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The stability of slopes is typically evaluated by two-dimensional plane strain analysis. However, many slopes exhibit three-dimensional (3D) geometries, including slope corners. Several researchers have studied the stability of slope corners but found that the factor of safety (FS) was close to the FS for the plane strain case. The results of a new series of 3D finite element method (FEM) simulating slope corners, including slope angle, plan view angle, radius of curvature, and slope height are presented. They confirm that the FS does not vary much for corners compared to the plane strain case. However, 220 cases using an elastic-perfectly plastic soil model together with the FEM shear strength reduction method show that the displacement field is very different at the corners compared to plane strain with differences reaching over 100%. The displacement ratio between corners and plane strain is presented as a function of the plan view angle of the corner. Often failure is defined at a chosen large displacement, as in the ultimate load of foundation elements. If this concept is carried over to slope stability, it would indicate that the FS of corners should be very different from the plane strain case. A possible explanation is discussed. [ABSTRACT FROM AUTHOR]

In mining, open pits have slopes cut as steep as possible to ensure efficient mining yet not too steep to jeopardize safety. Building on existing contributions, the Texas A&M University Mine Slope database (TAMU-MineSlope) was created to provide global-scale insights into the runout mechanics of open pit slope failures and offer the database to engineers for further study. The database includes 134 cases of open pit slope failures that occurred at 76 mines worldwide. Based on energy principles and an analysis of the TAMU-MineSlope data, an equation to predict the travel distance of the slope failure mass is presented in this paper. Furthermore, based on the case histories analysis, an equation to predict the setback distance is proposed. Finally, the TAMU-MineSlope database shows that the average width to height ratio of the failing slope mass is 2.7 and that, for this ratio, the 3D factor of safety (FS) can reach a value 15% higher than the 2D FS. The database has been released in the public domain. [ABSTRACT FROM AUTHOR]

This paper presents the results of research on soil erosion and its mitigation by different methods such as grass, riprap, lime, and enzymes. The goal was to evaluate these methods for their degree of efficacy using laboratory erosion testing. The paper begins with a review of existing knowledge on erosion mitigation methods. The erosion resistance of natural and improved soil was investigated in the erosion function apparatus (EFA), a laboratory device for measuring erosion resistance in the velocity range of 0.3 to 6.5 m/s. EFA testing was performed on grass-covered soils, riprap-covered soils, enzyme-treated soils, and lime-treated soils. The erodibility of the soils before and after treatment was compared. The results of the EFA tests were also compared with a few large-scale field tests available in the published literature. The advantages, limitations, and range of applications of each erosion mitigation method are provided. [ABSTRACT FROM AUTHOR]

Soil erosion is a major problem in civil engineering. It is involved in bridge scour, meander migration, levee overtopping, internal erosion of earth dams, surface erosion of embankments, and cliff erosion. The best way to predict the erodibility of a soil is to measure it directly on a site-specific basis by in situ testing in the field or by testing samples in the laboratory. The borehole erosion test (BET) is a new in situ soil-erosion test proposed to measure the erosion of the walls of a borehole while wet rotary drilling takes place. The increase in diameter of the borehole is measured with borehole calipers as a function of time and for a given flow velocity. The result is a profile of soil erodibility as a function of depth. Tests in clay and in sand conducted at the National Geotechnical Experimentation Sites at Texas A&M University are presented and compared with laboratory soil-erodibility tests with the erosion function apparatus (EFA) on samples taken from the same borehole. Computational fluid dynamics (CFD) numerical simulations of the velocity and shear stress field for the BET are also presented. The experimental and numerical results show the lessons learned and lead to an evaluation of the advantages and drawbacks of this new test. [ABSTRACT FROM AUTHOR]

River meanders migrate over time and the consequences of this migration can create a problem for bridges and embankments near the river. This is why it is important to predict the lateral extent of future migration over the life of neighboring infrastructure. In the observation method for meander migration (OMM), the past movement and velocity history of the meander are used to back-calculate site specific erosion parameters. Those parameters serve as input to predict the meander migration for a chosen future velocity hydrograph. In this article and after a review of existing knowledge, the analytical steps leading to the development of the OMM are described, then the field and laboratory work at four full-scale meander migration case histories are presented, and then the four full-scale meander migration case histories are used to evaluate the OMM. The OMM has been automated in an Excel spreadsheet. [ABSTRACT FROM AUTHOR]

Groups of in-line piles connected by beams are being used to contain errant vehicles for roadside safety and perimeter protection of sensitive infrastructure. The effectiveness of in-line groups of piles to safely redirect or stop approaching vehicles has not been well investigated from the geotechnical point of view. In this paper, the performance of barriers is examined through full-scale crash tests and numerical simulations. The full-scale crash tests consisted of two different configurations of piles and beams as well as two different soil types: one was in loose sand and the other in hard clay. Both barriers were subjected to vehicle impact: one by a medium-duty truck and the other by a pickup truck. The barriers successfully contained the impacting vehicles. Detailed finite-element models of the barriers and the soil were developed and combined with the vehicle models to simulate the dynamic events. Comparison between predicted and measured behavior was used to calibrate the models. Additional simulations were performed to evaluate the effect of major structural and geotechnical design parameters including soil strength, pile spacing, and number of piles on the impact response of these systems. Practical recommendations are drawn from the experimental and numerical work. [ABSTRACT FROM AUTHOR]

Stiffened slabs-on-grade are one of the most efficient and inexpensive foundation solutions for lightweight structures on shrinkswell soils. The Ellison Office Building (EOB) is a 1-story steel-framed building founded on a clay formation of high shrink-swell potential. The foundation system of the EOB is composed of a rectangular stiffened slab-on-grade with approximate dimensions of 18.3 by 38.1 m. The slab thickness is 0.1 m, and the depth of all stiffening beams is 1.05 m. Beam spacing distances, center to center, are 3.05 and 3.81 m in the short and long directions, respectively. Exploration of subsurface soil conditions at the EOB site took place to determine soil index properties as well as unsaturated moisture diffusion and volume change characteristics for unsaturated soils. Monitoring the movements of both the slab-on-grade and the 4.5 m soil underneath continued for 2 years after foundation construction, since September 2004. Investigating the EOB foundation performance in light of the soil-structure interaction characteristics of the foundation showed two main distinct slab movement patterns: continuous global heave and localized fluctuating slab edge heave and drop movements. [ABSTRACT FROM AUTHOR]

Stiffened slabs-on-grade are one of the most economical solutions for 1- to 3-story buildings on shrink-swell soils. They consist, for example, of 1-m-deep, 0.3-m-wide beams resting on the soil, spaced 4 m apart in both directions covered by a 0.1-m-thick slab-on-grade. The challenge is to optimize the beamdepth, width, and spacing for the slab to be stiff enough that themovement of the soil at the edges of the slab will not cause undue bending of the foundation and the structure above it. Indeed, shrink-swell soils are affected by the weather and/or by the irrigation at the edges of the foundation and will swell and shrink as a result. This article presents a new method to design stiffened slabs on grade such that the differential movement divided by the length over which this movement takes place is within tolerable limits. The method gives the beam depth necessary to achieve such stiffness as well as the bending moment and shear force to be resisted. The method is automated in a spreadsheet called TAMU-SLAB. [ABSTRACT FROM AUTHOR]

A component of geotechnical applications involving nonisothermal conditions is the determination of the thermal properties of the ground. This paper presents a new test, called the thermal cone dissipation test (TCT), which overcomes most of the drawbacks observed in current in-situ techniques used to determine the thermal properties of soils. The equipment consists of a cone penetrometer equipped with thermocouples located behind the cone point. The TCT is pushed in the ground at the standard penetration rate of 2 cm/s, and the friction between the cone and the soil increases the cone temperature. The temperature decay is recorded as a function of time (for approximately 30 min) and this information is used to estimate the thermal conductivity and other thermal properties of soils. The calibration of the curves proposed in this work to estimate the thermal properties of the ground was based on three main activities: (1) in-situ experiments, carried out at three different locations involving different soil types; (2) laboratory investigation, aimed at obtaining the thermal conductivity of the soils studied in the field; and (3) numerical simulations, used to validate the proposed numerical models against the experimental data and to populate the proposed calibration curves including ground conditions to explore in the field. Very good agreements between field, laboratory and numerical results were obtained for the 11 TCTs studied in this research. It is expected that the proposed calibration curves will be enhanced in the future as additional experimental data become available. [ABSTRACT FROM AUTHOR]

Shrink-swell soils can cause distresses in buildings, and every year, the economic loss associated with this problem is huge. This paper presents a comprehensive system for simulating the soil-foundation-building system and its response to daily weather conditions. Weather data include rainfall, solar radiation, air temperature, relative humidity, and wind speed, all of which are readily available from a local weather station or the Internet. These data are used to determine simulation flux boundary conditions. Different methods are proposed to simulate different boundary conditions: bare soil, trees, and vegetation. A coupled hydro-mechanical stress analysis is used to simulate the volume change of shrink-swell soils due to both mechanical stress and water content variations. Coupled hydro-mechanical stress-jointed elements are used to simulate the interaction between the soil and the slab, and general shell elements are used to simulate structural behavior. All the models are combined into one finite element program to predict the entire system's behavior. This paper first described the theory for the simulations. A site in Arlington, Texas, is then selected to demonstrate the application of the proposed system. Simulation results are shown, and a comparison between measured and predicted movements for four footings in Arlington, Texas, over a 2-year period is presented. Finally, a three-dimensional simulation is made for a virtual residential building on shrink-swell soils to identify the influence of various factors. Copyright © 2015 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Scour is the removal of soil around bridge supports due to water flow during floods. One of the major problems with scour is in the case of unknown bridge foundations. Bridges with unknown foundations are listed in the National Bridge Inventory as having insufficient data for scour evaluation, particularly regarding foundation depth. Knowing the foundation depth is a critical component of scour risk assessment. Multiple nondestructive testing methods are currently used to determine the depth of unknown bridge foundations; however, many methods are hindered by the type of substructure. An advantage of using near-surface geophysical methods, specifically electrical resistivity (ER) and induced polarization (IP) imaging, is that the inversion processes yield subsurface images, thereby allowing the depth and, to a lesser extent, the foundation type to be seen. Unlike a majority of existing testing methods, ER and IP imaging do not physically use the structure so they are applicable to simple and complex foundation structures. In this paper, results of ER and IP imaging tests performed at the Texas A&M University National Geotechnical Experimentation Site, on a bridge with known foundation depth and a bridge with unknown foundation depth are presented. The applicability of ER and IP imaging to determine substructure characteristics for unknown bridge foundations is also discussed. A probability of nonexceedance estimate for predictions using IP is given to quantify IP imaging reliability. [ABSTRACT FROM AUTHOR]

Scour of the soil by flowing water around bridge supports is the number one reason for bridge collapse. Predicting the depth of the scour hole is an integral part of bridge foundation design, as it impacts the depth of the piles. Indeed, the scour depth must be ignored in the vertical and horizontal resistance of the piles. This paper presents a method to predict the progression of the scour depth around bridge supports as a function of time when subjected to a velocity hydrograph. It also addresses the issue of layered soils. The equations make use of the commonly used water velocity and dimensions of the obstacle, but add a new and important component: the soil erosion function to characterize the degree of soil resistance to erosion. The equations apply to pier scour, contraction scour, and abutment scour. The predicted output is the scour depth as a function of time for a given velocity hydrograph and soil layer stratigraphy. A comparison between measured and predicted scour depth is presented, but more comparisons are necessary, particularly at full scale. [ABSTRACT FROM AUTHOR]

Scour of the soil by flowing water around bridge supports is the number one reason for bridge collapse. Predicting the depth of the scour hole is an integral part of the bridge foundation design, as it impacts the depth of the piles. Indeed, the scour depth must be ignored in the vertical and horizontal resistance of the piles. This paper presents a method to calculate the maximum depth of the scour hole around bridge supports when subjected to a constant water velocity. Most existing methods take into account the water velocity and the geometry of the obstacle but not the soil type. The method presented in this paper keeps those important variables and adds the paramount influence of the soil erosion characteristics. It is developed on the basis of 94 flume tests, some of them very large laboratory-scale tests, as well as dimensional analysis and experience. It applies to pier scour, contraction scour, and abutment scour. The method is evaluated by comparing the maximum scour depth predictions against measured data from 10 databases of pier, contraction, and abutment scour depths. [ABSTRACT FROM AUTHOR]

Bridge scour is the loss of soil by erosion because of 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 owing to severe deformation. This paper addresses three topics related to bridge scour. First, a set of databases was used to quantify the statistical parameters associated with the scatter between the predicted and measured pier scour depth, as well as the probability that a deterministically predicted pier scour depth will be exceeded. These databases also were used to provide the bias factors in current predictions. Secondly, these statistical parameters were used to develop a reliability-based load and resistance factor design for shallow and deep foundations subjected to scour. The goal was to provide a design procedure where the reliability of the foundation is the same with or without scour. Reliability only addresses the probability of success and, therefore, of failure. Finally, the discussion was broadened by using the concept of risk defined as the probability of failure times the value of the consequences. In this third part, the risk associated with bridge scour was quantified and compared to risks associated with other engineering structures. Target values of acceptable risk were recommended as part of the conclusions. [ABSTRACT FROM AUTHOR]

Lane/shoulder drop-off or heave due to expansive soils beneath is a common distress in both concrete and asphalt pavements, resulting in substantial discomfort, safety hazard and vehicle damage. The situation becomes worse when exposed to moisture changes, particularly in Texas, Colorado, Arizona, California, etc. where many soils are expansive soils. Therefore, expansive soils pose great challenges for the design of pavements and foundations. One of the most difficult issues for designing pavements and foundations on expansive soils is to predict the volume change of the soils. In this study, current methods for movement predictions are summarised and their relationships and shortcomings are discussed. It is found that all these methods have the same theoretical basis. Based on the theory of unsaturated soil mechanics, it is found that the water content and the mechanical stress can be used to determine the soil status. Hence, a void ratio versus mechanical stress and water content surface is constructed, which coupled both mechanical stress and suction's influences on volume change of expansive soils. The new surface is developed into a coupled water content method that can be used to predict the potential vertical swell and the potential vertical shrink simultaneously, while all the existing methods can only predict the potential vertical rise. The method is used to analyse the data collected from a construction site at Arlington, Texas. The predicted movements match the measured data reasonably well. The method is simple and overcomes the shortcomings existing in the current movement prediction methods for expansive soils. [ABSTRACT FROM AUTHOR]

This lecture presents four case history examples of erosion processes. Because the topic of soil and rock erosion is relatively underdeveloped in geotechnical engineering, an introduction precedes the case histories to describe some fundamental aspects of erosion. Erosion involves the soil or rock through its erodibility, the water through its velocity, and the geometry of the obstacle through its size and shape. Knowledge of these three components is needed for any erosion problem to be studied and solved. A set of fundamental issues are addressed in the first part including an erodibility classification for soils and rocks, an explanation of the stresses imposed by the water on the soil-water or rock-water interface, and an explanation of how the geometry impacts the problem. The Woodrow Wilson Bridge case history outlines a new and less conservative method to compute the scour depth and gives examples of bridge scour calculations. The Brazos River meander case history outlines a new method to predict meander migration and gives an example of migration calculations. The Pointe du Hoc case history gives an explanation of a process of rock cliff erosion. The New Orleans levees case history gives an example of erosion of levees by overtopping and proposes an erosion design chart for levee overtopping. Whenever possible the results are presented in a probabilistic fashion. All case histories make use of the erosion function apparatus, an apparatus developed to quantify the erodibility of a soil or rock and to give the constitutive law for erosion problems: the erosion function. The power point slides for the lecture including many photos of the case histories are available at under “Lectures” and the video (DVD) of the lecture is available from the author, free of charge. [ABSTRACT FROM AUTHOR]

Constitutive surfaces are indispensable for investigation of the behavior of soils. Saturated and unsaturated soils coexist in most engineering problems and it is meaningful to develop constitutive surfaces covering both saturated and unsaturated conditions which help to investigate the behavior for both saturated and unsaturated soils in a unified way. At present, the methodologies used for saturated and unsaturated soils are different and few researchers consider the constitutive surfaces for saturated soils. For unsaturated soils, the suction-controlled triaxial tests are usually laborious, time consuming, costly, and may not justify routine engineering projects. This paper discusses the role of constitutive surfaces in soil mechanics and presents an improved approach over existing interpolation methods to construct the constitutive surfaces for saturated and unsaturated conditions for a stable-structured soil using simple laboratory tests. [ABSTRACT FROM AUTHOR]

The San Jacinto Monument was built in 1936 to commemorate the 100-year anniversary of the victory of the Texan army over the Mexican army. The victory at the battle of San Jacinto followed the defeat at the battle of the Alamo and secured the independence of Texas, as well as several other states along the Mexican border. The monument consists of a 176.5-m-high column resting on a large square mat with each side=37.8 m. The mat foundation was designed by Raymond Dawson who chose an average pressure of 223.8 kPa under the mat. Dawson had settlement points placed on the mat foundation together with benchmarks away from the monument. The settlement of the monument has been recorded over the last 70 years and shows a total settlement to date of 0.329 m. The settlement appears to be almost complete. This remarkable case history is used to evaluate current practice of calculating consolidation settlement and a best approach is suggested for such structures. Other issues addressed include the depth of influence, the time rate of settlement, the elastic-modulus approach, and the ultimate bearing capacity. [ABSTRACT FROM AUTHOR]

A study of the assumptions involved in the ultimate bearing capacity equation indicates the shortcomings of that equation and load test data confirm these shortcomings. A new approach using a normalized load settlement curve is proposed to alleviate these shortcomings and to obtain the complete load settlement curve for a footing in sand. The normalization consists of plotting the mean footing pressure divided by a measure of the soil strength within the depth of influence of the footing versus the settlement divided by the footing width. It is shown that the normalized load settlement curve for a footing is independent of footing size and embedment. It is proposed to obtain the normalized curve point-by-point from a soil test. Because the deformation of the soil observed under full-scale footings during loading indicates a barreling effect similar to the soil deformation around a pressuremeter probe, the preboring pressuremeter curve is used to obtain the footing curve. The new method consists of transforming the preboring pressuremeter curve point-by-point into the footing load settlement curve. Load tests and numerical simulations are used to propose a method for a rectangular footing near a slope subjected to an eccentric and inclined load. The new method gives the complete load settlement curve for the footing and alleviates the problems identified with the bearing capacity equation. [ABSTRACT FROM AUTHOR]

There is a trend toward using the modulus as an alternative to dry density in compaction control because of the undesirable nuclear source in the current field density gage and because a modulus is often used in the design of roadway bases and compacted fills. The Briaud compaction device (BCD) is a new instrument used to obtain a soil modulus in only a few seconds; it consists of leaning on a rod equipped with a thin circular metal plate at the bottom end and recording the bending of that plate under a standard load. This article describes the theory and the experiments that have been performed to validate the new instrument. This validation is based on a comparison to a simple plate test and on a numerical simulation of the BCD test. A recommended procedure is outlined in the conclusions. The BCD is used in the lab on top of the soil in the Proctor mold to obtain the lab modulus versus water content curve and select a target value. Then the BCD is used in the field to verify that the target modulus has been achieved. [ABSTRACT FROM AUTHOR]

A new method is proposed to estimate the vertical movement of the ground surface for soil that swells and shrinks due to variations in water content. The water content is used as the main soil parameter and a shrink test is suggested to obtain the relationship between the change in water content and the volumetric strain induced. We propose estimating the change in water content and the depth of seasonal moisture changes from local databases or from existing techniques. The method is evaluated by comparing the predicted movement and the measured movement of four full-scale spread footings over a period of 2 years. [ABSTRACT FROM AUTHOR]

Compares the depth of scour in sand and in clay and investigated the effects of the Reynolds number, Froude number and approach flow depth on scour depth. Experimental equipment and procedure; Discussion on hyperbolic extrapolation; Experimental results and data analysis; Conclusions.

Details a study which presented the results of a large scale project on full-scale VERT wall in sand. Site and soil properties; Modulus and strength; Conclusions.

Focuses on a study which examined the reliability of large-strain dynamic methods to predict the static capacity of bored piles. Schematic view of static load test; Rate effect and inertia effect in statnamic tests; Predictions of static capacity from drop weight tests.

Highlights a the study which investigated the behavior of five spread footings in sand. Description of the load tests; Information on the creep settlement; Differences between strain and depth.

Proposes the Scour Rate In COhesive Soils (SRICOS) method to predict the scour depth versus time around a cylindrical bridge pier of diameter founded in clay. Total number of bridges collapsed in the United States; Division of scour; Details on shear stress; Maximum depth of scour; Method improvements; Conclusions.

Utilizes a three-dimensional nonlinear finite-element analysis to study the influence of various design decisions for tieback walls. Literature on tieback walls; Study of boundary effect using a linear elastic soil; Description of soil and structure element model; Simulation of excavation sequence.

Presents the field measurements of low-pressure ground anchors at the National Geotechnical Experimentation Site at Texas A&M University. Constituents for the construction of grouted anchor; Significance of bond length on the average ultimate load for the anchors; Higher ultimate capacities of anchors with shorter tendon bond lengths.

Describes a set of recommended curves for a soil method and the P-y path method to simulate the construction sequence of excavation and tieback stressing. Reference deflections for plan strain P-y curves in clay; Comparison with pressure diagram methods; Measured and calculated responses for one-row anchor wall.

Focuses on developing design and construction guidelines for downdrag on uncoated and bitumen-coated piles. Bitumen selection process; Influence of temperature on viscosity; Hand calculation examples; Master curves for soft bearing pile lubricant.

Studies the behaviour of the soil-nailed walls constructed under a bridge abutment using a three-dimensional nonlinear finite-element analysis. Utilization of a modified hyperbolic soil model with unloading hysteresis; Calibration of the model against an instrumented case history; Variability of parameters to evaluate their influence on the design process.

Presents a simple approach for lateral load on piles (SALLOP) for the design of piles subjected to horizontal loads. Prediction of lateral pile capacity; Description of the non-linear behavior of the soil springs by the P-y curves; Zero-shear depth; Predicted versus measured lateral capacities; Prediction of deflection at working loads.

Presents a thermodynamic analysis of gas hydrates, a type of ice that burns when ignited. Conductor size nd latent heat influence; Pressure temperature equilibrium for hydrate and water; Temperature rise around a hot pipe buried in soil.

Discusses the Lateral Wave Activated Stiffness test that had been developed to obtain the lateral static stiffness of a pile. Use of considerable software development and a large number of large scale field test as requirements of the process; Requirements needed for field test.

The computational fluid dynamics (CFD) solver FANS3D [Finite-Analytic Navier-Stokes code for three-dimensional (3D) flow] is coupled with a sediment transport model to simulate scour hole backfilling under unidirectional flows (current-only). FANS3D solves 3D, unsteady, incompressible Navier-Stokes equations in nonstaggered, general curvilinear coordinate systems. For the present study, the k-ε model is used for turbulence closure. The overset grid technique is utilized to generate the computational domain consisting of multiple blocks with different structures. The coupled model is validated with both clear-water and live-bed scour experiments. The numerical solution is also verified to be consistent against changes in time step size and grid density. Backfilling is initiated by first obtaining the equilibrium scour under a "flood" and then reducing the approach velocity to a "normal" flow, both of which conditions are in a live-bed scour regime. Using this approach, backfilling is successfully simulated around a cylindrical pier with three different hydrographs (variable velocity). The backfilled scour hole is compared with the equilibrium scour hole formed under normal flow (constant velocity). This study found that a given unidirectional flow velocity results in the same equilibrium scour depth regardless of the initial bed morphology. The location of the maximum depth inside the scour hole is also found to be a characteristic of the flow velocity. [ABSTRACT FROM AUTHOR]

The rapid modernization has been mainly based on non-renewable fossil-fuels sources with the associated uncontrolled release of greenhouse gases impacting negatively on our environment. New renewal energy technologies, like shallow geothermal systems can help to solve this problem. This method harnesses constant and moderate ground temperature that is used to assist in the air conditioning of buildings. This technology is growing rapidly because it consumes less conventional energy for operation, which in turn results in fewer CO 2 emissions. A group of energy piles was installed and instrumented as part of the foundation system of a new five-story building constructed in Texas A&M University, USA. This setup is used in this research to explore the performance of this technique to control the building temperature under cooling-dominated weather conditions. This study found that integrating energy piles in building foundations could be an economical and environmentally friendly solution also under such climate conditions, but attention should be paid to the thermodynamic efficiency of the system when unbalanced pile-ground heat-transfer cycles take place through the year. ∙ Pilot energy-piles tests in a building operated under a cooling-dominated climate. ∙ Simulation of the long-term (30 years) performance of the energy pile system. ∙ Economic study anticipates a payback period of around 13 years. ∙ Prevailing cooling demand leads to unbalanced heat transfer cycles through the year. ∙ Progressive increase of ground temperature jeopardizes long-term system efficiency. [ABSTRACT FROM AUTHOR]

Summary: Railroad track problems have been exacerbated by the continuous increase in freight loads and train traffic. The need to implement soil improvement technique in a relatively short window‐time (ie, to minimize train‐traffic disruption) is a key aspect to be considered when adopting a convenient remedial solution to control settlements in railroads constructed on problematic subgrades. Rigid inclusions are selected in this paper because they are reliable solutions relatively easy to implement. Furthermore, they can be used in different ground conditions and are suitable for short construction times (eg, do not require a curing time, as in grouting methods). Typical (analytical) methods for the design of rigid inclusions are adopted in this paper to define an optimal distribution of piles for the case of existing railroads. The selected layout is then analyzed in detail by means of a 3‐D dynamic finite element simulator using both, elastoplastic and elastic models. The performance of rigid inclusions is studied considering different operational scenarios, with dynamic and static loads, as well as involving subgrades with different plasticity index values. It is found that the predictions from the analytical design methods for rigid inclusion tend to be unconservative when compared against the finite element results. As for the numerical solutions, the most unfavorable stress condition is associated with the dynamic elastoplastic finite element solution. It is estimated that the rigid inclusions will contribute to a reduction in the ground settlements of around 15% to 20%, depending on the subgrade plasticity index. [ABSTRACT FROM AUTHOR]

Presents comments on a study undertaken by researchers on closure to flume tests for scour in clay at circular piers. Accuracy of scour depth equation that correlates constant y[subs]/D to constant R with that of constant FD; Pier reynolds number values for different scour tests performed; Comparisons between scour depth versus time curve and exponential and hyperbolic model.

The main objective of this paper is to develop equations correlating the erosion resistance of a soil to its common geotechnical properties. A total of 975 erosion tests and approximately 13,600 associated common geotechnical properties were organized in a database called Texas A&M University (TAMU)-Erosion. About 300 of the 975 erosion tests and approximately 4,200 associated common geotechnical property tests were performed at Texas A&M University over the past 20 years. In parallel, an additional 675 erosion tests and approximately 9,400 corresponding common geotechnical properties were collected from the open literature. The erosion tests include mostly the erosion function apparatus test (EFA), jet erosion test (JET), and hole erosion test (HET). The raw data for all tests are embedded in TAMU-Erosion, along with an inquiry operation manual that allows the user to search the database. This database was used along with a standard statistical regression method and a probabilistic representation to develop the best equations correlating the erodibility parameters to the geotechnical properties. The best fit for each equation was quantified using standard goodness of fit indices. The best equations are presented along with probability curves conveying to the user the probability that the predicted value will be overpredicted or underpredicted. [ABSTRACT FROM AUTHOR]

Energy piles are bi-functional foundation elements used as structural support as well as ground heat exchangers for shallow geothermal energy systems. Because they are relatively short, energy piles may be partially embedded in unsaturated soils. Saturation conditions influence the thermal properties of the ground and therefore the heat exchange rate, which in turn affects the efficiency of energy piles. This paper combines analytical, experimental and numerical investigations to evaluate the heat exchange rate of energy piles partially or fully embedded in unsaturated soils. The proposed analytical solution is based on the cylindrical heat source theory that treats the soil as a semi-infinite, homogeneous, and isotropic medium. The solution from this theory is multiplied by a function developed analytically in this paper and the outcome is the heat exchange rate for energy piles in unsaturated soils. The proposed function depends on soil saturation, soil and pile thermal properties, and pile geometry. The analytical solution was compared against a finite element solution; which was in turn validated against results from laboratory experiments. Very satisfactory agreements between the analytical, numerical and experimental outputs were observed. The proposed method can be used for a quick and simple evaluation of the efficiency of energy piles in unsaturated conditions. The proposed analytical solution can also be a useful tool for the verification of numerical codes developed for the design of energy piles in unsaturated soils. [ABSTRACT FROM AUTHOR]

Energy piles make use of constant and moderate ground temperature for efficient thermal control of buildings. However, this use introduces new engineering challenges because the changes of temperature in the foundation pile and ground induce additional deformations and forces in the foundation element and coupled thermo-hydro-mechanical phenomena in the soil. Several published full-scale tests investigated this aspect of energy piles and showed thermally induced deformation and forces in the foundation element. In parallel, significant progress has been made in the understanding of thermal properties of soils and on the effect of cyclic thermal load on ground and foundation behavior. However, the effect of temperature on the creep rate of energy piles has received practically no attention in the past. This paper reports the experimental results of an in situ tension thermo-mechanical test on an energy pile performed in a very stiff high plasticity clay. During the in situ test, the pile was subjected to thermal loading by circulating hot water in fitted pipes, simulating a thermal load in a cooling-dominated climate, at different levels of mechanical loading. The axial strain and temperature in the pile, and the load-displacement of the pile were monitored during the tension test at different locations along the center of the pile and at the pile head, respectively. The data showed that as the temperature increases, the observed creep rate of the energy pile in this high plasticity clay also increases, which will lead to additional time-dependent displacement of the foundation over the life time of the structure. It was also found that the use of geothermal piles causes practically insignificant thermally induced deformation and loads in the pile itself. [ABSTRACT FROM AUTHOR]

Scour at a bridge pier is the formation of a hole around the pier due to the erosion of soil by flowing water; this hole in the soil reduces the carrying capacity of the foundation and the pier. Excessive scour can cause a bridge pier to fail without warning. Current predictions of the depth of the scour hole around a bridge pier are based on deterministic models. This paper considers two alternative deterministic models to predict scour depth. For each deterministic model, a corresponding probabilistic model is constructed using a Bayesian statistical approach and available field and experimental data. The developed probabilistic models account for the estimated bias in the deterministic models and for the model uncertainty. Parameters from both prediction models are compared to determine their accuracy. The developed probabilistic models are used to estimate the probability of exceedance of scour depth around bridge piers. The method is demonstrated on an example bridge pier. The paper addresses model uncertainties for given hydrologic variables. Hydrologic uncertainties have been presented in a separate paper. [ABSTRACT FROM AUTHOR]