Showing papers in "Geotechnique in 2005"
TL;DR: In this article, the authors examined the long-term performance of modern municipal solid waste (MSW) barrier systems and the latest techniques for predicting their performance, and indicated that the primary leachate collection systems may have service lives that range from less than a decade to more than a century, depending on the design details, waste characteristics and mode of operation.
Abstract: This lecture describes the latest findings with respect to the long-term performance of modern municipal solid waste (MSW) landfill barrier systems. Field data relating to the clogging of leachate collection systems and the latest techniques for predicting their performance are examined. It is indicated that the primary leachate collection systems may have service lives that range from less than a decade to more than a century, depending on the design details, waste characteristics and mode of operation. Recent data indicate that landfill liner temperatures can be expected to reach at least 30–40°C for normal landfill operations. With recirculation of leachate the liner temperature increases faster than under normal operating conditions, and may be expected to exceed 40°C. Temperatures (up to 40–60°C) may occur at the base of landfills where there is a significant leachate mound. Temperature is shown to have a significant impact on both contaminant migration and the service life of the liner system. Field...
510 citations
TL;DR: In this paper, a series of high frequency cyclic triaxial tests have been conducted to examine the effects of confining pressure and ballast degradation on railway substructures.
Abstract: Traditional railway foundations or substructures have become increasingly overloaded in recent years due to the introduction of faster and heavier trains. A lack of substructure re-engineering has resulted in maintenance cycles becoming more frequent and increasingly expensive. Two significant problems arising from increasing axle loads are differential track settlement and ballast degradation. One potential method of enhancing the substructure is by manipulating the level of ballast confinement. To investigate this possibility, a series of high frequency cyclic triaxial tests have been conducted to examine the effects of confining pressure and
307 citations
TL;DR: In this article, an experimental study was carried out to investigate the shear strength of a compacted non-active clay (Speswhite kaolin) and a shearbox was modified to allow the direct measurement of negative pore water pressure using Trento high-suction tensiometers.
Abstract: An experimental study was carried out to investigate the shear strength of a compacted non-active clay (Speswhite kaolin). A total of 33 statically compacted specimens were prepared, at vertical stresses of 300, 600 and 1200 kPa and water contents ranging from 0·24 to 0·34. This made it possible to explore a broad range of initial compaction-induced conditions and hence to examine whether differences in water retention characteristics and shear strength are due to differences in initial compaction-induced state or are to be attributed to fundamentally different microfabrics. A shearbox was modified to allow the direct measurement of negative pore water pressure using Trento high-suction tensiometers. Tests were carried out at constant water content by monitoring suction changes. In these tests, it was possible to investigate the transition from unsaturated to saturated states. In the first stage of the test, the specimen was compressed at constant water content. The specimen was therefore wetted, in the s...
206 citations
200 citations
TL;DR: In this article, a program of testing on suction caisson foundations in an artificially prepared sand test bed near Luce Bay, in Scotland, is described, with the results relevant to the design of either monopod or quadruped foundations for offshore wind turbines.
Abstract: A programme of testing on suction caisson foundations in an artificially prepared sand test bed near Luce Bay, in Scotland, is described The tests are relevant to the design of either monopod or quadruped foundations for offshore wind turbines Records are presented for suction installation of the caissons, cyclic moment loading under both quasi-static and dynamic conditions to simulate the behaviour of a monopod foundation, and cyclic vertical loading and pullout of caissons to simulate one footing in a quadruped foundation Variations of stiffness with loading level of the foundation are observed, with high initial stiffness followed by hysteretic behaviour at moderate loads and degradation of response at high loads Some implications for the design of wind turbine foundations are briefly discussed
181 citations
TL;DR: In this paper, an elastic continuum solution and a closed-form Winkler solution with Vesic subgrade modulus were compared for the problem of tunnelling effects on existing pipelines.
Abstract: An elastic continuum solution and a Winkler solution of the problem of tunnelling effects on existing pipelines are given. A comparison is made between an elastic continuum solution and a closed-form Winkler solution with Vesic subgrade modulus. Although applying the Vesic expression results in the same moments and displacements under external loading in a Winkler system and the elastic continuum, it is found that its use is not necessarily adequate for the problem of tunnelling effects on pipelines and may not be conservative owing to possible underestimation of bending moments. An alternative expression for the subgrade modulus is provided, resulting in similar maximum bending moments in the Winkler and elastic continuum systems.
165 citations
TL;DR: In this article, the authors derived elasticity models that allow for variation of elastic moduli as power functions of mean stress, while guaranteeing thermodynamic acceptability, and the important issue of the dependence of secant stiffness on strain amplitude (a phenomenon related to dissipation processes in the soil) is acknowledged.
Abstract: The elastic behaviour of granular materials is non-linear, in that the small-strain tangent stiffness depends on the stress level. The elastic moduli typically vary as power functions of the mean stress. Simple models of this nonlinearity can result in behaviour that violates the laws of thermodynamics. To guarantee that an elasticity model is thermodynamically acceptable it must be possible to derive the elastic behaviour from a free energy potential (or alternatively from a complementary energy potential). In this paper elasticity models are derived that allow for variation of elastic moduli as power functions of mean stress, while guaranteeing thermodynamic acceptability. The important issue of the dependence of secant stiffness on strain amplitude (a phenomenon related to dissipation processes in the soil) is acknowledged but not addressed here.
153 citations
TL;DR: In this paper, a method based on the concept of two-stage scaling is proposed that allows expanded use of the currently available facilities. But this method requires a large scaling factor λ = μη (prototype/physical model) which can be broken down into smaller scaling factors μ and η, and thus the centrifuge model tests can be performed with a smaller scaling factor.
Abstract: The trend toward physical modelling of larger prototypes triggers a move towards expansion of the current capability of dynamic centrifuge tests. In this paper a method based on the concept of two-stage scaling is proposed that allows expanded use of the currently available facilities. In the first stage a prototype is scaled down into an intermediate virtual model based on the scaling relations in a 1g field with a scaling factor of μ (prototype/virtual model). In the second stage this model is scaled down into a physical model using the conventional scaling relations in the centrifugal field with a scaling factor of η (virtual model/physical model). In this manner, a large scaling factor λ = μη (prototype/physical model) can be broken down into the smaller scaling factors μ and η, and thus the centrifuge model tests can be performed with the smaller scaling factor η. In effect, the limits in the scaling factor for the currently available centrifuge facilities can be expanded by a factor of μ. Validation...
150 citations
TL;DR: In this paper, a finite-scale weakly stationary random field model is used to characterize normalised cone tip resistance and friction ratio (FR) rigorously using a finite scale weakly-stationary random field.
Abstract: Random field modelling of soil variability allows significant statistical results to be inferred from field data; moreover, it provides a consistent framework for incorporating such variability in reliability-based design. Cone penetration testing (CPT) is increasingly appreciated because of its near-continuity and repeatability. Stress-normalised CPT parameters are included in widely used engineering procedures. Nonetheless, the results of variability analyses for these parameters are surprisingly limited. This paper attempts to characterise normalised cone tip resistance (qc1N) and friction ratio (FR) rigorously using a finite-scale weakly stationary random field model. It must be emphasised that inherent soil variability so determined strictly refers to the variability of the mechanical response of soils to cone penetration. The variability of soil response potentially depends on the failure mode (shear for sleeve friction or bearing for tip resistance) and most probably on the volume of soil influenced...
147 citations
TL;DR: In this paper, the authors used the Hasofer-Lind index and first-order reliability method (FORM) to evaluate the reliability of a retaining wall and proposed a spreadsheet-based probabilistic approach based on the work of Low & Tang.
Abstract: Geotechnical engineers have long used the lumped factor of safety approach in the design of foundations and retaining walls. A more recent alternative is the limit state approach using partial factors, for example as suggested in Eurocode 7. Yet another approach is perhaps more flexible and rational: design based on a target reliability index that reflects the uncertainty of the parameters and their correlation structure. Among the various versions of reliability indices, the Hasofer–Lind index and first-order reliability method (FORM) are more consistent. This paper illustrates practical reliability-based design procedures for retaining walls based on the Hasofer–Lind index and FORM. Correlated normal and non-normal random variables are considered. The efficient spreadsheet-based probabilistic approach, based on the work of Low & Tang, achieves the same result as the Hasofer–Lind method and FORM, but uses an intuitive expanding dispersion ellipsoid perspective that greatly simplifies the computations and...
143 citations
TL;DR: In this paper, a coupled hydromechanical model and a finite element based slope stability program are developed to study the behaviour and stability of deformable unsaturated soil slopes, and illustrate their application in probabilistic study by an example of a hypothetical unsaturated slope considering the variability of soil properties.
Abstract: Both hydraulic properties and shear strength properties of unsaturated soils can affect the stability of a soil slope during a rainstorm. The uncertainties of hydraulic property parameters for unsaturated soils and their effects on the reliability of slopes under rainfall condition have been studied recently (Chong et al., 2000; Tung & Chan, 2003). For example, Chong et al. (2000) studied the influences of the uncertainty of each parameter in the soil-water characteristic curve (SWCC) and the permeability function on the safety factor of unsaturated soil slopes using Monte Carlo simulations. Tung and Chan (2003) performed probabilistic analyses of rainfall infiltration and slope stability considering uncertainties in SWCCs by the Latin hypercube sampling technique. In both studies the deterministic model used is an uncoupled seepage analysis program Seep/W (Geo-slope Ltd, 2001a) and a companion slope stability analysis program Slope/W (Geo-slope Ltd, 2001b). Seep/W is formulated for conditions of constant net normal stress and non-deformable soil media. However, under real situations, the seepage and flow processes in a deformable soil are influenced by soil deformations. A coupled hydromechanical model is therefore preferred to analyse the behaviour and stability of a deformable soil slope subjected to rainfall. The objectives of this paper are to develop a coupled hydromechanical model and a finite element based slope stability program to study the behaviour and stability of deformable unsaturated soil slopes, and to illustrate their application in probabilistic study by an example of a hypothetical unsaturated soil slope considering the variability of soil properties. (A)
TL;DR: In this article, a critical evaluation of model factors for laterally loaded rigid drilled shafts (bored piles) is presented, and both the lateral or moment limit and hyperbolic capacity are considered to make explicit the dependence of model factor on the criterion for interpreting 'capacity' from load test data.
Abstract: This paper presents a critical evaluation of model factors for laterally loaded rigid drilled shafts (bored piles). Both the lateral or moment limit and hyperbolic capacity are considered to make explicit the dependence of model factors on the criterion for interpreting ‘capacity’ from load test data. Although the hyperbolic capacity may be closest to the theoretical ultimate state or upper bound, results indicate that it generally does not produce a mean model factor of 1. When the measured capacity is interpreted consistently from load test data, the coefficient of variation (COV) appears to remain relatively constant between 30% and 40%. The range of the mean bias for the lateral or moment limit is 0·67 to 1·49, whereas that of the hyperbolic capacity is 0·98 to 2·28. Based on available data, a log-normal probability model appears adequate for reliability analysis. Laboratory-scale load tests conducted in uniform soil deposits prepared under controlled laboratory conditions are ideal for establishing b...
TL;DR: In this paper, a half-spudcan model was used to visualise the soil flow mechanisms around the spudcan during penetration, and the formation of a cavity was revealed by both centrifuge model tests and finite element analysis.
Abstract: Centrifuge model tests and finite element (FE) analysis have been conducted to study the penetration of spudcan foundations in uniform clay with nominally constant strength with depth. In particular, the transition between shallow penetration, with soil heaving to the ground surface, and deep penetration, with a localised flow-round mechanism, has been investigated. This transition governs the onset of back-flow and hence the depth of soil lying on the installed spudcan, which in turn influences the bearing capacity and also the potential for suction to develop and hence the uplift capacity and moment resistance of the foundation. The maximum cavity depth above the spudcan prior to any back-flow is therefore a critical issue for spudcan assessment in clay. In the centrifuge model tests, a half-spudcan model penetrating against a transparent window has been used to visualise the soil flow mechanisms around the spudcan during penetration. The formation of a cavity above the spudcan is revealed by both centr...
TL;DR: The results of an analysis concerning a landslide of great dimensions, which occurred at Senise (Italy) on 26 July 1986, are presented in this article, and the failure developed within a thin clayey silt layer interbedded by a slightly cemented sand formation.
Abstract: The results of an analysis concerning a landslide of great dimensions, which occurred at Senise (Southern Italy) on 26 July 1986, are presented. The landslide was of a translational type, and the failure developed within a thin clayey silt layer interbedded by a slightly cemented sand formation. Both these soils experienced a pronounced strain-softening behaviour during laboratory tests. From the analyses performed using the traditional limit equilibrium approach, it has been found that the average operational resistance along the sliding surface was less than that of the peak and greater than the residual resistance deduced from the laboratory tests. As a consequence, it has been postulated that a progressive failure had occurred. Such a failure process can be appropriately studied using methods that are capable of simulating the formation and development of shear zones, where strain is localised. From a computational point of view this presents many difficulties, because the numerical procedures current...
TL;DR: The objectives of this paper are to study the variability of tolerable displacements of structures and to propose a procedure to establish probability distributions of the limiting tolerables displacements.
Abstract: The design of a geotechnical work should satisfy both the ultimate limit state and serviceability limit state requirements The limit state design approach addresses various performance requirements and aims to accommodate uncertainties At present, most limit-state design codes use reliability principles to design for ultimate limit states However, serviceability limit states are still considered in some design codes using the conventional deterministic approach To develop reliability-based serviceability criteria for more consistent design, the probability distributions of the limiting tolerable displacements should be studied The objectives of this paper are to study the variability of tolerable displacements of structures and to propose a procedure to establish probability distributions of the limiting tolerable displacements To formulate appropriate probability distributions of the limiting tolerable displacements of structures, performance information was studied and evaluated for 171 bridges an
TL;DR: In this paper, a suite of 2D and 3D finite element (FE) analyses of tunnel construction in London Clay is presented, and it is shown that even with a high degree of soil anisotropy, the transverse settlement trough remains too shallow.
Abstract: Finite element (FE) analysis is now often used in engineering practice to model tunnel-induced ground surface settlement. For initial stress regimes with a high coefficient of lateral earth pressure at rest, K0, it has been shown by several studies that the transverse settlement trough predicted by two-dimensional (2D) FE analysis is too wide when compared with field data. It has been suggested that 3D effects and/or soil anisotropy could account for this discrepancy. This paper presents a suite of both 2D and 3D FE analyses of tunnel construction in London Clay. Both isotropic and anisotropic non-linear elastic pre-yield models are employed, and it is shown that, even for a high degree of soil anisotropy, the transverse settlement trough remains too shallow. By comparing longitudinal settlement profiles obtained from 3D analyses with field data it is demonstrated that the longitudinal trough extends too far in the longitudinal direction, and that consequently it is difficult to establish steady-state set...
TL;DR: In this article, the effects of wall stiffness in different coordinate directions and the rotational fixity in the corner of the excavation are examined, and compared with the equivalent axisymmetric and plane strain analyses, normally used as approximations for modelling purposes.
Abstract: This paper investigates a number of issues related to the modelling of a retaining structure used to support an excavation in 3D finite element analyses. In particular, the effects of wall stiffness in different coordinate directions and the rotational fixity in the corner of the excavation are examined. Both square and rectangular excavations are analysed and compared with the equivalent axisymmetric and plane strain analyses, normally used as approximations for modelling purposes. The chosen geometry, construction sequence and soil conditions are based on a proposed deep excavation at Moorgate in London (next to the Moor House development), which will form part of an underground station for the Crossrail project. The objective of the study is to provide a detailed assessment of wall and ground movements and structural forces in the wall in the light of different modelling assumptions. The study has wider application to a variety of projects that include the development of infrastructure, the constructio...
TL;DR: In this article, a two-dimensional frictionless wall is designed against sliding using Rankine's earth pressure theory, and the design friction angle and unit weight values are calculated using random field simulation.
Abstract: Retaining wall design has long been carried out with the aid of either the Rankine or Coulomb theories of earth pressure. To obtain a closed-form solution, these traditional earth pressure theories assume that the soil is uniform. The fact that soils are actually spatially variable leads, however, to two potential problems in design: do sampled soil properties adequately reflect the effective properties of the entire retained soil mass, and does spatial variability of soil properties lead to active earth pressure effects that are significantly different from those predicted using traditional models? This paper combines non-linear finite element analysis with random field simulation to investigate these two questions and assess just how safe current design practice is. The specific case investigated is a two-dimensional frictionless wall retaining a cohesionless drained backfill. The wall is designed against sliding using Rankine's earth pressure theory. The design friction angle and unit weight values are...
TL;DR: In this paper, a visualisation of the evolution of crushing in a weak granular material subjected to a direct shear test is presented, where the results from direct shears conducted on sugar, and a computer simulation using the discrete element method are presented.
Abstract: Granular materials forming part of embankments, foundations and pavement structures are subjected to both static and dynamic loads. As a result, total or partial particle breakage occurs. Particle breakage causes settlements and a reduction in hydraulic conductivity (Fragaszy & Voss, 1986). Previous research has indicated that granular materials undergoing crushing exhibit a non-linear Mohr-Coulomb failure envelope if the envelope is constructed with the peak values of shear resistance. Therefore the angle of shearing resistance decreases as a consequence of particle crushing (Bolton, 1986; Feda, 2002). On the other hand, recent ring shear tests on carbonate sand presented by Coop et al. (2004) showed crushing without loss of residual angle of internal friction. It seems that crushable granular materials experience a reduction in the internal friction angle as a consequence of particle breakage prior to achieving a constant value of residual strength. The main focus of this study is to understand and produce a visualisation of the evolution of crushing in a weak granular material subjected to a direct shear test. The results from direct shear tests conducted on sugar, and a computer simulation using the discrete element method, are presented. (A)
TL;DR: In this article, a probabilistic slope analysis methodology based on Monte Carlo simulation using Microsoft Excel and @Risk software is applied to investigate the failure of the Shek Kip Mei cut in Hong Kong.
Abstract: A probabilistic slope analysis methodology based on Monte Carlo simulation using Microsoft Excel and @Risk software is applied to investigate the failure of the Shek Kip Mei cut in Hong Kong. The study demonstrates the techniques used in quantifying uncertainties in shear strength of granitic soils based on a large database of triaxial tests. Probabilistic back-analyses of the failure are applied to estimate the probability distribution of the pore water pressure. Using the back-calculated pore pressure, the inclination of the Shek Kip Mei slope is redesigned to a flatter inclination, and the probability of unsatisfactory performance and reliability index are estimated.
TL;DR: In this paper, a series of direct shear box tests were performed to characterise the strength of colluvium, under drained conditions, at vertical effective stresses between 5 and 20 kPa.
Abstract: Mobilisation of shear strength in shallow translational slips occurs at very low effective stress. Accordingly, a series of direct shear box tests was performed to characterise the strength of colluvium, under drained conditions, at vertical effective stresses between 5 and 20 kPa. Results from in situ tests on undisturbed block samples of moist soil are compared with laboratory tests on dry reconstituted specimens of the soil matrix only. The in situ tests determine a mean value of peak or maximum angle of shearing resistance between 58° and 64°, and a mean value at large displacement between 46° and 52°, with 46° believed representative of shearing at constant volume. Mobilisation of similar angles of shearing resistance, between 46° and 48°, at large displacement in laboratory tests on the 25 mm minus fraction indicates that the soil matrix is controlling strength. The values at large displacement are attributed to mineralogy, grain shape and angularity, and grain size distribution of the soils. Observ...
TL;DR: In this paper, the effect of pile diameter on the unit shaft friction that can develop on a pile in sand is examined based on a series of tension tests conducted on centrifuge model piles with a range of pile diameters and average initial stress levels.
Abstract: This paper examines the effect of pile diameter on the unit shaft friction that can develop on a pile in sand. The study is based on a series of tension tests conducted on centrifuge model piles with a range of pile diameters and average initial stress levels. The inferred significant increases in lateral effective stresses on the shafts of these piles at peak capacity are shown to be consistent with the normal displacement (dilation)–stiffness relationship measured in appropriate constant normal stiffness (CNS) interface tests. The determination of the lateral stress increases (and hence shaft capacity) also requires measurement or prediction of the non-linear cavity expansion stiffness of the sand surrounding the pile shaft. Predictions obtained for this stiffness using a numerical technique indicate that the operational stiffness surrounding a model pile is well below that assuming the very small strain (elastic) stiffness, and that the degree of normal displacement (and hence the lateral stress increa...
TL;DR: In this paper, the authors explore the applications of thermomechanics to the constitutive modelling of soils and other geomaterials, and present a series of experiments that explore the application of the modern theory of thermomachines to geomagnetworks.
Abstract: This paper is part of a series that aims to explore systematically the applications of the modern theory of thermomechanics to the constitutive modelling of soils and other geomaterials. Although t...
TL;DR: In this article, the history of Beliche Dam construction, impoundment, and rainfall was simulated by means of a coupled flow-deformation model, and the results of laboratory test results under dry and flooded conditions were interpreted, and material parameters were identified.
Abstract: Beliche Dam, a zoned earthdam with rockfill shoulders and a central clay core, experienced large collapse settlements due to reservoir impounding and direct action of rainfall. Long-term field records of vertical and horizontal displacements are available as well as a set of large-scale laboratory tests on rockfill specimens. It has been the subject of several numerical analyses that failed to capture the relevant effect of weather conditions on the behaviour of the dam. Recent developments in the constitutive modelling of rockfill allow a substantial improvement of modelling capabilities, and this is illustrated in the paper. Laboratory test results under dry and flooded conditions were interpreted, and material parameters were identified. The complete history of dam construction, impoundment and rainfall was then simulated by means of a coupled flow–deformation model. Deformations during construction and impoundment have been reproduced. Long-term deformations have consistently been related to rainfall r...
TL;DR: In this paper, the effects of depositing varying quantities of methane hydrate within a sand are investigated by reference to their shear and bulk modulus, and damping, over a range of isotropic effective stress.
Abstract: Methane hydrates are ice-like compounds that can exist only under restricted thermobaric conditions, at low temperatures or under high ambient pressure. They are important because of their potential contributions as a future source of energy, to global warming, and as a possible trigger for long run-out submarine slope instability. This paper describes laboratory experiments to synthesise disseminated methane hydrates and to characterise them under small-strain dynamic loading in the resonant column apparatus. The effects of depositing varying quantities of methane hydrate within a sand are investigated by reference to their shear and bulk modulus, and damping, over a range of isotropic effective stress. Results are compared with those obtained on the same sand without hydrate bonding and after dissociation.
TL;DR: In this article, the authors present the results of a Monte Carlo simulation incorporating many 3D single-layer soil profiles with different statistical characteristics, which is used to assess the reliability of various site investigation scopes and test methods.
Abstract: It is widely appreciated that, in civil engineering and building projects, the largest element of financial and technical risk usually lies in the ground. Almost exclusively, the scope of geotechnical investigations is governed not by what is needed to characterise the subsurface conditions appropriately but, rather, by how much the client and project manager are willing to spend. There is often little correlation between the variability of the ground and the scope of the investigation. This paper presents the results of a Monte Carlo simulation incorporating many 3D single-layer soil profiles with different statistical characteristics. A three-storey building founded on nine pad footings is used to assess the reliability of various site investigation scopes and test methods. The pad footings are designed on the basis of settlement, and are examined using 3D finite element analysis and Schmertmann's method. It is observed, as expected, that the likelihood of underdesigning or overdesigning a footing decre...
TL;DR: In this article, numerical simulations using the PFC2D program, based on discrete element method (DEM), were used to investigate the penetration resistance of driven piles in breakable weak sands is less than that of similar piles in strong sands.
Abstract: The capacity of driven piles in breakable weak sands is less than that of similar piles in strong sands. Numerical simulations using the PFC2D program, based on discrete element method (DEM), were used to investigate the penetration resistance of driven piles. The penetration resistance for an unbreakable granular material and a crushable granular material was examined. A soil composed of weak granular particles had a lower penetration resistance than a similar soil composed of uncrushab]e particles. Particle crushing caused the production of particles of different sizes. Breakage and particle rearrangement induced stress relaxation and caused the broken granular material to develop a lower resistance to pile penetration. Including a simplified tensile failure criterion in the DEM allowed crushing around piles to be analysed and visualised.
TL;DR: In this paper, a kinematic plastic solution is developed for the penetration of a circular footing into an incompressible soil bed, where the pattern of deformation around the footing is idealised by a simple plastic deformation mechanism.
Abstract: A kinematic plastic solution has been developed for the penetration of a circular footing into an incompressible soil bed. In this solution, the pattern of deformation around the footing is idealised by a simple plastic deformation mechanism. Strain-hardening behaviour and nonlinear stress–strain characteristics are incorporated. This application is different from conventional applications of plasticity theory as it can approximately predict both stresses and displacements under working conditions. This approach therefore provides a unified solution for design problems in which both serviceability and safety requirements are based directly on the stress–strain behaviour of the soil. The design strength that should limit the deformations can be selected from the actual stress–strain data recorded from a carefully specified location, and not derived using empirical safety factors. The validity of this design approach is examined against nonlinear finite element analyses and field measurements of foundations...
TL;DR: In this article, a series of numerical plane strain test simulations on a particulate material, carried out using the three-dimensional particle flow code PFC-3D, is described.
Abstract: This paper describes the results of a series of numerical plane strain test simulations on a particulate material, carried out using the three-dimensional particle flow code PFC-3D. Samples comprised about 10 000 non-spherical particles, each formed by strongly bonding two spheres together. The simulations demonstrate the ability of such a model to capture the essential macro-features of soil behaviour as observed in laboratory tests, including the dependence of peak strengths on the initial void ratio relative to the critical. The development of strain localisations or shear bands associated with the use of rough loading platens, and the sensitivity of the model to the initial sample porosity, particle shape factor and interparticle friction angle, were also investigated.
TL;DR: In this article, a site in Boissy-le-Chatel, France, has been instrumented with a meteorological station, piezometers, thermocouples and time domain reflectometry equipment, in order to monitor solar radiation.
Abstract: A site in Boissy-le-Chatel, France, has been instrumented with a meteorological station, piezometers, thermocouples and time domain reflectometry equipment, in order to monitor solar radiation ener...