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ADAS (Automatic Data Acquisition Systems) are electronic devices used to automatically read, store and transmit measurements from geotechnical, environmental and structural sensors used for monitoring dams and levees. Because of the specificity of the conditions of their deployment in outdoor, spread-out and sometimes harsh conditions, ADAS used for those applications need to have a number of features and functionalities which are discussed in the paper. The paper will be limited to ADAS for monitoring static measurements, as opposed to systems for dynamic measurements such as accelerations due to earthquakes. Low power consumption, robustness, modularity, ease of deployment, diversified network configurations between units such as line , star and tree networks, a wide variety of telemetry options such as radio and cell modems are all features that are essential for a successful deployment in the field. The paper covers the features that are nowadays mainstream on available solutions for ADAS for dams and levee monitoring, including discussions on network configurations, power supply options, network access options and real-time monitoring. The advent of low-power low-cost radios that open the possibility of eliminating all surface cable runs on dams and levees is also discussed.

Sensitivity analysis involving different random variables and potential failure modes of cantilever sheet pile walls for different soil conditions focuses on the fact that, high sensitivity of a particular variable on a particular failure mode does not necessarily imply a remarkable contribution to overall failure probability (Pf). The present paper aims at identifying a probabilistic risk factor (Rf) for each random variable based on the combined effects of Pf of each mode of failure and sensitivity of each random variable on these failure modes. Three different soil conditions are considered: (1) cohesionless soil above and below dredge line, (2) cohesionless soil above dredge line and cohesive soil below dredge line and (3) cohesive soil above and below dredge line. It is observed that friction angle of both foundation and backfill soils are the major guiding factors for Case 1, while for Cases 2 and 3, cohesion for foundation soil dominates over the other two random variables. Thus the present paper proposes a safe and economic design by assigning different Rf for different random variables for sheet pile walls embedded in different subsurface conditions and varying positions of water table.

When estimating the time-rate of settlement for foundation soils treated with vertical drains, understanding the horizontal drainage behavior of the soil is important because the time of consolidation settlement may be critical to the overall construction schedule and sequencing. This paper explains the process for obtaining the horizontal properties of soft soils in the laboratory using a Rowe cell, a laboratory device that directly measures the horizontal drainage of soft soil samples through a radial consolidation test. The Rowe cell further allows for back-saturation of test specimens and the ability to replicate in situ lateral stress conditions with an applied cell pressure. This paper summarizes how challenges associated with specimen preparation, test setup and procedure, and data analysis and interpretation can be overcome. Finally, this paper demonstrates that this is a viable method that should be considered more often for obtaining horizontal drainage design parameters.

Ground-source heating of bridge decks can be an alternative to the use of salts and chemicals to deice bridge decks. Energy foundations, geothermal boreholes, shallow trenches, or the approach embankment can be utilized as energy storage media and heat exchange pathways to utilize the ground as a heat source. Coupling the energy foundation with a ground-source heat pump can provide higher inlet fluid temperatures and result in more effective bridge heating but at the expense of greater energy consumption and increased system complication. Circulating the fluid directly from the energy foundation to the bridge deck relies heavily on the in situ ground temperatures. This paper outlines the operational principles and how these are related to the design parameters of bridge-deck deicing systems. A series of parametric analyses was performed to investigate the bridge-deck heating process. The analyses considered a variety of tube spacings, inlet fluid temperatures (i.e., ground temperatures), flow rates, wind speeds, ambient temperatures, and thicknesses of concrete cover over the circulation tubes. The results serve as a benchmark to gauge the operational conditions and the energy requirements for designing ground-source bridge deck deicing systems. Ground temperatures serve as a baseline for heating of bridge decks with passive heating in the winter, and this study underlines its limitations at colder environments. This can be overcome by collecting heat from the bridge deck in the summer and injecting the collected heat into the ground to raise the ground temperatures. This stored energy can be reclaimed in the winter when needed. The issues related to heat collection and ground storage are part of a broader study and fall outside the scope of this paper.

This paper discusses the practical aspects of preparing Geotechnical Baseline Reports. Guidelines for the preparation of Geotechnical Baseline Reports were established in the ASCE publication entitled, “Geotechnical Baseline Reports for Construction,” dated 2007. However, the practical aspects of actually writing a Geotechnical Baseline Report and the risk assumptions associated with this document are highly controversial. Not every project needs a Geotechnical Baseline Report and not every geotechnical engineer is equipped to write one. This paper will provide its own set of guidelines for the preparation of Geotechnical Baseline Reports. The paper suggests that Geotechnical Baseline Reports are one contractual format for handling such as third party impacts and differing site conditions that often arise when involved with subsurface construction.

This paper describes a study of the behavior of a group of piles under impact loading. Many structures such as bridge piers, offshore platforms, or berthing foundations can be subjected to the horizontal impacts from ships during their lifetime in which the system failure would have serious consequences. Guardrails for road side safety are another type of impact-resisting system that are extensively used and have a direct relation to human life and cost. Moreover groups of piles can serve as an efficient and relatively cost-effective protective structure around critical and important facilities. Prediction of the system response during the impact can lead to a more effective and economical design. There has been a very limited amount of experimental work on lateral response of group piles under impact loading in particular in the field of full-scale tests. This paper describes a full-scale field test performed on a group of eight side-by-side piles embedded 3 m in a loose sand to sustain an impact of a 6800 kg truck with an approaching velocity of 80 km/h. The instrumentation includes accelerometers on the truck, strain gauges on the posts, and high-speed cameras to capture the deflection. The eight posts and the connector beam have been simulated using an advanced numerical simulation software LS-DYNA (Livermore Software Technology Corporation) to characterize the features of the soil-pile-beam interaction under impact and improve the design methodology.

Bridge scour is a major cause of damage to bridge foundations and abutments. Approximately 17,000 scour-critical bridges exist in the United States. Scour-critical bridges are bridges with foundations that are unstable for calculated and/or observed scour conditions. This designation comes in part from the use of overconservative methods that predict excessive scour depths in erosion-resistant materials. Other available methods capable of overcoming this overconservatism are relatively uneconomical because they require site-specific erosion testing. This paper presents the assessment of two bridge case histories using the observation method for scour (OMS). OMS is a relatively new quantitative bridge-scour assessment method that accounts for time-dependent scour depth using field measurements. This method, which does not require site-specific erosion testing, was developed as a first-order assessment method for use in combination with routine bridge inspections. OMS uses charts that extrapolate or interpolate measured scour depths at the bridge to obtain the scour depth corresponding to a specified future flood event. The vulnerability of the bridge to scour depends on the comparison between the predicted and allowable (threshold) scour depths. The case histories presented in this paper consist of two Texas bridges, one designated as scour critical and the other as stable by the Texas Department of Transportation (TxDOT). Both stable and scour-critical bridges were selected to test OMS and also compare it with TxDOT's scour designation. These case histories serve to demonstrate the validity and applicability of OMS to full-scale bridges and to provide practitioners with two potentially useful real-life case histories that could serve as examples for engineering practice. A validation process was performed on the two case histories using historical scour measurements and flow data. The validation exercise showed that there was good agreement between predicted scour depths using OMS and field measurements. OMS was then applied as a bridge-scour assessment tool to both bridges using the 100-year flood as the future flood and the outcome of OMS compared with the original TxDOT designation. As a result of this, the originally scour-critical bridge was found to be stable according to OMS. The bridge originally designated as stable was also found to be stable according to OMS.

In February of 2011 an earthquake event caused significant damage and loss of life in Christchurch, New Zealand. Such an event serves as motivation for improved foundation design and characterization of the shallow subsurface. In January of 2013, University of Texas engineers acquired surface wave data which has been made available to the ASCE GeoInstitute Geophysical Engineering Committee for a benchmark project. Participants were invited to process and interpret the common data set. This paper reports the results designated as those of “Analyst A”. The active vibroseis and sledgehammer data were combined to produce a composite Rayleigh wave dispersion curve. Alternative soil profile representations were considered. The resulting image is of low velocity zone sandwiched between a faster surface zone and a faster profile down to 30 meters depth. INTRODUCTION The UTexas1 SurfaceWave Dataset was acquired in Christchurch, New Zealand. The site was located approximately 1.5 km from the coast. The Geophysical Engineering Committee of the ASCE GeoInstitute has organized a benchmark project in which participating geophysical engineers have been invited to process and interpret this common data set with tools of their own choosing. The instructions were to work as much or as little of the data as each participant desired. The available data include both active-source and ambient noise sets. This participant has chosen to only work the active-source data. The vibrator data were processed in the frequency domain, the hammer data in the time domain. The resulting dispersion curves were then combined to provide a composite dispersion curve. Inversion of the composite dispersion curve was done employing a 1-D-gradational soil profile in which the objects of the inversion are control points whose depth and shear-wave velocity assignment may vary. The reader is referred to Michaels (2011) for another example of this representation. page 1 This is an author-produced, peer-reviewed version of this article. The final, definitive version of this document can be found online at Geo-Congress 2014: Technical Papers and Keynote Lectures, published by the American Society of Civil Engineers. Copyright restrictions may apply. doi: 10.1061/9780784413272.074

Over the past few years, intelligent compaction (IC) has been a focus of research, demonstration projects, and specification development in the United States. The Federal Highway Administration (FHWA) has recently moved IC to national level implementation. Equipment manufacturers, individual state departments of transportation (DOTs), and the Technology Transfer for Intelligent Compaction Consortium (TTICC), a Transportation Pooled Fund, TPF-5(233) initiative, are also focusing on implementation efforts. What this paper does is describe the results of a series of workshops attended by more than 400 attendees—representing several state DOTs, FHWA, equipment manufacturers, and researchers—that contributed to a detailed roadmap identifying implementation needs and action items. A key outcome of these workshops was the development of a prioritized list initially created in 2008 and updated annually through 2012. This paper describes in greater detail how this list was developed and prioritized and how it has changed since it was initiated in 2008. Accompanying this list is a set of action items to overcome the various barriers identified.

The use of drilled shaft concrete piles is generally not a widespread method of stabilization of landslides along Alberta highways as a result of perceived high costs and the uncertainty of performance of these structures in the long term. However, over the last 30 years, the use of drilled shaft piles has been the preferred method of stabilization of various sites where conventional methods were not feasible either because of site constraints or not considered appropriate. This paper presents a case history of a roadway embankment slide for which the most appropriate remedial measure was determined to be the use of a tie-back drilled shaft concrete pile retaining wall as a result of the deep-seated nature of the slide, inability to relocate the roadway, and concerns over using a toe berm. Stabilized in 1997, the roadway and pile wall are still performing satisfactorily despite some observed roadway undulations and movements of the sideslope behind the pile wall. This paper addresses the details of the site and slide activity, the judgments exercised in deciding the locations and depth of the concrete piles, and the design and construction of the pile wall retaining system.

The presence of groundwater table (GWT) within a flexible pavement can have a pronounced detrimental effect on the mechanical response of its foundations and consequently on the structural performance of the pavement system as a whole. The related literature reveals that little work was done to rigorously model the impact of shallow GWT on the pavement's structural performance and investigate the sensitivity of this impact to the foundation's stiffness. In this paper, statistical factorial analyses were applied to numerical modeling to investigate the effects of GWT, foundations stiffness, and GWT-foundation stiffness interaction factors on the rutting of flexible pavements. A finite element model simulating the pavement foundations as nonlinear porous media governed by the Biot coupled behavior was set up first. The response of the model was evaluated for combination of design values of the GWT and foundation stiffness parameters each of which was defined at lower and upper levels (two levels-factorial design of experiments). Analysis of variance (ANOVA) method was then used to examine the effects of the factors analyzed on the pavement rutting. The analysis results showed that the GWT and its interaction effect with subgrade stiffness have significant influences on the pavement rutting. The detrimental effect of the GWT becomes more pronounced when the subgrade stiffness decreases, while such effect changes insignificantly with changing the stiffness of the granular base. The paper opens a new window for assessing the structural performance of flexible pavements under various GWT and foundation material conditions using the coupled finite element method in conjunction with the statistical factorial analysis approach.

Geothermal piles are increasingly used around the world as an innovative and sustainable method of harvesting shallow geothermal energy. Energy harvested through this technique can be used to partially meet the heating and cooling energy demand for residential and commercial buildings. Despite the growing recognition of the benefits of geothermal piles, the complex heat exchange through these piles is not yet fully understood. This paper describes a series of thermal tests performed on an instrumented model heat exchanger pile installed in a standard F50 Ottawa sand bed. Temperature measurements were obtained at different locations within the soil, on the pile surface, on the tank boundary, and at the inlet and outlet points of the circulation tube. Recorded temperature data are used to obtain time-dependent heat exchange efficiency of the model pile. The thermal tests presented in this paper provide valuable data on the nature of heat exchange through geothermal piles and on the thermal response of soil in the vicinity of a heat exchanger pile.

Micropiles are small-diameter grouted piles (typically of diameters less than 300mm). Micropiles are ideally suited for low headroom and limited work area conditions. Specially developed installation processes mitigate noise nuisance, vibrations to surrounding soils and structures, disturbance to the production operations in individual units, and disruption to the functioning of business locality, which makes micropiles suitable for underpinning and seismic retrofitting of structures. With a wide variety of potential applications, it is necessary to understand the behavior of micropiles under different loading conditions. Reliable experimental data on battered micropiles are rather scarce compared with that of vertical micropiles. This paper presents the results from an experimental study conducted to understand the response of vertical and battered micropiles with different length/diameter ratio (L/D) subjected to vertical and lateral loading conditions. The vertical load-carrying capacity was found to increase with increasing L/D ratio upto a 300 batter. The ultimate lateral load was found to increase significantly with increasing L/D ratios up to a L/D ratio of 30 and 48 for vertical and battered piles, above which the increase in ultimate lateral load for increasing L/D ratios was found to be insignificant. Furthermore, the ultimate load capacity and mode of failure of the micropiles is a function of the angle of batter, direction of batter, and the L/D ratio for vertically and laterally loaded micropiles. The details of the experimental model employed in the study and the associated failure mechanisms are described in this paper.

Geothermal energy is an increasingly demanding energy source in Europe and USA. Louisiana has a huge potential for geothermal energy. This paper describes the potential use of geothermal energy which can be extracted in Louisiana. In the paper, a 4-story building was chosen in New Orleans, Louisiana, which has a pile foundation with a total of 145 driven piles. A total of 16 energy piles from 16 pile groups were simulated in the analysis, and it is found that each 24.38 m-long single pile can extract a maximum of 1.83 (kW/hr) cooling load and 1.68 (kW/hr) heating load. Altogether, the 16 energy piles can give almost 19.9% of the total cooling demand and 68.12% of the total heating demand of the entire building. Further analysis was also done to compare the economic and environmental effects by gas, propane, oil, electricity and geothermal energy to heat/cool the building. If the total demand of heating and cooling is done by each of these energy sources, it is found that natural gas will be 13.6 and electricity will be 16 times more costly than geothermal energy. Moreover, natural gas and electricity will emit 1.8 and 1.7 times more CO2 than geothermal energy.

This paper describes wisdom of ancient engineering practice. The first wisdom is about a biology-based method for bridge-scour protection. A number of historical bridges across waterways in China served for more than 1000 years without significant structural damages. Protection provided by cultivated oysters is believed to be responsible for their excellent performance in scour protection. This offers a green approach to mitigate bridge scour. Another story is about natural hazard warning. A number of historical records indicated that major natural hazards are typically accompanied by abnormal behaviors of animals. The first successful prediction of earthquake occurrence is the Haining earthquake of China. The prediction and evacuation order was partially based on observed abnormal behaviors of animals. The paper also describes an innovative sticky-rick lime mortar used in ancient construction and bio-inspired sensors that potentially can improve existing understanding of bridge-scour mechanisms. In the authors' opinion, these historical heritages will continue to inspire emerging engineering practice.

Interfaces of soils with man-made materials play a major role in geotechnical systems, from deep and shallow foundations to landfills and retaining walls. Accordingly, it is of paramount importance to understand the behavior of interfaces involving different construction and natural materials. For soil-man made material surface interfaces, a linear increase in strength occurs with increasing surface roughness until the interface shear strength reaches that of the soil. Any subsequent increases in surface roughness result in no additional change of observed system interface strength. In this paper a series of laboratory axisymmetric interface shear tests involving axial and torsional loading are presented. This study involves interface shear tests between Cone Penetration Test (CPT) friction sleeves with different roughnesses and different sands. CPT sleeves with surface roughness ranging from that of the conventional smooth sleeve to those with texture elements of 1 mm in height are tested with sub-rounded and sub-angular medium sized sands. This laboratory study is part of an effort to improve soil characterization and pile design by means of the CPT that utilizes multi-sleeve modules. The next generation system expands the use of friction sleeves with different roughnesses to include response measurement under both axial and torsional loading.

Bridge scour is the loss of soil by erosion due to water flowing around bridge supports. Scour has been the number one cause of bridge failure in the United States with an average annual rate of 22 bridges collapsing or being closed due to severe deformation. The current bridge design code suggests engineers to use the resistance factor of 1 in the foundation design for extreme conditions. This paper aims to modify the resistance factor in the foundation design in the case of pier scour using reliability theory. First, a set of database is used to quantify the statistical parameters associated with the scatter between the predicted and measured pier scour depth and the probability that a deterministically predicted pier scour depth will be exceeded. The database is also used to provide the bias factors in current predictions. In the second part these statistical parameters are used to develop a reliability-based load and resistance factor design for shallow and deep foundations subjected to scour. The goal is to provide a design procedure where the reliability of the foundation is the same with or without scour.

Using shredded tires as an alternative backfill material for retaining walls is an effective method for recycling a common and abundant waste material. In this paper, the engineering properties of the shredded tire from various sources were compiled. Retaining walls were designed for static and seismic conditions using the average properties following load and resistance factor design (LRFD) method and compared with that of conventional granular material. The performance of retaining wall backfilled with shredded tires was then investigated by applying design earthquake acceleration-time histories using advanced finite element software and compared with that of sand backfill. Results show that the shredded tire backfill significantly reduces the wall tip deflection and maximum shear force and bending moment along the wall.

The resilient modulus (MR), which is a key parameter in the design of pavements, is significantly influenced by the seasonal moisture variations and the resultant suction fluctuations. Several relationships or models are available in the literature for predicting or estimating the MR taking account the influence of moisture content or suction. In this paper, two models from the literature are used for providing comparisons between the measured and predicted MR values of a fine-grained soil compacted at three different initial water contents. The strengths and limitations of the two selected models are discussed. In addition, a semi-empirical model is proposed for predicting the variation of the MR with respect to suction using the soil-water characteristic curve (SWCC) as a tool. The proposed model is promising and can be used in the reliable prediction of the variation of the MR with respect to suction.

Cut-and-cover construction is a soil-structure interaction problem involving staged sequences of installation and removal of bracing supports. The behavior of the retaining wall and bracing elements influence the earth pressures that act on the wall. Numerical modeling is a useful tool for optimizing the design of braced retaining wall systems because the various possible outcomes can be investigated by varying the geotechnical and structural properties of the elements for any situation. Proper understanding of the interactive behavior of the wall and bracing system will guide decisions for achieving an optimum design, both to control wall displacements and satisfy constructability requirements. This paper discusses the proper selection of soil and structural models, including considerations of nonlinear stress-strain behavior and time-dependent properties of soils, as well as the impact of groundwater seepage conditions on retaining wall behavior. A case study example is presented to demonstrate the process of modeling the complex interaction between the diaphragm walls and bracing elements for a subway station box using the software PLAXIS.

Determining the shape of the slip surface is an important step in the calculation of earth pressure on a retaining wall. Fundamental assumptions are made regarding the geometry of shear bands and slip surfaces in methods that are widely used in the analysis and design of retaining walls. Experimental visualization allows observation not only of how the slip surface develops but also how it evolves with wall movement and soil deformation. This paper presents results of experiments performed to study the formation of shear bands in sand retained by a flexible wall. Particular attention was paid to the effect of the initial sand density on the distribution of volumetric and maximum shear strains as a function of wall displacement. To achieve these goals, a small-scale test box was built to model a plane-strain condition for a retaining wall system. A model flexible wall was hinged to the bottom face of the test box. The wall was then backfilled with silica sand using the air pluviation method. The pluviator openings were such that different relative densities were achieved (Dr=15% and 77%). A displacement controlled mechanism was employed to apply outward displacement on the crest of the wall away from the backfill material to model an active-pressure mode of failure. The Digital Image Correlation (DIC) technique was used to observe shear band evolution with progressive outward movement of the wall. The results highlighted the suitability of this technique to visualize and characterize the formation of slip surfaces in laboratory-scale experiments.

Four geosynthetic-reinforced soil (GRS) piers, each built with different reinforcement strengths and aggregate backfill material, were constructed at the Federal Highway Administration's (FHWA's) Turner-Fairbank Highway Research Center in collaboration with the Long-Term Bridge Performance Program. The objective of the research is to assess the secondary deformation characteristics of GRS for load-bearing applications under service load conditions. The experiment consisted of axially loading the piers with 490 kN decommissioned prestressed concrete girders, resulting in an equivalent vertical applied stress of 200 kPa. The geometry of each GRS composite was 1.2 m square by 2.3 m in height, for an approximate base to height ratio of 0.5. The facing element for each GRS pier is a simple, split-faced concrete masonry unit (CMU) that is frictionally connected to the GRS composite at a nominal vertical reinforcement spacing of 0.2 m. The piers were instrumented to record reinforcement strain, earth pressures, and deformations. This paper will discuss the objectives of the experiment, explain the testing program, and share some of the vertical deformation results after almost four months in service. In addition, the results will be compared with the results of a long-term (since 1999) study on secondary settlement of a GRS abutment.

Recent archeological investigations revealed the use of a novel clay- based hybrid composite in some ancient Chinese structures. This ancient material technology uses lime, clay, sand, and biopolymers such as starch to prepare a hybrid clay based composite. Samples of this material obtained from an intact old tomb are remarkably tough, strong, acid resistant, and reportedly blast resistant. In this paper, we studied the chemical, nano-micro structural, and nanomechanical properties of this ancient material to explore the underlying physical and chemical mechanisms controlling the mechanical behavior. X-ray diffraction (XRD) results of pulverized sample indicate the presence of crystalline phases, mainly sand and silt inclusions, as well as amorphous phase, calcium-silicate-hydrate (C-S-H). Scanning/transmission electron microscope (SEM/TEM) images revealed a complex, highly heterogeneous microstructure consisting mainly of fully activated C-S-H binder, partially activated clay aggregates as well as dense nano-crystallites and intercalated nanocomposites. Statistical deconvolution of a massive volume of nanoindentation data suggests that the cementitious binder consists of five major mechanically different phases with elastic moduli of 5.7±2.6 GPa and 12.6±2.3 GPa, 22.3±7.4, 54.4±5.7 GPa and 83.2±17.9 GPa. While the two lower elastic moduli are attributed to pure clay aggregate inclusion and polymer-clay matrix, the third one resulted from low-density C-S-H gel, similar to those formed in ordinary Portland cement. Based on this study, we propose that slow and weak pozzolanic reaction between clay and lime produces cementitious binder consisting of C-S-H phase with an overall low packing density. Characteristic mechanical property of this hybrid composite is, therefore, attributed to the binding mechanism of C-S-H phase and nano-crystalline precipitates.

Increased acceptance of in situ stabilization/solidification (S/S) depends on its long-term effectiveness and field performance at contaminated sites. Field trials of deep soil mixing application of S/S were performed at a contaminated site in West Drayton, near Heathrow Airport, in the United Kingdom back in 1996. Core samples were taken from this site at 2 months and 4.5 years and tested. This paper addresses the leaching properties of the contaminated site soils at 17 years in comparison to the properties at 0.24, 2.4, and 5 years. Seven different cement-based binders were used, including cement, PFA, lime, and bentonite to the soils, which were contaminated with a cocktail of heavy metals and organics. Two leaching methods, toxicity characteristic leaching procedure (TCLP) and the BS EN 12457, were applied to study the leaching behavior of the heavy metals in stablized/solidified soils. The leaching test results showed that leachate pH decreased with time in the first 5 years and then leveled off at 17 years. The BS EN 12457 leachate concentrations were lower than drinking water standards, suggesting that the performance of the S/S at 17 years' service time is satisfactory. The leaching behavior of the heavy metals in these S/S soils was mainly controlled by the alkalinity of the binders, with some of these heavy metals being absorbed into calcium silicate hydrates (C-S-H) gel phases. The binding mechanisms within the applied cementitious binders may be dominated by their leachate pH, which correlated with their corresponding metal hydroxide solubility. © 2014 American Society of Civil Engineers.

This paper pertains to the influence of introducing geocell-reinforced granular fill beneath a footing overlying soft soil. Extensive laboratory investigations are available to understand the behavior of geocell reinforcement for footings under various subsoil conditions. Several numerical investigations have been carried out using foundation models to understand the behavior of geosynthetic reinforced granular layers. Existing literature has minimal discussion on analytical modeling of geocell reinforcement. A simple and easy approach to develop a general understanding of the behavior of footings on geocell-reinforced soils would be to consider the contact pressure distribution of the geocell-reinforced bed. Three types of variations of contact pressure distributions, that is, uniform (for short geocell), linear (for intermediate width geocell), and exponential decay (for wide geocell), were considered. The present study investigates the response of strip and circular footings on geocell-reinforced soil. The ultimate bearing capacity of the footings is estimated using Terzaghi's approach based on the general shear failure mechanism. The present analytical model was validated against two independent experimental studies, and the results found to be in reasonable agreement.

As an alternative to bridges with rigid foundation systems, departments of transportation have begun implementing geosynthetic-reinforced soil (GRS) in an integrated bridge system (IBS) in bridge abutments over the last 20 years. GRS systems are used because they show some advantages over more conventional bridge designs. These advantages include low cost, short building time, and reduction of the relative settlement between bridge deck and approach embankments. GRS-IBS systems deal with the "bump at the end of the bridge" problem by allowing both the bridge deck and approaching road to settle or deform at the same rate, instead of resisting it. This paper focuses on documenting the performance of a GRS-IBS system, by studying a short-span bridge located on State Highway 40, southwest of Bloomer, Wisconsin. This bridge was built during the summer of 2012 and is being monitored for two years to track deformations caused by service and environmental loads. The monitoring campaign consists of surveying the foundation, abutment walls, bridge deck, approaching roads, and creek erosion. Preliminary results show that the GRS-IBS system has performed as expected, showing no differential settlement, thus solving the "bump at the end of the bridge" problem with a simple, cost-effective solution.

A newly developed mechanically stabilized earth (MSE) system consisting of large precast block with a mechanical connection using narrow geosynthetic reinforcement provided a cost-effective solution to a challenging project. Canadian National (CN) Railway needed to switch an at-grade rail crossing with a commuter system to an elevated crossing. Due to the overhead catenary electrical wire system of the commuter rail line, a metallic-reinforced MSE wall system could not be used. Geosynthetic-reinforced MSE wall systems are generally more cost effective than metallic-reinforced systems, and there is no concern using geosynthetic reinforcement near a catenary system. This unique project was one of the first to use this positive connection system with continuous reinforcement through the facing block. It was also the first geosythetic MSE wall system supporting dual railroad tracks with less than 1 degree face batter. The MSE system uses geogrid soil reinforcement in 300 mm (1 ft) wide strips. Because the reinforcement is in strips instead of full sheets, the MSE structure is designed with a reinforcement coverage ratio of 50% instead of 100%, which would be typical of full sheets. The MSE abutment is approximately 6.4 m (21 ft) tall at the bridge structure. The wall is being monitored by surveying to observe performance during and post construction. The wall sections were completed at the end of 2012. This paper will present the design, construction, and monitoring of this historic project.

This paper presents a preliminary calibration of region-specific resistance factors for two static capacity models for driven piles in Providence, Rhode Island. Current American Association of State Highway and Transportation Officials Load and Resistance Factor Design (AASHTO LRFD) bridge design specifications provide resistance factors for static capacity models commonly used in pile design. It is anticipated, however, that region- or site-specific resistance factor calibrations will lead to safer, more economical, and hence more sustainable pile designs. To perform the calibration, ultimate capacities were interpreted for 10 static loading tests performed on displacement piles driven to very dense glacial soils. Static capacity predictions were also made for the test piles using the Nordlund and SPT methods as outlined in the AASHTO bridge design specification. The first order second moment (FOSM) method was used to make preliminary estimates of the resistance factors for the two static capacity models using the bias data. New region-specific resistance factors of 0.20 and 0.42 were obtained for pile groups for the Nordlund and SPT methods, respectively. It is anticipated, however, that more economical pile designs could be achieved locally using the SPT method.

Integrity testing of drilled shafts and similarly constructed concrete foundations has evolved to combat the blind nature of the construction process and to increase quality assurance. The more popular methods include cross-hole sonic logging (CSL), gamma-gamma logging (GGL), and more recently thermal integrity profiling (TIP) and sonic caliper. Thermal integrity profiling, developed at the University of South Florida in the mid-1990s, utilizes the heat of hydration of curing concrete to evaluate the integrity of drilled shaft foundations. Comparing the results of the different test types is difficult due to the varied nature of the different tests. This paper looks at various shafts constructed across the nation, which were tested with thermal and at least one other method. When compared with CSL and GDL test results, TIP agreed with four of six cases for CSL and two of five cases for GDL. In the one case were both sonic caliper and inclination data were available, TIP showed good agreement.

This paper presents a case study of a deep soil-cement-bentonite (SCB) slurry trench cutoff wall constructed outside of Smithland, KY, in 2010. Installed to a maximum depth of 56 m, this cutoff wall is the deepest known seepage barrier installed using continuous trenching. The wall was installed around the perimeter of a deep excavation to reduce long-term dewatering costs associated with construction of a hydroelectric power plant adjacent to the Ohio River. After wall construction, a dewatering system was installed inside the area enclosed by the wall to facilitate the deep excavation. Preconstruction design and construction details are presented along with the results of a post-construction assessment of the hydraulic conductivity ( k ) of the wall. Steady-state groundwater flow measurements from the dewatering system coupled with information on the wall thickness and water levels inside and outside of the wall were used to obtain a large-scale estimate of the in situ k of the wall. The in situ k was compared with laboratory k values measured for specimens prepared from grab samples of the as-mixed SCB backfill. Comparisons also were made to the target (design) k and the expected field mixed backfill k established during a preconstruction bench-scale study. The comparisons revealed that the in situ k is approximately one order of magnitude less than the design k and approximately equal to the average laboratory k measured from grab samples and the expected k from the results of the bench-scale study.

Deep cement mixing (DCM) is usually used for in-situ ground treatment for weak soil. The highly variable strength within DCM columns, remains a problem in engineering practice. Precious studies of physical modeling on DCM, only used single-shaft. However, in real DCM, a multi-shaft system, usually with dual or four shafts, is adopted. This paper presents the development of a dual-shaft DCM apparatus for centrifuge model testing. Centrifuge model tests were conducted to study mixing uniformity of DCM columns and considerable test data was obtained. The test results regarding mixing uniformity of the dual-shaft system are compared with those by single-shaft system. Some findings on the advantages and limitations in using dual-shaft deep mixing system are pointed out and considerations for further improvement are proposed.

Evaluation of subgrade soil stiffness provides valuable information about the expected behavior and response of pavements, which can be used to group pavement sections with similar structural capacities and pavement maintenance and rehabilitation to prioritize projects. A deflection test, such as the falling weight deflectometer (FWD), is commonly used to determine subgrade resilient modulus (MR) from its measured deflection data. A correction factor has been applied to the American Association of State Highway and Transportation Officials (AASHTO) MR equation for adjusting the difference between laboratory MR and the in situ measurements (with the FWD). However, large variations on the correction factor result in less accuracy of subgrade MR based on FWD measurements. The objective of this research is to evaluate the accuracy of the AASHTO MR equation and improve its accuracy by adjusting the MR correction factor. This paper consists of subtasks: (a) evaluating the current AASHTO MR correction factor; (b) evaluating the affecting factors (i.e., subgrade soil stiffness, bedrock depth, highway classification, and environmental condition); and (c) developing a framework to determine accurate MR correction factor.

An innovative alternative to conventional bridge support technology, the Federal Highway Administration's (FHWA) geosynthetic-reinforced soil-integrated bridge system (GRS-IBS) utilizes closely spaced layers of geosynthetic reinforcement and compacted granular fill material to provide direct bearing support for structural bridge members. This new technology has a number of unique advantages, including reduced construction time and cost, generally fewer construction difficulties, and easier maintenance over the life cycle of the structure. This technology can also perform well under a variety of static and dynamic loading conditions if designed and constructed properly. These advantages have led to a significant increase in the rate of construction of GRS-IBS structures in recent years. This paper provides details about the implementation of a GRS-IBS project in Delaware, the first project of this type in the state. An overview of the design and construction process for this project is provided, along with a brief description of a custom-designed instrumentation system for monitoring the long-term performance of the GRS-IBS.

A series of density-based and modulus-based quality control tests were performed to evaluate and compare the performance of a number of in situ testing methods for control of soil compaction. This paper highlights the results from the study that focus on three in situ testing tools for compaction control: the lightweight deflectometer (LWD), the dynamic cone penetrometer (DCP), and the nuclear density gauge (NDG). In situ tests conducted using these tools were performed during construction of an embankment built with a coarse-grained soil in a series of lifts. Comparison of the in situ test results shows that that there is a notable variability in measured soil properties for each of the testing methods that were performed. All three in situ tests showed an increasing trend in the measured properties from pass-to-pass of the compactor, which indicates the suitability of these tests for proper control of the compaction process. However, the soil moduli measured by the LWD and DCP correlated poorly to the NDG dry unit weights. This lack of agreement was likely caused by a variety of factors, including variations in the tested soil volume between these devices and variations in the local moisture content and matric suction conditions. The effect of soil moisture content was shown to be particularly significant when interpreting the results of LWD and DCP tests, and the usefulness of multivariate regression analyses was explored for including this effect.

The direct simple shear test was developed as an element test in which, in principle, a uniform simple shear strain field was applied to a sample. In the intervening years a number of shortcomings have been identified with this testing apparatus, most notably the exact stress conditions within the sample are not known. However the test itself is not overly complex, and it is thought to better represent true in situ conditions when compared with the triaxial test. In particular, it allows for smooth rotation of the principal stress orientation, which is common in many practical geotechnical conditions. Consequently, simple shear testing remains a popular method to advance understanding of soil response. This paper documents a fundamental study of the direct simple shear apparatus using the discrete element method (DEM). A series of stacked cylindrical walls were used to simulate a laminar-type simple shear cell. The prototype simulations presented showed localized stress differences for the loose and dense samples. The DEM data also allows for direct determination of the strength parameters, stress path, and the angle of noncoaxiality. All simulations exhibited noncoaxial behavior. The loose sample showed less principal stress axis rotation and the principal axes' orientations became coincident at lower shear strains. © 2014 American Society of Civil Engineers.

This paper presents a case study of the use of underground injection control (UIC) wells to infiltrate stormwater beneath relatively impermeable near-surface soils at an elementary school. Stormwater had previously been routed to a central pipe and discharged to a ravine on an adjacent property, causing severe erosion. UIC wells were used to infiltrate stormwater into the subsurface beneath impermeable shallow soils to prevent such erosion and to comply with current stormwater regulations. The UIC well system consists of more than 50 UIC wells, each of which is 1 meter in diameter and 18 to 24 meters deep. Water-quality treatment is provided by catch basin dead storage and filters. Short-term pilot infiltration tests and three-dimensional numerical modeling of variably saturated flow were used to develop design infiltration rates and radii of influence for UIC wells. Infiltration testing on completed UIC wells helped address variable geological conditions during construction. The success of this sustainable stormwater drainage system was a result of favorable geological conditions, comprehensive design studies, a thorough site investigation, pilot testing, numerical modeling, and field verification testing during construction. UIC wells can work well at sites with limited space and a thick unsaturated zone.

Mechanically Stabilized Earth (MSE) retaining walls have been designed and constructed for over 40 years and their popularity has steadily grown due to low cost, ease of construction, and excellent performance record. Observations from post-earthquake reconnaissance efforts have also indicated that these retaining wall systems exhibit good performance under seismic loading, often exceeding the performance of conventional rigid and semi-rigid retaining wall systems. However, significant questions remain with regard to seismic design procedures for MSE walls, due in part to lack of sufficient test data for dynamic loading conditions. Data from centrifuge and 1-g shake table tests on small- to moderate-size specimens have been limited by scaling effects and use of non- standard materials and methods. The objective of this paper is to describe an ongoing research program at UCSD to conduct dynamic tests of full-scale (up to 7 m tall) MSE retaining walls using an outdoor shake table. The resulting data will provide important new information for the development of design standards for seismic regions and assessment of numerical models used to analyze the dynamic response of MSE walls.

The modified disconnected spread footing (MDSF) system is an innovative foundation concept that was used for support of the northern approach structure (Segment 4) at the Golden Ears Bridge crossing of the Fraser River in British Columbia, Canada. This foundation system consists of conventional rectangular spread footings supported by groups of lightly reinforced, 36 m long precast concrete piles. Unlike traditional piled foundations, the piles in the MDSF are separated from the spread footing by a lean concrete layer and a thin gravel layer. The driven piles are used to transfer axial compressive loads. Other structural demands (i.e., shear, moment, and uplift loads) are transferred to the soils through the spread footing and a group of short drilled shafts, which are rigidly connected to the spread footing. This paper describes the modeling techniques used in the three-dimensional (3-D) computer model developed to simulate the unique load-transfer mechanism occurring in the MDSF system under gravity and seismic loading. The 3-D model was developed using the computer program FB-MultiPier, which couples nonlinear finite element analysis for superstructure with nonlinear spring models for soils. Calibration of the 3-D model was conducted through a series of runs in which the contribution of each footing element (i.e., spread footing, piles, and shafts) were separately evaluated. It was demonstrated that the computer model is capable of handling the complex load-transfer mechanism in the MDSF system.

This paper presents findings from a case study conducted on a low-volume road bridge in Iowa, where geosynthetic-reinforced soil (GRS) was used as fill material in the reconstructed bridge abutments. The original steel bridge supported was on concrete abutments and was replaced with a longer railroad flat car bridge and spread footings founded on the GRS fill. The concrete abutments along with some of the existing fill were left in place to serve as GRS facing, and the soil under the new footing was excavated and replaced with GRS fill. The cost of constructing the bridge was about 60% lower than a conventional concrete bridge deck and abutments. Laboratory tests showed that samples reinforced with geosynthetic layers exhibit higher shear strength and lower permanent strain. When a static load was applied over the foundation with a loaded truck, horizontal stress increase was low along the excavation walls. Analysis indicated that the location of the water table and loading conditions influence the bearing capacity and global stability of the abutment system.

Air sparging is a technique that uses the injection of a gas (e.g., air, oxygen) into the subsurface to remediate saturated soils and groundwater contaminated with volatile organic compounds (VOCs). During air sparging, air or oxygen is injected into the subsurface below the lowest known depth of chemical contamination. The injected air will rise through the contaminated zones by buoyancy. Contaminant removal efficiency and air sparging performance are highly dependent on the pattern and type of airflow. Airflow, however, suffers from air channel formation (i.e., preferential paths for airflow), limiting remediation to smaller contaminated zones. This paper presents the results of experimental work investigating the possibility of controlling and improving airflow patterns through a saturated glass-bead medium using electromagnetic (EM) waves to enhance air sparging. The test setup consists of a resonant cavity made of an acrylic tank covered with transparent, electrically conductive films. Experimental measurement of the electric field component of EM waves is performed at different frequencies. Airflow pattern is also studied at different air-injection pressure levels with/without EM stimulation. The zone of influence (ZOI) during air sparging is monitored using digital imaging. A quantitative approach is then taken to correlate the characteristics of EM waves and airflow patterns.

The accurate calculation of wind uplift forces on an exposed geomembrane is essential for generating design requirements for the anchorage system. These requirements often largely dictate construction costs, so inaccuracies in the uplift calculation may have significant economic repercussions. Inaccuracies may occur when using generic suction factors rather than a site-specific assessment using computational fluid dynamics (CFD) technology. This paper presents preliminary research conducted to determine whether potential cost savings warrant more complex CFD modeling. Preliminary results comparing a two-dimensional case of an exposed geomembrane (which was used to develop generic suction factors commonly used to evaluate wind uplift) indicate the wind uplift forces calculated from a CFD model resulted in tensions that were significantly less than those using generic suction factors. Preliminary research was performed with the intention of employing CFD modeling to refine the simple prescription of generic suction factors on a site-specific basis.

Finite element programs allow for an enhancement in the computational capabilities of earthquake site response models. However, many finite element programs involve complicated constitutive models that are difficult for the end user to implement. We present a methodology for modeling earthquake site response within a general finite element framework, using an overlay model to represent nonlinear soil behavior. Using parallel load-carrying elements with varying stiffness and yield stress, the behavior of any given backbone stress-strain relation can be replicated, along with hysteretic unloading-reloading (Masing) behavior. Our finite element modeling methodology makes use of existing conventional elastoplastic material models available in any general finite element program, without requiring the specification of any complicated constitutive models. To represent overlay elements in a finite element model, the user defines a number of finite elements and assigns each of them identical node numbers. The only necessary input parameters are density, elastic constants, and the backbone curve of a stress-strain relation. This paper focuses on the application of one-dimensional total-stress site response, but the framework could be easily extended to model cyclic hardening and softening, three- dimensional wave propagation, and soil-structure interaction.

An integrated approach was used to remediate the Cortland-Homer former Manufactured Gas Plant in Homer, New York. The record of decision (ROD) for the former plant area required excavation of impacted soils to depths of nearly 14 m. In contrast, the ROD for the area downgradient of the former plant called for in situ solidification (ISS). The former plant area and the downgradient area are separated by U.S. Route 11, and impacted soils under the roadway were judged inaccessible. New York State Electric & Gas (NYSEG) and AECOM jointly proposed an alternative, integrated remedy, using auger-mix ISS treatment in both areas. This alternative facilitated installation of vertical barrier walls to contain impacted soils under the highway, enhancing the remedy's overall effectiveness. It also resulted in substantial cost savings. This paper summarizes the remediation design and construction. It discusses the use of rotosonic drilling to characterize coarse-grained glacial outwash soils, with focus on determining the size and frequency of cobbles and boulders. Furthermore, it reviews laboratory bench studies that were used to develop preliminary ISS mix designs and subsequent field trials to optimize the ISS grout mix. Construction is also discussed, including lessons learned.

When the performance function (or limit state) is a numerical model without an explicit form, reliability analysis based on this limit state is often difficult to perform. In this paper, a series of moment methods that is built on the solutions obtained from Plaxis T M , a commercially available finite element code, is adopted for probabilistic evaluation of serviceability failure in a braced excavation. The accuracy of the computed reliability index and probability of failure tends to increase when the higher-order moments are considered. In addition, the effect of spatial variability of soil parameters on the computed probability of serviceability failure is investigated. A well documented case history of a braced excavation in clay is analyzed, and the results show that the moment methods are effective and easy to apply for computing failure probability.

Poor soils conditions at a new tank farm site in Panama led to the use of ground improvement for settlement control and mitigation of seismic effects. The ground improvement consisted of stone columns in the upper 17 m, which were layered strata of loose silty fine sands and silts and preloading with wick drains to improve a layer of soft to medium stiff organic clayey silt from 17 to 26 m. The preloading was monitored with settlement plates, piezometers, and inclinometers at one tank, and the tank hydrotests were monitored with precision level surveys. The settlements during the preloading ranged from 1.5 to 2.2 m, which were about twice the estimated values based on high-quality lab tests. This paper discusses the overall performance of the ground improvement, the use of Asaoka and hyperbolic methods to evaluate the preload, and the correlations of soils properties from lab tests with back-calculated values from the field data and modeling efforts with PLAXIS.

This paper documents inter-analyst uncertainty/variability in dispersion and shear wave velocity (Vs) estimates from a blind-analysis study performed on a common experimental dataset of surface wave measurements. The dataset consists of both active-source and ambient-wavefield data collected using a variety of linear and circular arrays of surface receivers. Analysts were allowed to process as much of the data as desired and requested to report their dispersion and Vs results in a blind manner. This information was used to calculate inter-analyst frequency-dependent uncertainty in dispersion estimates and depth-dependent uncertainty in Vs. The focus of this study is not about evaluating how many/which analysts obtain the “correct” answer, but rather on quantifying the range of answers one might expect from different analysts attempting to characterize the same site.

The State Highway 161 (SH 161) President George Bush Turnpike Western Extension in Dallas, Texas, is a design-build project for the North Texas Tollway Authority (NTTA). The project includes the construction of a 6.5 mile long highway to handle increased traffic in the region. The project includes multiple drilled shaft supported bridges, retaining walls, and design of pavement systems. The subsurface deposits/geologic formations from south to north along the highway alignment include alluvium Fluviatie terrace deposits, the Eagle Ford formation, and the Woodbine formation. Alluvium and Fluviatie terrace deposits consist of gravel, sand, silt, and clay. Eagle Ford formation consists of high-plasticity clays near ground surface. With increasing depth, the high-plasticity clays change into shale. Woodbine formation generally consists of interbedded sands, cemented sands, and mudstones. Characterization of soils and optimization of geotechnical parameters for an economic design was a challenge for this project. Proper evaluation of soil parameters along the highway alignment was performed to design the foundation for various bridges, retaining walls, and pavements. This paper describes the field and laboratory-testing methodologies that were implemented to evaluate and characterize the subgrade of the pavement section along the project alignment.

Combined wave and surge overtopping caused earthen levee damage on the levee crest and land-side slope during Hurricane Katrina. The high turbulence of the overtopping flow may cause severe soil erosion during combined overtopping. High-performance turf reinforcement mat (HPTRM) is one of the most advanced flexible armoring technologies available today for severe erosion challenges. This study was to study turbulence and erosion characteristics of earthen levee strengthened by HPTRM system in the levee crest and land-side slope. A three-dimensional hydrodynamic and sediment transport model, ECOMSED, has been calibrated and verified with overflow discharge and full-scale overtopping experimental results. The full-scale laboratory study on combined wave and surge overtopping of a levee strengthened with HPTRM was conducted in a two-dimensional laboratory wave/flow flume. This paper describes the calibrated 3D model in the study of overtopping hydrodynamic flow, turbulent shear stress, turbulent kinetic energy, and erosion rate at the toe of land-side slope under combined overtopping condition. New equations for estimating turbulent shear stress, turbulent kinetic energy, and erosion rate at the toe of land-side slope were developed.

This paper reports a reduced-scale shake table test investigating the seismic response of a slurry wall. Soil-cement-bentonite (SCB), a common type of slurry wall, was evaluated in this research. A section of a slurry wall of 1.68 m long, 0.20 m wide, and 1.60 m tall was constructed and tested on a one-dimensional shake table. A 1.50 m × 1.87 m × 1.80 m box was anchored on the shake table and contained the slurry wall and the sandy soil that was compacted on both sides of the wall. The slurry wall and the confining soil were instrumented with accelerometers, linear variable differential transformers (LVDT), linear potentiometers, and dynamic soil stress gauges to respectively record the accelerations, vertical and horizontal deformations of the wall, and transient dynamic soil pressures on the wall during the simulated seismic excitations. Scaled 1989 Loma Prieta earthquake motions were simulated by the shake table. The testing was an improvement over previous testing by the authors and implemented flexible boundaries and dynamic scaling laws. The shake table tests provided a preliminary understanding of the seismic performances of the SCB slurry wall in levees and earth dams.

Thermal integrity profiling (TIP) is an increasingly popular form of post-construction quality assurance for drilled shafts. Therein anomalies in a shaft are indicated by variations in its thermal profile. As with any test method, the quality of the results depends largely on the level of analysis and the way in which test data is interpreted. With thermal integrity profiling, data interpretation techniques can fall into two schools of thought: (1) use of construction logs and concrete yield plots as a means to calibrate thermal data to shaft dimensions or (2) use of temperature prediction software to compare measured to model predicted thermal profiles. In theory, a signal matching approach using modeled shafts could reveal the shaft geometry that would produce the measured thermal profiles. However, the accuracy of models is largely dependent on input parameters such as shaft dimensions, boundary conditions, and concrete hydration behavior. Although the margins of error associated with these parameters can easily accumulate, useful trends and relationships about the temperature distributions within drilled shafts and surrounding environments can be identified. This paper examines computer generated trends and demonstrates ways in which they can be merged with existing TIP analysis techniques to produce a heightened level of data interpretation.