerate drainage, strength gain, and settlement offered benefits to all members of the project team. The instrumentation program resulted in both material and time savings, by allowing for the modification of the design based on field conditions, and reducing or eliminating the waiting periods between fill placement phases.

Instruments installed to demonstrate stability of embankments constructed in stages on soft glacial clay are suggesting strength gain due to drained shear stresses during consolidation periods. Undrained strength gains in the range of 20% to 25% have been measured in specially run DSS tests. Drained shear strain results in consolidation and consolidation causes strength gain. Although without an increase in vertical stress, the soil appears to have been mechanically overconsolidated. Minor clay structure changes also appear to contribute to the strength gain. The clays demonstrate increased brittleness and reduced pore pressure response after drained strain. This requires reconsideration of criteria used with stability monitoring instruments.

The Yellow river of China is known for having a river bed that is higher than its neighboring land. For centuries, the river dikes have been an imperative part of the protection for those who live along the river. Manual inspection from the shoreline has been the normal procedure to monitor the integrity of the river dike below water surface. This procedure is time consuming and dangerous, thus making an automated system highly desirable. Several schemes were evaluated in order to investigate the possibility of a practical and automated method to safeguard the river dikes. Systems tested included strain gauged steel angle, vibrating wire extensometer, and optic fiber Bragg grating based ground displacement monitoring devices. A test site was set up at a dike in Wu-Tze County, Henan Province. Inclined boreholes were drilled and the test instruments installed from the inside of the river dike. In order to validate the effectiveness of the design concept and sensitivity of the sensor systems, a rock pile was formed along the face of the dike first and then removed. The unloading simulated the effects of a dike scouring. The sensor readings were taken as the rock pile was removed. This paper describes the principles of the various monitoring schemes, presents results of the field experiment and discusses the implications in the safety monitoring of Yellow River dikes.

Slope stability of embankments in highly weathered shale encountered at shallow depths is a major concern in roadway design. This condition was encountered at a bridge location in southeastern Iowa, where dual bridges are part of a 4-lane state highway. The maximum embankment height is 12 meters at the north abutment and 8 meters at the south, with 3H:1V slopes in the longitudinal and transverse directions. Conventional soil borings with Standard Penetration Testing indicated the presence of highly weathered shale at shallow depths. The subsurface conditions indicated the presence of sloping highly weathered shale at both the north and south abutments. A 0.3-meter-thick layer of highly weathered shale was assumed at the clay/weathered shale interface and assigned undrained shear strength of 10kPa per Iowa Department of Transportation guidelines. Slope stability analyses indicated global slope instability, with failure surfaces propagating through the sloping and highly weathered shale layer. Various alternatives were evaluated at costs ranging from $3,000,000 to $5,000,000. In view of the high cost, a comprehensive subsurface exploration, laboratory testing, and monitoring program was implemented to evaluate strength and monitor slope performance. In-situ testing consisted of Iowa borehole shear tests in the highly weathered shale. Slope stability analyses indicated the slopes to be stable under both short-term (end of construction) and long-term (drained) conditions. Inclinometers and settlement plates were installed during construction to record slope movements. Monitoring data available thus far indicate insignificant movement. The judicious use of in-situ testing and an instrumentation program resulted in significant reduction in construction cost and kept the project within budget limits.

A detailed study has been performed of the settlements which occurred in the subsoils beneath two selected high embankments (the Pesnica connection embankment, and the Srmin high embankment), which were built as part of Slovenia's National Motorway Construction Programme. These embankments had to be built on very compressible subsoils of low bearing capacity and low permeability. Two measurement methods, using conventional settlement plates and a hydrostatic profile gauge which could be placed in specially installed measuring tubes, were used to obtain settlement profiles at several locations along the embankments. The results showed that the development of subsoil settlements at two selected locations of the Srmin embankment was very different, due to the heterogeneity and varying compressibility of the subsoil. The settlements of both embankments obtained by measurements using the hydrostatic profile gauge were very similar to those obtained using settlement plates, which were located close to the measuring tubes.

A power company is constructing air quality control (AQC) additions at a power plant site in Alabama, USA. The selected location for the AQC additions is near an area that has experienced periodic but regular lateral ground movements. An extensive study was carried out to investigate the magnitude and rate of movements and the factors controlling these movements. A slope stabilization scheme involving construction of one hundred 1.37 meter (m) (54 inch [in.]) diameter drilled shafts adjacent to the AQC additions was implemented to arrest lateral movements. A program of field instrumentation and monitoring was implemented to verify key assumptions during construction, evaluate the effectiveness of the stabilization scheme, and provide information that could be used to modify the stabilization scheme if field observations identified this necessity. Instrumentation included inclinometer casings within selected drilled shafts, inclinometer casings in soil between the shafts and landward of the stabilized area, fiber optic strain gages on shaft reinforcement, standpipe piezometers, and clusters of fiber optic pressure transducers. Data from the instrumentation was collected throughout construction and has proven to be instrumental in evaluating the performance of the stabilization scheme.

The results obtained from a marine sedimentary soil site, which was improved by Sand Compaction Pile (SCP) method with a high replacement area ratio at a quay-wall caisson foundation are analyzed. This soft marine sediment site originally had a thickness in the range of about 40 m. To install a caisson in the soft marine sediment, the top part of that layer was dredged to a level about 20 m, and then the remaining soil layer was improved by SCPs. The consolidation settlements were measured and compared with the values predicted by consolidation theory. The measured settlement was smaller than the predicted settlement. It is related to the fact that the prediction of the settlement in the SCP improved ground is only a function of the replacement area ratio, which is related to the area of SCP assumed to be a circle theoretically. However, the measured shape of SCP by boring tests was not circle type but an ellipsis type in site, because the sands were smeared into a weak clay layer and distributed in an ellipsis type of sand pile rather than circle due to the technique of SCP installation. The actual replacement area ratio was increased more than the value assumed in design stage. Thus, to estimate accurately the consolidation settlement another factor such as the amount of sand used for replacement should be incorporated.

This paper provides a case study where field instrumentation was used to assess the compressibility of Solvay waste (waste) and to independently confirm results from a laboratory testing program. A pilot study was performed that included laboratory testing, placement of 3 meters (m) of soil fill over a 4,100-square meter (m²) area of the waste, and installation and monitoring of field instrumentation to measure settlement and pore water pressure changes before, during, and following fill placement. The pilot study focused on evaluating the compression and time rate of compression behavior of the waste when subjected to vertical loading. The piezometer and settlement plate results were consistent and comparable with the laboratory data in terms of both the magnitude and time rate of settlement. Using field instrumentation data collected during the pilot study, a site-specific geotechnical model was developed to estimate the total and differential waste settlement under a vertical loading associated with a potential site reuse option.

Site characterization for a new 8.7 km (5.4 mile) railroad alignment traversing mountainous terrain suggested the presence of ancient landslides that presumably occurred during Pleistocene time. Excavation of the proposed alignment would extend to depths up to 46 m (150 ft) with the potential for either reactivating ancient landslides or triggering new ones. Excavation would expose sedimentary rock strata that exhibit considerable horizontal and vertical variation in strength and deformability but with a general tendency for vertical repetition of behavioral characteristics. Right-of-way restrictions limited rock cut slope angles to those steeper than traditionally used for these slide prone and highly erodible geologic strata. Cut slopes were designed to fit within the proposed right-of-way by developing countermeasures to minimize weak rock degradation, installing sub-horizontal drains to lower groundwater levels and developing an instrumentation program consisting of inclinometers and piezometers to monitor slope movement and water levels. Contingency plans to arrest global movement were to be employed if slope movements occurred beyond tolerable values. Instrumentation was monitored during and post construction. The inclinometer data indicated movement along distinct shear planes. However, slope movement generally ceased upon completion of blasting and excavation operations, although some inclinometers have shown several cycles of minor movement and subsequent stabilization attributed to perched water. Countermeasures to arrest slope movement were never employed. The use of an instrumentation program for this project allowed the owner to construct a safe and cost effective new rail line.

Eurocode EC 7 "Geotechnical Design", being the fundamental geotechnical code in Europe and, since 2004, mandatory in all countries of the European Union and EFTA, states that "when prediction of geotechnical behaviour is difficult, it can be appropriate to apply ...the observational method, in which the design is reviewed during construction". EC 7 is issued in two parts: Part 1 (EN 1997-1) "General rules", and Part 2 (EN 1997-2) "Ground investigation and testing". Whilst Part 2 provides guidance for the planning and interpretation of a wide range of geotechnical laboratory and field tests for parameter input into Part 1, it does not yet contain specific guidance for the performance monitoring of geotechnical structures typically carried out within the framework of the "Observational Method". In identifying this deficiency, the German FMGM Group has embarked on a standardisation project by means of the national DIN 4107 "Geotechnical Monitoring". Once DIN 4107 is finalised, it will be suggested for the introduction into the European standardisation procedure with a view to widening the scope of EN 1997-2. As currently drafted, DIN 4107 comprises the following four parts: Part 1: General rules; Part 2: Extensometer and convergence tape measurements; Part 3: Inclinometer and deflectometer measurements and Part 4: TPC (Total Pressure Cell) measurements. The principal outline and content of the current draft versions are presented in some detail, with particular reference to Part 1. The observations are made against the background of the US debate on geotechnical and geo-instrumentation standards of the years 1997–98.

Earth pressures exerted on tall, rigid retaining walls by confined backfill zones are not well understood. Many factors such as: complex soil-structure interaction, soil arching within the backfill, vertical shear transfer, seasonal temperature effects, and variable methods of construction affect the earth pressures. A new monolithic wall for the McAlpine Lock Replacement project of the U.S. Army Corps of Engineers, in Louisville, Kentucky, was instrumented to measure earth pressures and temperatures. Data were collected for two years and continues. Pressures and temperatures were measured for monolith L-11. Construction procedures greatly affected retrieved data. Earth pressure readings were affected by changes in backfill temperature because of thermal expansion∖contraction in the pressure cell oil chamber. A data filtering procedure was developed and subsequently verified through laboratory testing. Data adjusted with this filtering method agreed reasonably well with earth pressures estimated from theory.

This article describes the design and installation of an innovative plumb line system installed on the face of a double-curvature concrete arch dam. The system measures horizontal movements of the dam body with an accuracy of ±0.1 mm. The plumb lines have been in service for more than three years and demonstrate the continued integrity and safety of the dam.

The Lauenburg Lock is located next to a highway and a 40 m high slope with homes on top. Prior to the construction of a replacement lock, a monitoring system including 4 inclinometers, 8 extensometers and 11 groundwater monitoring points was installed. All data are processed and real time available in an online monitoring system. It was observed that there are natural deformations in the slope and changes in the groundwater head before the construction started. Both are dependent on meteorological conditions. During groundworks unexpected peaks in the groundwater monitoring points were observed. At the same time, the slope deformation did not produce any exceptional readings. An elevation of the groundwaterhead of up to 2 m was observed during trenching of the slurry wall. Over night it decreased to normal level and was found to be uncritical. Later one trench collapsed. Additional temporary groundwater monitoring points were installed close to the slurry wall. The readings showed peaks in the water head of up to 4.5 m, which were an explanation for the collapse. To enable further works to be carried out, vacuum drains were installed to temporarily lower the water head close to the actual works. The water pressure was effectively reduced and trenching could be carried out without any further problems.

The L-L Tailings Dam is a cycloned sandfill dam of 169 m ultimate height constructed by hydraulic method across a glaciated valley. The dam is founded on soft swamp and lacustrine deposits overlying competent glacial till in the valley, and a complex volcanic-sedimentary bedrock sequence overlying granodiorite basement along the north valley slope. This paper highlights the central theme of applying the Observational Approach to maintain the stability of the L-L Dam under difficult foundation conditions. The three-decade long construction period offers an opportunity for the owner to take advantage of this approach. The dam design has evolved based on the observed foundation behaviour to achieve a safe yet economic design. Experiences, gained through monitoring of instrumentation including inclinometers, piezometers, settlement gauges and seepage weirs in an ongoing construction environment, are also discussed.

Dams are important engineering structures constructed to control, supply, or divert water. Seepage and high pore pressures are the most important phenomena that endanger the safety and stability of a dam. Because of the importance of primary control and evaluation of hydraulic performance of foundation ground and grout curtain of embankment dams at the beginning of operation, Alavian dam, located in the north-west of Iran, was selected as a case study and its performance was evaluated using records of pore water flux and pressures during first filling. It was found that the seepage through the foundation joints was affected by the changes of the reservoir water level although the joints were sealed by grouting. This indicates that there is an optimum length for the gallery block which minimizes the number of associated joints and the structure of the gallery doesn't tolerate critical deformations. This length depends on the engineering characteristics of the foundation ground.

The Pichi Picún Leufú Hydroelectric Project (PPL) includes a 54-m high compacted gravel embankment, concrete spillway and powerhouse on the 1000-km long Limay River that flows from the Andes Mountains to Atlantic Ocean in the Patagonian section of Argentina. With no impervious core, due to lack of suitable soil, the embankment cuts off flow with an upstream concrete slab keyed to a plinth and vertical cutoff wall. PPL has a 1045-m long crest, and a spillway capacity of 10,000 m³/s. Built in 1993–1999, Petrobras Energy S.A. operates PPL for the Argentine government. The principal parameters of concern for the embankment dam performance include settlement, displacements between the upstream concrete slabs and plinth, structural strain in the concrete slabs, and seepage. The instruments to obtain these measurements included settlement cells, vibrating wire extensometers, strain gauges, resistance temperature devices, precision surveying and a downstream stream gauging station. For the concrete structures on the right side of the dam, the principal parameters evaluated are the behavior of the grout curtain, seepage, deformations, inclination and piezometric head acting on the base of the concrete structures. Instruments include vibrating wire and hydraulic (standpipe) piezometers, borehole extensometers, an inverted pendulum, triaxial joint displacement gauges and vibrating wire weir level sensors. This paper presents performance of the geotechnical and structural instrumentation up to the current time with accent on the structural performance since reservoir filling. Instrumentation data obtained with both automatic and manual data acquisition has been successful to date. The behavior of the dam and structures have been as anticipated in the design.

A monitoring system based on temperature readings using fiber optic cables was designed for leakage detection through possible defects in the cutoff wall of the Peribonka main dam. The system is based on the heat pulse method to measure the apparent soil thermal resistivity. By combining a line heat source with a fiber optic distributed temperature measurement, local analysis of heat transfer can be performed to detect, locate and estimate the leak percolating velocity. Laboratory tests were carried out in clean granular sand having a hydraulic conductivity (k_Sat) of 10^–3 m/s. The apparent thermal resistivity measured with the system decreased from 0.6 m-K/W to negligible values when the Darcy velocity of the percolating fluid was increased from 10^–6 to 10^–4 m/s. This shows the capacity of the proposed system for detecting leakage in these kinds of soils. Finite element modeling of the experiments shows the same trend. Three hybrid cables were installed in boreholes through the alluvial foundation of the Peribonka main dam by way of boreholes. The cutoff wall is now completed and preliminary measurements indicate no significant seepage.

This paper provides an overview of the Penn West CO2-EOR Pilot Monitoring Project initiated in Western Canada in early March, 2005. Monitoring the Penn West CO2-EOR Pilot Project presents an opportunity to apply, develop, and enhance our knowledge of the CO2-EOR storage processes and especially to develop monitoring technologies that will make this technology to mitigating greenhouse effects predictable, environmentally friendly, sound and robust. In particular the paper will focus on the completion of a dedicated observation well within the pilot area containing a geophone string, multiple pressure and temperature sensors and two downhole fluid recovery systems (FRS) — all cemented in place at 1600 m depth. These tools represent an opportunity for both short- and long-term monitoring by vertical seismic profiling (VSP), passive seismic, pressure, temperature, and geochemical monitoring. Synthesis of this information will provide the basis for recommendations regarding the deployment of downhole technology in observation wells used for the monitoring and verification of CO₂ movement. This paper concludes with a discussion of these aspects of the project and will provide valuable insight for the many current projects and the professional community considering the deployment of sophisticated multi-instrument strings in field demonstration projects of CO₂ storage.

The Electric Boat facility in Groton, Connecticut consists of three Graving Docks, each supported by interlocking circular and diaphragm cofferdam structures. Owned and operated by the General Dynamic's subsidiary Electric Boat Corporation, these graving docks are used for the construction and maintenance of the United States Navy's submarine fleet. Graving Docks 1 and 2 were constructed between 1961 and 1968, followed by Graving Dock 3, known as the Land Level Construction Facility, which was constructed from 1975 to 1977. In May 2004, sheetpile cofferdam cell S-2 at Graving Dock 3 experienced an interlock failure during a routine dewatering evolution performed to drydock the USS Jimmy Carter. This event rendered Dock 3 unavailable for submarine construction and launched a series of initiatives at the facility to investigate the cofferdam failure, stabilize and repair cell S-2, and monitor and evaluate the condition of all three Graving Docks. As routine submarine maintenance continued at Graving Docks 1 & 2, geotechnical instrumentation played a pivotal role in restoring confidence in the ability of the aging cofferdam structures to support the construction and maintenance of nuclear powered submarines. A total of ninety-four (94) vibrating wire piezometers were installed near the base of each cofferdam cell to monitor hydrostatic levels. These instruments were automated using a customized data acquisition system (ADAS) to provide real-time changes of in-situ pore pressures. This data is used during routine but critical dewatering activities to monitor hoop stress conditions in each cofferdam cell and provide the basis for controlling the rate of flooding and dewatering at the Facility. This automated system has demonstrated that pore pressures can be controlled within individual cells to remain within operating range and therefore restore confidence in the Facility so that time sensitive construction and maintenance activities can continue.

The Vibro stone column treatment method is widely used for site liquefaction mitigation. Today, the quality control of stone column installation includes the monitoring, recording, and displaying of vibrator penetration depth, energy consumption, gravel consumption, and air pressure to continuously aid the operator and the inspector. In the past 15 years, with the advance of electronic and computer technology, the data acquisition and data recording system for the vibro stone column construction has been developed and widely used in many projects involving the authors. The need for improving the quality of construction led the development of the i-Vibro system, an integrated instrumentation system using TCP/IP based data acquisition technology, wireless communication, graphical user interface, and GPS satellite navigation and gyro technologies for accurate underwater construction. Given the real-time display and comprehensive data, the design geotechnical engineer can better analyze the site response and evaluate the effectiveness of vibro stone column treatment. This paper covers the vibro stone column instrumentation for several projects, including the Mount Hermon and BART (Bay Area Rapid Transit) marine test section projects. The marine project involved the installation of stone columns in over 90 feet of water and only 1.52 meters (5 feet) away from the San Francisco - Oakland trans bay subway tunnel.

The East Side Combined Sewer Overflow (CSO) Tunnel in Portland, Oregon will pass through a major elevated freeway interchange where it will negotiate a series of steel H-pile deep foundations. Given the high risk of encountering an obstruction during tunnel excavation, geophysical techniques were used to assess the risk of encountering H-pile foundations. Borehole ground penetrating radar and magnetometer surveys were performed along the proposed tunnel alignment to detect potential deviant H-piles. Results of the survey indicated a deviant pile that potentially conflicted with the proposed tunnel alignment and the alignment was subsequently relocated to avoid the potential obstruction.

A local identification technique is developed to analyze the response of soil and soil-structure systems utilizing measurements from a newly developed Wireless Shape-Acceleration Array (WSAA). Local analyses of the constitutive behavior of these systems are performed using acceleration records provided by a cluster of closely spaced sensors. The developed new technique does not require the availability of boundary condition measurements, or solution of an associated boundary value problem. The constitutive behavior at a specific location is analyzed independently of adjacent response mechanisms or material properties. Numerical simulations of a soil-retaining wall system were used to demonstrate the capabilities of this local system identification technique. The combination of the developed Wireless Shape-Acceleration Array (WSAA) and local identification technique constitute a step toward autonomous monitoring technology and analysis tools capable of providing a realistic picture of acceleration, large deformation and failure of soil and soil-structure systems.

Generally visual examination of drilled shafts constructed under dry conditions provided the only reliable way to determine their shape. The shape of a drilled shaft becomes highly uncertain, however, when constructed under slurry-supported conditions. A mechanical caliper can provide limited information about shape under slurry conditions. Callipering such shafts using advanced sonar techniques now can provide much more information about shaft shape, volume and vertically. In addition Engineers now have more reliable way to assess strain gage data commonly used to determine the distribution of shear resistance at specific elevations along a shaft subjected to axial loads. The main value of sonar caliper technology to the geotechnical and foundation industry at large resides in its ability to improve quality assurance for clients/owners and quality control for drilled shaft contractors.

Based on a variety of case histories of site investigations, including extensive bore hole data, laboratory testing and geophysical prospecting, an empirical formulation is proposed for the rapid determination of allowable bearing capacity of shallow foundations. The proposed expression corroborates consistently with the results of the classical theory and is proven to be rapid, reliable and safe. It consists of only two soil parameters, namely, the insitu measured shear wave velocity, and the unit weight. The unit weight may be also determined with sufficient accuracy, by means of another empirical expression, using the P-wave velocity. It is indicated that once the shear and P-wave velocities are measured insitu by an appropriate geophysical survey, the allowable bearing capacity may be determined rapidly and reliably through a single step operation. Such an innovative approach, using the seismic wave velocities only, is considerably cost and time-saving, in practice.

The paper presents a detailed discussion of the fully-grouted method, installation procedure, theoretical background, laboratory test results of several cement-bentonite grout mixes, field examples of the application, and a seepage model that evaluates the impact of the difference in permeabilities between cement-bentonite grout and surrounding ground in the measured pore-water pressure. The discussion of the procedure includes a detailed description of the piezometer installation, materials, mixing, and construction tips associated with the fully-grouted method. The theoretical background that supports the use and application of the fully-grouted method is presented and discussed. The paper shows the laboratory test results of six cement-bentonite grout mixes in terms of permeability and unconfined compression strength. The measured permeabilities and unconfined compression strengths are in the range of 1.0 x 10^–5 to 1.0 x 10^–7 cm/s and 91 to 1790 kPa, respectively. The results of the seepage model show that the permeability of the cement-bentonite grout can be up to three orders of magnitude greater than the surrounding ground without significant error in the measured pore-water pressure. Finally, three field examples in which the fully-grouted method was applied successfully are presented and discussed.

nees@UCLA is one of fifteen laboratories that make up National Science Foundation's George E. Brown Jr. Network for Earthquake Engineering Simulation, known as NEES. nees@UCLA is a mobile dynamic structural testing laboratory. It's equipment portfolio includes large shakers for exciting structural systems, numerous sensors for monitoring response within the excited structure and within the surrounding soil, and real-time high-resolution digital data acquisition and dissemination capabilities. Dynamic forces up to 200,000 lbs can be generated, and acceleration responses from micro-g up to 2g can be monitored. This paper provides an overview of the nees@UCLA mobile field laboratory and the details of representative projects.

Due to very poor upper soil conditions, it was elected to support the process plant facilities for a Liquefied Natural Gas Plant owned by Atlantic LNG in Trinidad on a grid of Deep Soil Mixing (DSM) columns. The DSM columns, which were generally constructed in a grid pattern under all foundations, were installed from the ground surface down to the underlying hard, clayey soils, generally referred to as the Old Marine Sediments (OMS). The depth to the OMS was typically 10 to 12 meters. The DSM columns were installed using instrumented triple-shaft drilling equipment. During the entire installation process real-time measurements were taken and recorded regarding depth of penetration, penetration and withdrawal speed, shaft rotation speed, and slurry injection rates. Also recorded during installation was the energy measurement and what was referred to as the tool-bar loading. The energy measurement in combination with the tool-bar loading was used to verify that the DSM had penetrated into the underlying OMS as required by design. The load testing of the DSM columns was performed to both verify the quality of the installation procedure and to confirm the actual settlements of the mat foundations constructed on the DSM columns would be within predicted levels. It was also elected to perform an instrumented load test of the DSM column in an effort to determine both the vertical and horizontal stress distribution through the column.

A new hydraulic conductivity test method was developed and applied for the clay liners in the solid waste landfill site, and has attained high accuracy and productivity. Innovation exists in the single-unit apparatus of united sampler and specimen mould. Sampling can be easily conducted on the level surface as well as on the slope by driving the sampler into the ground with a hammer. The test also can be done easily in the simplified manner in the field laboratory with a high constant water-head in a short time without transporting samples into the precision machine laboratory. This single-unit apparatus is used for permeability test in the field laboratory as well as for sampling in-situ. Hence authors named this system as a handy permeability test with a single-unit apparatus. High accuracy was obtained by water sealing mechanism in the single-unit apparatus. High productivity had been attained as that the hydraulic conductivity of 109 samples were evaluated in half a year and be conducted in every 270 m² in the MSW landfill site.

In order to characterize the ground vibration attenuation with distance in Southern Taiwan Science Park (STSP), a series of small-scaled in-situ vibration tests, including falling weight tests and shaking tests, were conducted by National Center for Research on Earthquake Engineering (NCREE) at sites in STSP where Taiwan High Speed Rail (THSR) passes through. Those tests were performed on the ground surface, on shallow foundation, and on proto-type pile foundation. For falling weight tests, hammer weights of 8, 12, 22, 26, 43 metric tons and drop heights of 0.5m∼3.5m were adopted to generate different levels of ground vibration. The decay of ground vibrations with respect to distance was monitored to deduce attenuation coefficient. In this paper, results of all the falling weight tests are summarized and compared with those of in-situ measurements of ground vibrations excited by test runs of THSR trains. Conclusions show that the attenuation coefficients of ground vibration deduced from the falling weight tests present a similar trend to, but with larger values than, those deduced from measurements of test runs of THSR, and therefore can be used to predict the decay of ground vibrations induced by the operation of high-speed trains.

A key issue in the field of underground waste storage is the investigation of the barrier function of the host rock and the sealing of the disposal tunnel. For the demonstration of gas escape, a large scale "gas path through host rock and along sealing experiment" is currently being conducted at the Mont Terri Rock Laboratory in Switzerland. The experiment is focused on the gas paths along an excavation damaged zone (EDZ) developed around a sealed microtunnel section and the gas paths through the excavation undisturbed host rock. The instrumentation of the test site comprises suitable sensors to assess the hydraulic and geo-mechanic characteristics and the coupled hydromechanical processes around the tunnel. The first test data show a good response of the sensors to the induced pressures and stresses.

The RH-Extensometer (Reverse Head Extensometer) was developed to carry out continuous displacement measurements ahead of the tunnel face. Readings are made despite successively removing parts of the measuring rods in the course of the excavation procedure. This is possible because the head of the extensometer, containing the sensors and a data logger, is placed at the base of the borehole (i.e. it is the furthest away from the tunnel face and the last element to be reached). The recorded measurement data are transferred to the operator at the face of the tunnel by radio transmission. RH-Extensometer monitoring has a great advantage over commonly used Sliding Micrometer measurements because the monitoring does not interfere with the excavation procedure and provides continuous measurements. Practical experience using this new device in highly squeezing rock comes from the 57 km long Gotthard Base Tunnel in Switzerland, where convergence from 0.5 up to 0.7m regularly occurs in a controlled manner during excavation of the 13m diameter twin tunnel.

Since more then 25 years the Sliding Micrometer and the TRIVEC borehole instruments have been very successfully used for different applications in geotechnical engineering projects to measure profiles of deformation and displacement in soil, rock and in concrete structural elements. The wide range of applications covers landslide projects, foundation engineering, projects with retaining walls, deep excavations, soil consolidation, dam and dam foundation and also tunneling and caverns engineering. One application is the monitoring of the behavior of the Emosson double arch dam foundation since more then 20 years by TRIVEC. Another example are large scale static pile load tests for a new football stadium in Zürich including deformation measurement along the pile but also in the soil under and next to the piles. Recently, the Sliding Micrometer and the TRIVEC were redeveloped with new characteristics including digital sensors, new data acquisition system and new hardware.

This paper deals with the phicometer test, a new methodology for soil exploration for determining soil parameters. While the pressuremeter test provides direct information about the soil stiffness in terms of the Ménard Modulus and indirect information about the shear strength in terms of the limit pressure (Ménard 1957, Gambin 1995), the phicometer test yields directly the shear strength by means of the phicometer friction angle φ_i and the phicometer cohesion c_i. As it is shown in this paper, it represents an economic and efficient instrument with respect to subsoil exploration especially for large-scale explorations like for infrastructure constructions.

Load monitoring of support struts in temporary excavations plays a crucial role in confirming the stability and safety of the excavation. Data gained provides valuable feedback for the design engineer to facilitate refinement of future designs. Much of this monitoring is undertaken by strain gauges, sensitive instruments attached to the temporary supports, which are then linked to automated alarms through real time systems. The success of the monitoring is directly linked to the performance and interpretation of the data derived from the strain gauges, and the reliability of the real time system. There are a number of factors which can interfere with the performance of the monitoring system, to successfully and usefully interpret the data, the influence of these factors needs to be understood. The emphasis must be on the production of high quality data that can be reliably processed and rapidly given to the end-user, such that erroneous readings are minimized and genuine load changes are identified for interpretation. Through a number of case studies of deep excavation projects in Singapore, influences on the monitoring system are reviewed, their potential impacts discussed, and recommendations given to produce a high quality and reliable monitoring system.

In order to gain some insight into the origin of noise of the automatic In-Place Inclinometer (IPI) measures at the Castelrotto landslide (Italy) a number of tests were carried out in the laboratory and in the field. The field tests involved: 1) measurement of the excitation voltage at the IPI position; 2) analysis of a steady electronic signal. Laboratory tests analyzed: 1) the type of excitation effects on the signal when changing the power system; 2) the effects of modes of acquisition when changing the frequency of acquisition and the warm-up time; 3) the effects of temperature when heating each component of the acquisition system. It was found that a) the most noise comes from the electrical connections, and b) temperature significantly affects the signal, by reacting mainly on the electrical links.

This paper discusses procedures and problems associated with the installation of up to nine (9) electrolytic tiltmeter sensors in twelve separate casings to remotely monitor the shoring of two deep excavations at the New Natomas and the South River Pump Stations, in Sacramento, CA. The paper discusses the installation and monitoring procedures. It details some of the problems that were encountered during the setup and monitoring periods, both logistical and operator induced. The attempts to address the problems, whether successful or unsuccessful, are discussed. The paper concludes by addressing our ability to overcome these problems and meet our objective to use the data collected to monitor shoring stability, identify construction related issues and alert the contractor to potential problems in near real time.

The concept of using liquid level as a measuring device has been known for thousands of years in engineering and construction. Today, pressurized and open-channel liquid level systems are used to measure differential vertical movement of engineered structures. This paper presents a review of the two types of liquid level systems in use and discusses the pluses and minuses of each type. The authors present examples of their own experience with open channel systems.

This paper provides a state of the art overview of vibration based measurement systems used on vibratory roller compactors to continuously measure soil properties during and after earthwork compaction. The European community initiated the development of roller integrated measurement and continuous compaction control (CCC) over 30 years ago. Roller measurement values have since evolved towards the estimation of more mechanistic soil parameters, e.g., stiffness, modulus. Independent assessment of these measurement values has proven their efficacy.

An optical fiber strain sensing technique, based on Brillouin Optical Time Domain Reflectometry (BOTDR), was used to obtain the full deformation profile of a secant pile wall during construction of an adjacent basement in London. Details of the installation of sensors as well as data processing are described. By installing optical fiber down opposite sides of the pile, the distributed strain profiles obtained can be used to give both the axial and lateral movements along the pile. Measurements obtained from the BOTDR were found in good agreement with inclinometer data from the adjacent piles. The relative merits of the two different techniques are discussed.

Up-hole time domain reflectometry (TDR) devices that interrogate passive mechanical transducers are advantageous for engineering monitoring in situ. This technology is based on transmitting an electromagnetic pulse through a coaxial cable connected to a sensing waveguide and watching for reflections of this transmission due to changes in characteristic impedance along the waveguide. Depending on the design of the wave guide and analysis method, the reflected signal can be used to monitor various engineering parameters. This paper introduces some recent developments to improve the understanding and extend the usefulness of TDR technology. TDR waveguides for engineering monitoring are grouped into three categories according to the sensing principle, namely interface type, crimp type, and dielectric type. New design concepts and data reduction procedures for each type of waveguide are introduced. These developments improve and lead to a variety of transducers, such as water level, deformation, rainfall, scouring, soil moisture, sediment concentration, and electrical conductivity. The versatility and merits of TDR are highlighted by examples of hybrid economical TDR monitoring systems composed of a single TDR device and multiple sensing waveguides.

Geotechnical applications of time domain reflectometry (TDR) are continuing to evolve and usage is increasing, particularly for monitoring subsidence over active and abandoned mines and monitoring slope movement. It has evolved into real time monitoring with alarms and a variety of notification schemes. Fully automated systems have been installed which detect when measured values have exceeded specified magnitudes and/or rates, and initiate phone calls to responsible parties. Management must begin by deciding what critical measurements must be made, how frequently, what magnitude or rate of change defines an alarm condition, and what the plan of action is when these values are detected and verified. As a system is brought on line there must be an adjustment of the sensitivity, and refinement of the verification procedures to reduce false alarms to an acceptable rate of occurrence. Ultimately, the feasibility and reliability of an alarm system is critically dependent on the availability of well trained, competent, and committed personnel. These parties evaluate the measurements and make decisions relative to implementation of the next step in the action plan which may change as project personnel gain experience. The intent of this paper is to provide a broad overview of what has been learned over several years in development and implementation of alarm systems based on geotechnical monitoring with TDR technology.

The paper describes the use of optical fiber Brillouin Optical Time Domain Reflectometry (BOTDR) to monitor the strain distribution in an existing tunnel while a twin tunnel was bored at close-proximity. The twin circular bored tunnels between Serangoon and Bartley stations on the new Circle Line Stage 3 subway in Singapore were constructed at close-proximity to avoid underpinning the foundations of adjacent buildings. The minimum clear separation of the two tunnels is 2.3m (0.4 times the tunnel diameter). The Outer Tunnel was constructed first, followed by the Inner Tunnel, with the earth-pressure balance tunnel boring machines maintained at a minimum of 100m apart. In this trial application of BOTDR, the strain distribution along the Outer Tunnel was measured, in order to monitor its deformation due to the boring of the Inner Tunnel at close-proximity. The aim of the trial application was to determine the practicality of this monitoring method for future use in `live' tunnels. This paper compares the measurements obtained from optical fiber BOTDR with conventional methods of tunnel monitoring and describes preliminary installation and workmanship guidelines derived from lessons learnt during this trial.

Scour contributes to most failures of highway bridges constructed over waterways in the United States. Sediments are washed away by floods and bridge piers are left inadequately supported. Field monitoring of bridge sour process is necessary to study the scour mechanism, to improve the bridge piers and abutments design, to plan an effective remediation measure, and to develop emergency warning systems. The current tools for bridge scour monitoring are generally not satisfactory for these purposes. This study introduces the development of an automatic scour monitoring system using Time Domain Reflectometry (TDR). After briefly present the theoretical bases of TDR for scour detection, a framework for TDR information analyses is developed. Simulated scour and sediment tests were performed with TDR instrument deployed to acquire signals. The acquired data were analyzed using the developed theory. It was found that TDR signal changes have strong correlation with sediment layer thickness changes, as predicted by the theory. From TDR measured apparent dielectric constant and electrical conductivity, the depth of scour were accurately determined.

Recent research indicates that Time Domain Reflectometry (TDR) is becoming capable of identifying soil types in addition to providing water content and density. The process makes use of measured apparent dielectric constant and reflected pulse area, a new concept that captures characteristics of the reflected wave from the embedded probe. The method is relatively calibration free. This paper briefly describes the method and presents a new technique for representing the TDR signature to determine both the apparent dielectric constant and pulse area. The paper also incorporates recent findings with regards to probe geometry on measured electrical conductivity. The fitting is accomplished using the sum of two coupled functions: one is a non-linear hyperbolic function to model the reduction in voltage associated with the reflection from the soil surface and the other is an inverse trigonometric function to model the voltage from the reflection from the end of the probe. The model provides an excellent fit for TDR signals passing through homogeneous materials within the probe.

An instrumented test pile cluster was installed at a bridge reconstruction site in Newbury, Massachusetts, for a research program investigating long term time dependent pile capacity gain.. The pile cluster consisted of (i) three heavily instrumented test piles, (ii) a surrounding ground piezometer field, (iii) a static load testing frame, (iv) soil and surface acceleration and total pressure instrumentation, and (v) an on-site data acquisition array. A wide variety of data measurements and instrument types were used within the cluster, requiring several data acquisition systems that were combined into the on-site data acquisition array. The data acquisition array continually monitored the various types of gages permanently installed within the test piles and surrounding soils over the course of a testing program that lasted 20 months. In addition, temporary instrumentation, such as flat blade dilatometers and soil accelerometers, were also monitored by the data acquisition array for discrete periods over the length of the testing program. The paper describes the instrumented test pile cluster components and details the design and setup of the data acquisition array. The performance of the onsite data acquisition array is evaluated and lessons learned over the course of the project concerning the data acquisition are presented.

Surveillance of large geotechnical projects requires autonomous collection of data from a wide range of instrument types. An equally large range of data formats are employed by these measurement systems. A data exchange protocol is needed to make field data available for interpretation on a variety of platforms. This paper presents the results of the development of a robust Internet-enabled framework for the exchange of engineering data. Internet-enabled data exchange technology provides a standard for engineering data acquired from any combination of instruments by autonomously parsing data into a searchable database for archiving and distribution. A set of strategies and software have been deployed to create layers of abstraction that allow data files from different commercial and in-house data acquisition packages to meet standards for timekeeping, archiving, and data display. The data are stored in an Internet-accessible database and distributed to stakeholders via a password-protected Web site. The data exchange abstractions in this system allow it to be employed with an extremely wide variety of sensing techniques and data types, and the storage of data in a relational database rather than flat files provides for improved scalability in the types and volumes of data to be interpreted. These technologies have been employed in the continuous remote monitoring of a number of facilities over the past seven years.

It is common in earthquake engineering research to perform ad hoc checks on a theory by showing that it reasonably matches an insufficient experimental data set. Dense sensor arrays provide the ability to study the physics of composite material behavior through measurements of the spatial variation in dynamic response, rather than inferring the physics from a few select measurement points. The number of instruments used in an experiment is limited, however, by the cost of instruments and signal conditioning. The number is further limited by the effort required to run cabling to each sensor on highly-instrumented experimental structures. At UC Davis we have developed miniature data acquisition systems that can be mounted in a centrifuge soil model to reduce the number and complexity of signal wires emanating from highly instrumented experiments. The WiDAQ Wireless Data Acquisition System was developed as part of the NEES construction award at UC Davis. It is now in continuous use by researchers at UC Davis.

Miniaturized, multiple position, multi-hop, wireless instrumentation is now a reality and this paper describes development and testing of such a system to monitor crack response. These wireless systems will facilitate measurement of crack width changes in structures in order to assess structural health of critical infrastructure components such as fracture critical bridges or structures near construction. A low power consumption potentiometer displacement transducer and multi-hop communication algorithm allow this system to operate up to a year with 2 AA size batteries. The system described herein is capable of measuring long-term crack displacement along with temperature and humidity. A field test of the system is described that includes operation of multiple, remote data motes as well as back casting communication necessary to autonomously display crack response in a graphical format over the Internet. This system in another form won third place honors in the 2005 Crossbow Smart Dust Challenge, which represented the best executable ideas for wireless sensor networks that demonstrate how it is used, programmed and deployed to positively impact society.

The 3DeMoN (3-Dimentional Deformation Monitoring Network) monitoring system is a remote monitoring platform developed with the aim of offering a systematic and comprehensive approach to the solution of many environmental and civil engineering surveying and monitoring tasks. It integrates conventional measurement techniques and sensors (e.g. GPS receivers, Laser distance meters, Thermal Imaging Infrared Camera, etc.) with lowest power semiconductors, solar power supply, wireless communication, advanced database systems and Internet, with the aim of providing a unified management and view of remote monitoring data. This paper introduces the functional principles of this monitoring platform, presents its principal measuring technologies and illustrates the main characteristics of the latest developed and integrated instrument called ROBOVEC, a measuring unit based on a laser distance meter and a bi-axial modular robotization for horizontal and vertical movements. The first pilot installation on a landslide in Switzerland as well as the first monitoring results are presented.

A laser-based system for remote non-destructive inspection of concrete structures has been developed. The system is intended for the location of inner flaws in concrete structures, mainly in concrete transportation tunnels. The technique is based on the initiation and detection of standing Lamb waves in concrete layers. Vibration in concrete is initiated by laser impact provided by a pulsed Nd:YAG laser operating at wavelength of 1064 nm. A CW Nd:YAG laser radiation of 532 nm wavelength is used for detection of initiated vibration. The detection is performed with the use of a laser photorefractive interferometer. The interferometer uses principles of dynamic holography via two-wave mixing in photorefractive crystal and homodyne detection. A photorefractive crystal — Bismuth Silicon Oxide (BSO) — is used as a nonlinear medium for the recording of the dynamic hologram. Concrete samples examined in the laboratory experiments reproduce real concrete material used in transportation tunnels. Detection of various types of inner defects like voids, slits and honeycombs has been demonstrated. Accuracy of defect location is better than 2 cm. A mobile model of the system has been assembled and demonstrated in the field conditions.

This paper describes the development and deployment of a modular, remote wireless sensor monitoring system and its initial deployment for monitoring railway track performance on a busy high speed Amtrak Northeast Corridor line. The monitoring platform addresses some of the challenges faced by remote system applications; cost factor, power consumption, remote data transfer, storage and processing, and modularity. The remote sensor network consists of a) on-site sensor mesh, b) on-site base station, and c) data server in the headquarters. The on-site sensor mesh consists of sensors (e.g. strain gages, temperature) interfaced to motes. Data from the sensor mesh are conveyed to the base station and to the data server near real time at MIT via GPRS wireless Internet connection. The collected data are automatically stored in a database and can be accessed by any user equipped with an Internet browser and password. This paper includes results from this on-going deployment and provides an update on the capabilities of wireless sensor networks for long term and near real-time monitoring.

Presented in this paper is a wireless sensor network capable of large scale deployments for remote monitoring of geo-structural systems. The Wireless Sensor System (WSS) developed at Clarkson University allows for real-time, high-rate wireless data collection from an array of different sensors, including extensometers (strain gages) and accelerometers. The sensor network offers an economic solution for demanding large-scale monitoring applications, common in civil engineering. The developed wireless sensor network affords dense sensor deployments for distributed monitoring to provide insight into both the geotechnical and structural response of an entire system. This paper presents the capabilities of the wireless sensor network along with preliminary results from a field deployment of the system on a single-span integral abutment bridge in which real-time wireless data from an array of accelerometers was collected simultaneously with strain transducers through a single sensor network.

This paper will describe the technology that enables autonomous collection and Internet display of measurements from a wide variety of geotechnical sensors. In order for continuous monitoring to be economical, data must be collected without travel to the site, and ideally with no human intervention. Northwestern University's Infrastructure Technology Institute (ITI) has developed and deployed several techniques for the effective continuous remote monitoring of geotechnical facilities, all of which employ the same Internet display. These techniques include systems for control, data acquisition, and power management of instruments in the field as well as methods for data distribution and display. These technologies are readily adapted and scaled to sites ranging from a single-family home to projects covering entire city blocks. The case studies described herein include monitoring sinkhole-like subsidence on a Florida highway, monitoring soil movement adjacent to deep excavations in downtown areas of two major cities, and monitoring the effects of mine blasting vibration on a house in Kentucky.

During the construction of urban excavations, instruments are installed to monitor ground response to various construction activities, to verify design assumptions and to effectively apply the observational approach. Data collected from these instruments are also used in inverse analyses to develop improved soil models suitable for representing soil response during excavation. This study examines the relationship between various instruments typically used on an excavation project and the quality of information that can be extracted for excavation modeling. A synthetically generated set of instrument measurements using an idealized soil profile are used. Instrument readings considered include inclinometers placed in the support wall and in the retained soil, surface settlement points, extensometers, heave gages, piezometers and strain gauges in the bracing system. Various combinations of measurements are used in a novel inverse analysis approach, SelfSim, to extract the soil behavior. The study shows that in addition to the measurements of lateral wall deflections and surface settlement, measured forces in the struts significantly improve the quality of the extracted soil behavior and the overall predictive capability of the model. Inclinometers placed some distance behind the wall also improve the predictive quality of the model especially small strain soil non-linearity and provide some redundancy to measured settlements.

When an active creeping landslide is constrained by a retaining structure, it has "nowhere" to go and its downhill movement in the vicinity of the structure may be even reversed (provided the anchor forces are sufficiently large). This intuitively implies that the landslide has been stabilized. However, because the landslide is slowing, the viscous part of the shear strength on the sliding surface may decrease, eventually leading to increase in compressive stresses in soil in front of the structure. If these stresses exceed the passive earth pressure, this can ultimately lead to a failure and the landslide will simply "overflow" the structure. In this paper we propose an inverse analysis procedure for a long-term stability analysis of such a landslide. The procedure is based on the curve fitting of the observed displacement data and back-calculation of earth pressure changes from retaining wall deflections measured using a TRIVEC system. Its application is illustrated on an example of the landslide stabilization project in Combe Chopin, Switzerland.

In the practice of the preloading method for soft ground improvement in construction management, field monitoring of ground behaviors induced by overlying fill is an important factor. Also, field engineers need information on the ground properties of the site and on the construction works. Integrating all information into one database can provide a more efficient way for managing and utilizing the data for construction management. In this study, an integrated system for construction management of a ground improvement site under preloading is developed. The database of all collected information is the backbone of the system. Various functions on managing and utilizing information in the database are also included pre- and post-data processing with graphic visualization of the output, spatial data interpolation, and prediction of ground behavior using field measurement data. By providing integrated information and predictions over an entire project area with comprehensible visual displays, the applicability and effectiveness of the developed system for construction management can be confirmed.

On site investigations are conducted in a deep (180 to 280 m) clay layer in Belgium since 1980 to study its potential as a host formation for a disposal facility for high-level radioactive waste. The clay environment requires all underground openings (shafts and galleries) being lined. A proper understanding of the porewater pressure and total stress evolution is essential for the safe and economical design of these linings. Porewater pressure measurements have been made since more than 20 year, mostly through multifilter piezometers. They give a detailed record of the short- and long-term evolutions due to construction activities (mainly excavations). Total stress observations, which are less straightforward to perform, have been made through a large range of techniques, varying from visual observations at the excavation front over pressuremeter tests up to long-term stressmeter measurements. These observations have largely improved our understanding of the phenomena in this particular medium, which behaves under some circumstances as a rock (e.g. fracturing), and under other circumstances as a soil (porosity and two-phase flow). This paper focuses on the measurement techniques applied, their performance in the field, and the associated measurement results that have been obtained. Further we show how these data have improved our knowledge of this clay medium. Feedback of the measurements into the hydromechanical models also has improved their reliability and versatility, so that they are being used to obtain safe and economical designs.

Monitoring data often need deep analysis in order to understand the real behaviour of a structure or a soil mass which may be overshadowed by unknown phenomena or boundary conditions. Temperature is one of the most common parameters which affect field measurements and create problems in data interpretation and use. The present work introduces a statistical approach for better understanding the behaviour of the monitored phenomena, reducing the uncertainty associated with the measurements and detecting possible anomalies in the monitoring system. The approach is described with reference to a specific application on a cable stayed bridge. In order to describe the dynamics of the bridge in normal conditions, a state space model is proposed. Then, a hierarchical multivariate detector (HMD), based on a Multivariate Exponentially Weighted Moving Average control chart (MEWMA), is introduced for analysing the behaviour of the monitoring system when one or more parameters change. Using appropriate threshold values, the HMD is able to check the tendency of the system to change its status from a safe situation to a warning or alert one and to localize the source of variability. In order to show its ability to detect anomalies, some simulation examples are provided.

The handling of data in geotechnical and environmental datalogging applications is quite different from typical industrial data handling. This is partly because industrial users are most interested in the present situation while researchers often value long and uninterrupted series of measurements. There is, however, increased interest to incorporate the best parts of industrial systems into geotechnical datalogging applications, namely database storage, visualization of data, alarm services, web service and the latest communication and interconnection technologies between software applications using open standards. The purpose being to cut the cost of data handling and reporting, perhaps as much as 80% compared with the older tabulated data handling, while giving new meaning to the word "logged data".

Described in this paper is the use of an Automated Motorized Total Station (AMTS) for 18 months to monitor potential movement of buildings around a deep excavation in rock. The approximately 24.4-meter deep excavation is for a new high-rise building located in Manhattan. The AMTS was installed on top of an adjacent building in the vicinity of the excavation, with four mini-prisms acting as backsights. More than 30 mini-prisms (targets) were installed, in a few rows, on three buildings abutting the excavation. The AMTS was set up to read distance, azimuth (bearing of line-of-sight), and angle from the horizontal (of the line-of-sight), each hour for the duration (18 months) of the excavation and building construction to street level. The data that we have collected include: target coordinates — calculated by a proprietary software — based on measurements of the AMTS, temperature at AMTS location for a few weeks, distance from AMTS to the targets, our estimate of potential movement of the buildings involved due to periodic change in temperature, and accuracy of AMTS in distance and angle measurements as reported by the manufacturer. A summary of the most likely magnitude of errors, which contribute to the calculated coordinates of survey targets, and partial details of the closed-form solution, will be presented. Recommendations for future research are also provided.

Automated Motorized Total Stations (AMTS) also known as Robotic Total Stations have now been utilized for monitoring industrial applications, and deformation of various civil structures for approximately seven years in the United States and eighteen years throughout the remainder of the world. Their use although not yet common place is becoming more extensive on both large and small projects as experience grows and practicing instrumentation professionals better understand their benefits. In this paper the authors will provide ten of the uses of AMTS for the monitoring of deformation of civil structures from across the United States. Although tunnel related projects have historically benefited the most from AMTS, examples of AMTS use in bridge construction, tall building thermal deformation monitoring, small private underpinning and railroad monitoring will be discussed. This paper will provide the practitioner a familiarity with currently available, practical uses of AMTS, database software, system power techniques and remote telemetry.

For the development of Ramsey Town Center, which is a large commercial and residential development north of Minneapolis, Minnesota, additional stomwater conveyance capacity was needed, requiring the design and installation of one 60-inch and two 54-inch diameter storm water pipes under an active railway embankment. The storm water pipes were to be installed in steel casing pipes with diameters (ID) of 86-inch and 78-inch respectively. These three casing pipes were installed under the two-track railway embankment by employing pipe ramming methods. An embankment monitoring system consisting of 74 mini prisms, mounted on the tracks and jacking pit, and a Leica automated theodolite located adjacent to the track, were installed several weeks prior to the ramming operations to monitor embankment movement during the operations. The monitoring system was fully automated with Internet access to real time data plots. The cost of the installation of monitoring system and performance of continous monitoring with daily reports for a four months period was approximately $90,000.

This paper provides a synopsis of the state of practice of manual total station movement monitoring. Different variables such as instrument used, accuracy under varying and challenging conditions, sources of error, establishment of accurate baseline readings, set-up and control of survey networks, and reporting, distribution and archiving of data are examined. A specific project located in downtown Toronto provides an example of practical and technical aspects of precision survey monitoring. The excavation for the project was seven-stories deep and occupied an old, open parking lot next to several sensitive and/or significant buildings. Sixty-five targets placed on surrounding structures were monitored with a total station theodilite. Inclinometers, crack-gauges and preconstruction condition surveys of abutting structures were also part of the monitoring for the excavation portion of the project.

Electrolevel and accelerometer beam sensors are now commonly used to measure settlement of foundations and tilt of walls. They are even being installed in tunnels to assess distortion, despite beam systems having the fundamental limitation in that they only measure deformation at right angles to the beam alignment. Many clients are also choosing to abandon the continuous beam chain scheme in the quest for cost saving and are adopting a place one, miss one scheme. This paper shows this to be a false economy. This paper summarises the properties of electrolevels and accelerometers and then explores the basic geometry of beam based monitoring systems, based on the commonly installed electrolevel units. As a continuous chain the data are accurate and reliable and can provide a clear picture of settlement deformation. An example of the settlement of a 32m long basement wall is presented and the effect of adopting non-continuous chains is illustrated. The serious loss of detail and difficulties in interpretation are highlighted.

The publicity for this symposium indicates that papers for Theme 3, "The Business Side of Instrumentation", should address this topic by demonstrating and quantifying the benefits of field performance monitoring to owners, project management teams, engineers, construction contractors, regulators and insurers. This paper takes a different view of the business side of instrumentation. After a brief reference to some of the benefits, the paper focuses on the following question: How do we in the FMGM (Field Measurements in Geomechanics) community do a better job of promoting our business of manufacturing and providing field services? This paper reviews the current FMGM organization and some views expressed at previous FMGM symposia. Following this introduction we have tried to put forward some ideas that we can follow individually for promoting the business of the FMGM community. Because the quality of our work impacts on our future business, in appropriate sections we have described and referenced various publications that are intended to guide us in maximizing the quality of what we do.

With the construction of large publicly funded infrastructure improvements by public transportation agencies, instrumentation and monitoring contracts in New York City have grown significantly since 2005. Part I of this paper will introduce four large NYC infrastructure projects including South Ferry, East Side Access, the Fulton Street Transit Center, and the 7-Line Extension. These projects and others including the Second Avenue Subway have resulted in a shift in the complexity, scope and procurement of instrumentation services in the metropolitan area. Part II will focus on the lessons learned in developing cost bid proposals and consider the state of current specifications, the technician's role, the impact of minority, disadvantaged or women owned business enterprises, the risk bidders absorb to compete in this market, and the trickle down effect of these large projects on smaller projects. We will examine our approach and our intention of providing improved data interpretation and evaluation. The expansion of the market comes not without the issue of balancing performance against cost, with risk and value being underlying components.

The scope of this paper includes a description of a relatively inexpensive settlement profiling instrumentation system that was used to monitor large settlements (>15 ft) anticipated under service loading conditions. Importantly, the paper also describes the invaluable data that was obtained by the system while monitoring the compressibility of a 60-ft deep deposit of municipal solid waste (MSW) subjected to vertical loading imposed by a 10.4 acre test fill that was as much as 30-ft thick. The horizontal settlement profiling instrumentation system was developed to compliment conventional surface and buried settlement plates by facilitating settlement evaluations at 1-foot horizontal intervals along four transects at the base of the test fill, each more than 650 ft in length: The waste compressibility information captured by this system allowed designers to advance an innovative design concept that was ultimately permitted as the first vertical expansion of a MSW landfill over unlined waste by the Tennessee Department of Environment and Conservation (TDEC). This paper focuses on the development of the settlement profiler instrumentation system and provides a discussion of the primary and secondary waste compressibility results from the test fill. Valuable lessons learned regarding the instrumentation system are also reported.