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Publisher: Springer-Verlag   (Total: 2335 journals)

 Acta Geotechnica   [SJR: 1.818]   [H-I: 22]   [6 followers]  Follow         Hybrid journal (It can contain Open Access articles)    ISSN (Print) 1861-1133 - ISSN (Online) 1861-1125    Published by Springer-Verlag  [2335 journals]
• A unified mechanical and retention model for saturated and unsaturated
soil behaviour
• Authors: Martí Lloret-Cabot; Simon J. Wheeler; Marcelo Sánchez
Pages: 1 - 21
Abstract: The coupled mechanical and water retention elasto-plastic constitutive model of Wheeler, Sharma and Buisson (the Glasgow coupled model, GCM) predicts unique unsaturated isotropic normal compression and unsaturated critical state planar surfaces for specific volume and degree of saturation when soil states are at the intersection of mechanical (M) and wetting retention (WR) yield surfaces. Experimental results from tests performed by Sivakumar on unsaturated samples of compacted speswhite kaolin confirm the existence and form of these unique surfaces. The GCM provides consistent representation of transitions between saturated and unsaturated conditions, including the influence of retention hysteresis and the effect of plastic volumetric strains on retention behaviour, and it gives unique expressions to predict saturation and de-saturation conditions (air-exclusion and air-entry points, respectively). Mechanical behaviour is modelled consistently across these transitions, including appropriate variation of mechanical yield stress under both saturated and unsaturated conditions. The expressions defining the unsaturated isotropic normal compression planar surfaces for specific volume and degree of saturation are central to the development of a relatively straightforward methodology for determining values of all GCM parameters (soil constants and initial state) from a limited number of laboratory tests. This methodology is demonstrated by application to the experimental data of Sivakumar. Comparison of model simulations with experimental results for the full set of Sivakumar’s isotropic loading stages demonstrates that the model is able to predict accurately the variation of both specific volume and degree of saturation during isotropic stress paths under saturated and unsaturated conditions.
PubDate: 2017-02-01
DOI: 10.1007/s11440-016-0497-x
Issue No: Vol. 12, No. 1 (2017)

• Effect of decompression and suction on macroscopic and microscopic
behavior of a clay rock
• Authors: Xin Wei; Myriam Duc; Mahdia Hattab; Thierry Reuschlé; Said Taibi; Jean-Marie Fleureau
Pages: 47 - 65
Abstract: The goal in this research was to analyze the effects of decompression and suction on the formation of cracks in a clay rock from the Andra (French National Radioactive Waste Management Agency) site at Bure (Meuse–Haute-Marne, France). The article investigates the relationship between the changes in the hydromechanical properties and the changes in microstructure and porosity. Concerning the effect of decompression, at the macroscopic scale, the study highlighted an important effect on the elastic modulus and permeability, but little effect at the microscopic scale except an evolution of mineralogy related to the oxidation of pyrite often present in layers where cracks develop. Concerning the effect of suction, at the macroscopic level, the results showed that, on drying path, the change in the properties of the material was very small, whereas, on wetting path, a large decrease in tensile strength and gas permeability was observed. At the microscopic level, observations with SEM and ESEM, and measurements with MIP, highlighted the evolution of microstructural organization as a function of suction, and the propagation and enlargement of cracks on wetting path, rather than on drying path.
PubDate: 2017-02-01
DOI: 10.1007/s11440-016-0454-8
Issue No: Vol. 12, No. 1 (2017)

• Contact angle mechanical influence in wet granular soils
• Authors: Jérôme Duriez; Richard Wan
Pages: 67 - 83
Abstract: We investigate the macroscopic mechanical influence of the local liquid–solid contact angle that governs the fluid distribution in granular soils under unsaturated conditions. To this end, a discrete element method (DEM)-based implementation that accommodates for any contact angle is proposed and applied to an idealized granular material in the pendular regime. The DEM model includes resultant capillary forces as well as a comprehensive description of the capillary bridges (volume, surface, orientation tensor) by solving the Laplace–Young equation in a general case, instead of using any unnecessary phenomenological relation. Macroscale mechanical simulations for different constant contact angle values reveal that granular assemblies are less sensitive to unsaturated conditions for higher contact angles, which is in line with the contact angle influence at the microscopic capillary bridge scale. The contribution of the fluid mixture to the total stresses of the wet soil, the so-called capillary stresses, indeed decreases according to the contact angle. Thus, the increase in apparent shear strength due to unsaturated conditions is reduced for higher contact angles. As such, the classical assumption of perfect wetting (zero contact angle) appears to be non-conservative.
PubDate: 2017-02-01
DOI: 10.1007/s11440-016-0500-6
Issue No: Vol. 12, No. 1 (2017)

• Effects of principal stress rotation on the wave–seabed interactions
• Authors: Zhe Wang; Yunming Yang; Hai-Sui Yu
Pages: 97 - 106
Abstract: This paper simulates the wave–seabed interactions considering the principal stress rotation (PSR) by using the finite element method. The soil model is developed within the framework of kinematic hardening and the bounding surface concept, and it can properly consider the impact of PSR by treating the PSR generating stress rate independently. The simulation results are compared with centrifuge test results. The comparison indicates that the simulation with the soil model considering the PSR can better reproduce the test results on the development of pore water pressure and liquefaction than the soil model without considering the PSR. It indicates that it is important to consider the PSR impact in simulation of wave–seabed soil interactions.
PubDate: 2017-02-01
DOI: 10.1007/s11440-016-0450-z
Issue No: Vol. 12, No. 1 (2017)

• DEM assessment of impact forces of dry granular masses on rigid barriers
• Authors: Francesco Calvetti; Claudio Giulio di Prisco; Emmanouil Vairaktaris
Pages: 129 - 144
Abstract: In the design of sheltering structures/embankments for the mitigation of the risk due to rapid and long spreading landslides, a crucial role is generally played by the assessment of the impact force exerted by the flowing mass on the artificial obstacle. This paper is focused on this issue and in particular on the evaluation of the maximum impact force on the basis of the results obtained by performing an extensive numerical campaign by means of a 3D discrete element code, in which a dry granular mass is schematised as a random distribution of rigid spherical particles. The granular mass is generated just in front of the obstacle: its initial volume, velocity distribution, height, length and porosity are arbitrarily assigned, and the impact process is exclusively analysed. The initial conditions are varied to take a large variety of geometrical/mechanical factors, such as the initial front inclination, its height, the initial void ratio, the length of the impacting mass and the inter-particle friction angle, into consideration. A design formula is also proposed on the base of the obtained results and critically compared with the literature data.
PubDate: 2017-02-01
DOI: 10.1007/s11440-016-0434-z
Issue No: Vol. 12, No. 1 (2017)

• Strain responses of frozen clay with thermal gradient under triaxial creep
• Authors: Xiaodong Zhao; Guoqing Zhou; Guilin Lu
Pages: 183 - 193
Abstract: Thermal gradient is one of the main features for the temperature distribution in artificial frozen shaft lining (FSL). The time-dependent strain responses and the corresponding heterogeneity characteristics of frozen soils with thermal gradient are of potential significance for stability assessment and prediction of FSL, especially of the FSL embedded in thick alluvium. A series of triaxial creep tests were carried out on frozen saturated clay under various thermal gradients and creep stresses. The experimental results indicated that the triaxial creep curves for frozen clay with thermal gradient exhibit viscous characteristics, and the creep rate $$\Delta \varepsilon_{\text{a}} /\Delta t$$ decreases with the increase in creep time $$t$$ and decrease in thermal gradient. The stress–strain curve under different $$t$$ showed that the creep stress has a marked growth when axial strain $$\varepsilon_{\text{a}} \le 1\,\%$$ . However, when $$\varepsilon_{\text{a}} \ge 1\,\%$$ , the growth rate decreases gradually. The deviation between measured radial strain $$\varepsilon_{\text{r}}^{\text{m}}$$ under the middle specimen section height SSH and the calculated radial strain $$\varepsilon_{\text{r}}^{\text{c}}$$ from the volumetric strain increases following a unified equation with the increase in axial strain. The radial strain $$\varepsilon_{\text{r}}^{\text{f}}$$ for frozen clay with thermal gradient after experiment increases with the increase in SSH, and the slope of $$\varepsilon_{\text{r}}^{\text{f}} - {\text{SSH}}$$ curve is significantly dependent on the thermal gradient and creep stress. The variation of $$\varepsilon_{\text{r}}^{\text{m}} - \varepsilon_{\text{r}}^{\text{c }}$$ during experiment and $$\varepsilon_{\text{r}}^{\text{f}}$$ distribution after experiment are the macro-responses of internal micro-heterogeneities in frozen soils induced from thermal gradient, and are closely related to strain rate and its variation. These observations and findings provide an insight into the creep mechanism and the estimation method of creep deformation for frozen soils with thermal gradient.
PubDate: 2017-02-01
DOI: 10.1007/s11440-015-0424-6
Issue No: Vol. 12, No. 1 (2017)

• Numerical study of partially drained penetration and pore pressure
dissipation in piezocone test
• Authors: Francesca Ceccato; Paolo Simonini
Pages: 195 - 209
Abstract: The piezocone penetration test (CPTU) is commonly used as a fast and economical tool to identify soil profile and to estimate relevant material properties in soils ranging from fine to coarse-grained. Moreover, in the case of fine-grained soils (clays and silts), the consolidation coefficient and the permeability can be estimated through the dissipation test. Undrained conditions are commonly assumed for the interpretation of CPTU in fine-grained soils, but in soils such as silts, penetration may occur in partially drained conditions. This aspect is often neglected in data interpretation thus leading to an inaccurate estimate of soil properties. This paper investigates numerically the effect of partial drainage during penetration on the measured tip resistance and the subsequent pore pressure dissipation response contributing to a more accurate interpretation of field data. A realistic simulation of the cone penetration is achieved with the two-phase Material Point Method, modelling the soil response with the modified Cam-Clay model. The approach takes into account large soil deformations induced by the advancing cone, soil–water, and soil–structure interactions, as well as nonlinear soil behavior.
PubDate: 2017-02-01
DOI: 10.1007/s11440-016-0448-6
Issue No: Vol. 12, No. 1 (2017)

• A monotonic bounding surface critical state model for clays
• Authors: Jinbo Chen
Pages: 225 - 230
Abstract: This study investigates a simple constitutive model based on the critical state framework and bounding surface (BS) plasticity that is suitable for reconstituted clays over a wide range of overconsolidation ratios under monotonic loading. For heavily overconsolidated (OC) clays, rather than using the conventional Hvorslev line, an empirical surface is introduced into the model formulation based on two image points on the BS. The peak strength and the dilatancy of heavily OC clays can thus be predicted satisfactorily. Comparisons with triaxial test data show that the model well captures the peak strength and the dilatancy of heavily OC clays under monotonic loading.
PubDate: 2017-02-01
DOI: 10.1007/s11440-016-0439-7
Issue No: Vol. 12, No. 1 (2017)

• Three-dimensional DEM investigation of critical state and dilatancy
behaviors of granular materials
• Authors: Wei Zhou; Jiaying Liu; Gang Ma; Xiaolin Chang
Abstract: The critical state is significant to the mechanical behaviors of granular materials and the foundation of the constitutive relations. Using the discrete element method (DEM), the mechanical behaviors of granular materials can be investigated on both the macroscopic and microscopic levels. A series of DEM simulations under true triaxial conditions have been performed to explore the critical state and dilatancy behavior of granular materials, which show the qualitatively similar macroscopic responses as the experimental results. The critical void ratio and stress ratio under different stress paths are presented. A unique critical state line (CSL) is shown to indicate that the intermediate principal stress ratio does not influence the CSL. Within the framework of the unique critical state, the stress–dilatancy relation of DEM simulations is found to fulfill the state-dependent dilatancy equations. As a microscopic parameter to evaluate the static determinacy of the granular system, the redundancy ratio is defined and investigated. The results show that the critical state is very close to the statically determinate state. Other particle-level indexes, including the distribution of the contact forces and the anisotropies, are carefully investigated to analyze the microstructural evolution and the underlying mechanism. The microscopic analysis shows that both the contact orientations and contact forces influence the mechanical behaviors of granular materials.
PubDate: 2017-03-17
DOI: 10.1007/s11440-017-0530-8

• Tide-induced hydraulic response in a semi-infinite seabed with a
subaqueous drained tunnel
• Authors: Hongwei Ying; Chengwei Zhu; Xiaonan Gong
Abstract: In this study, analytical solutions for tide-induced pore pressure, seepage force and water inflow into a subaqueous drained tunnel are developed. The results are compared with numerical solutions from a commercial software. The effects of the soil permeability, shear modulus, lining thickness and buried depth of the tunnel on tide-induced pore pressure, seepage force and water inflow are discussed. Larger tide-induced pore pressure and seepage force are obtained for smaller tunnel depth and higher soil permeability. The phase lags of the maximal tide-induced pore pressure at different depths are determined and investigated.
PubDate: 2017-03-15
DOI: 10.1007/s11440-017-0525-5

• A generalized nonlinear failure criterion for frictional materials
• Authors: Shunchuan Wu; Shihuai Zhang; Chao Guo; Liangfeng Xiong
Abstract: A generalized nonlinear failure criterion formulated in terms of stress invariants is proposed for describing the failure characteristics of different frictional materials. This failure criterion combines a power function and a versatile function in the meridian and deviatoric plane, respectively, which is a generalization of several classic criteria, including the Tresca, Drucker–Prager, Mohr–Coulomb, Lade–Duncan and Matsuoka–Nakai failure criterion. The procedure for determination of the strength parameters was demonstrated in detail. Comparisons between the failure criterion and experimental results were presented for uncemented/cemented Monterey sand, normally consolidated Fujinomori clay, rockfill, concrete, Mu-San sandstone and granite, which reveal that the proposed failure criterion captures experimental trend quite well.
PubDate: 2017-03-13
DOI: 10.1007/s11440-017-0532-6

• Stress–strain behavior of cement-improved clays: testing and
modeling
• Authors: Allison J. Quiroga; Zachary M. Thompson; Kanthasamy K. Muraleetharan; Gerald A. Miller; Amy B. Cerato
Abstract: The results of a series of laboratory tests on unimproved and cement-improved specimens of two clays are presented, and the ability of a bounding surface elastoplastic constitutive model to predict the observed behavior is investigated. The results of the oedometer, triaxial compression, extension, and cyclic shear tests demonstrated that the unimproved soil behavior is similar to that of soft clays. Cement-improved specimens exhibited peak/residual behavior and dilation, as well as higher strength and stiffness over unimproved samples in triaxial compression. Two methods of accounting for the artificial overconsolidation effect created by cement improvement are detailed. The apparent preconsolidation pressure method is considerably easier to use, but the fitted OCR method gave better results over varied levels of confining stresses. While the bounding surface model predicted the monotonic behavior of unimproved soil very well, the predictions made for cyclic behavior and for improved soils were only of limited success.
PubDate: 2017-03-10
DOI: 10.1007/s11440-017-0529-1

• Analysis of size effects on the geomechanical parameters of intact granite
samples under unconfined conditions
• Authors: J. Quiñones; J. Arzúa; L. R. Alejano; F. García-Bastante; D. Mas Ivars; G. Walton
Abstract: A total of 28 uniaxial compressive strength tests were performed on cylindrical Blanco Mera granite samples with diameters ranging between 14 and 100 mm, with results indicating that this granite undergoes a significant reverse size effect: the UCS increases as sample diameter increases up to 54 mm, but thereafter decreases. It was also found that the results tend to be more scattered for smaller sample diameters. We also found an apparent correlation between Young’s modulus and sample diameter. It was not possible to draw any clear conclusions regarding the variability in Poisson’s ratio with sample size. With respect to crack initiation and crack damage stresses, the behaviour of the tested samples also indicates a reverse effect. This research would suggest that the traditionally assumed decrease in strength as sample size increases does not hold for granite samples with diameters below 54 mm.
PubDate: 2017-03-07
DOI: 10.1007/s11440-017-0531-7

• Use of discrete element modeling to study the stress and strain
distribution in cyclic torsional shear tests
• Authors: José Francisco Wilson; Esteban Sáez
Abstract: In this research, a torsional cyclic shear test was modeled using the 3D discrete element method (DEM). The results are compared against experimental data and micro-mechanical aspects of the soil during the loading are discussed. The aim of the work is to study the homogeneity of strains during this laboratory test and to compare the micro-mechanical behavior of the soil sample for different strain levels. The experimental investigation was performed using a synthetic soil material made of glass beads, which simplifies the modeling and calibration since normal interaction forces do not induce rotation of the particles. Both the model and experimental tests used the same grading distribution and particle size. We showed that the hysteresis cycles can be properly reproduced in terms of shape and magnitude. Thus, we obtained a robust estimation for the secant shear modulus and damping ratio at different strain levels. With this, it was possible to build stiffness degradation and damping increase curve to compare it with experimental data obtained from torsional shear tests. Based on this validation of the DEM model, we discuss the micro-mechanical behavior of the soil and its relation with the macroscopic parameters obtained. It is shown that shear strain distribution on the sample is not uniform and that large values of strains concentrate close to the top of the sample as top rotation increases, which differs from the standard assumption of a constant value across the height of the sample. Additionally, it is observed that at 0.8 times radius, the cumulative torque reaches approximately 90% of the total torque applied to sample.
PubDate: 2017-03-04
DOI: 10.1007/s11440-017-0526-4

• Global representation of the drying–wetting curves of four engineering
soils: experiments and correlations
• Authors: Zhong-Sen Li; Assia Benchouk; Feth-Ellah Mounir Derfouf; Nabil Abou-Bekr; Said Taibi; Hanène Souli; Jean-Marie Fleureau
Abstract: The main objective of this paper is to examine how different engineering soils react to environmental variations and to provide correlations to characterize their behaviour under null external mechanical stress. Two French and two Algerian soils with liquid limits ranging from 36 to 112 were prepared under both slurry and Proctor compaction conditions, and then subjected to drying–wetting paths with suction controlled from several kPa to several hundreds of MPa. Experimental results are presented in five diagrams to show globally and simultaneously the shrinkage–swelling, saturation–desaturation and water retention characteristics. A reasonable consistency was observed between the oedometric and drying curves of slurry, confirming the equivalence between hydraulic loading (suction) and mechanical loading (consolidation stress) on the volume change behaviour of different soils. As an intrinsic parameter of soil nature, liquid limit was found to have a significant influence on the shrinkage limit, air-entry suction and compressibility of both slurry and compacted samples. For that reason, correlations between these characteristics and liquid limit were set up, providing a good basis for a first estimation of the drying–wetting curves. At the micro-scale, new experimental results were obtained: either on drying or wetting path, the micro-pores were almost unaffected, whereas, when matrix suction increased from 0.1 to 8 MPa, the volume of macro-pores decreased to quasi-closure. At last, the analogy between the compaction and drying–wetting curves, and the comparison of different methods to determine the water retention curve were addressed. Such analogies and comparisons contribute to a better understanding of the mechanisms of mechanical stress and suction.
PubDate: 2017-02-24
DOI: 10.1007/s11440-017-0527-3

• Fines adsorption on nanoparticle-coated surface
• Authors: Xianglei Zheng; François Perreault; Jaewon Jang
Abstract: Fluid flow through porous media is inherently associated with the detachment and migration of fine particles. The migration of fine particles and ensuing clogging is the main reason of flow rate decrease in porous media. Nanoparticle coating can be a promising method to prevent fines’ detachment and migration by changing electrical surface forces between the pore wall surface and the fine particles. In this study, the attraction and adhesion forces of the nanoparticle-coated surface are measured by atomic force microscope. The effect of the nanoparticle coating on the fines adsorption efficiency is then investigated. The results show that there is an increase in the adhesion force on the nanoparticle-coated surface and the significant improvement of the fines adsorption capacity by the nanoparticle coating. The research results are relevant to other research areas whenever migrating fines cause engineering problems.
PubDate: 2017-02-23
DOI: 10.1007/s11440-017-0528-2

• Seasonal effects on geophysical–geotechnical relationships and their
implications for electrical resistivity tomography monitoring of slopes
• Authors: R. M. Hen-Jones; P. N. Hughes; R. A. Stirling; S. Glendinning; J. E. Chambers; D. A. Gunn; Y. J. Cui
Abstract: Current assessments of slope stability rely on point sensors, the results of which are often difficult to interpret, have relatively high costs and do not provide large-area coverage. A new system is under development, based on integrated geophysical–geotechnical sensors to monitor groundwater conditions via electrical resistivity tomography. So that this system can provide end users with reliable information, it is essential that the relationships between resistivity, shear strength, suction and water content are fully resolved, particularly where soils undergo significant cycles of drying and wetting, with associated soil fabric changes. This paper presents a study to establish these relationships for a remoulded clay taken from a test site in Northumberland, UK. A rigorous testing programme has been undertaken, integrating the results of multi-scalar laboratory and field experiments, comparing two-point and four-point resistivity testing methods. Shear strength and water content were investigated using standard methods, whilst a soil water retention curve was derived using a WP4 dewpoint potentiometer. To simulate seasonal effects, drying and wetting cycles were imposed on prepared soil specimens. Results indicated an inverse power relationship between resistivity and water content with limited hysteresis between drying and wetting cycles. Soil resistivity at lower water contents was, however, observed to increase with ongoing seasonal cycling. Linear hysteretic relationships were established between undrained shear strength and water content, principally affected by two mechanisms: soil fabric deterioration and soil suction loss between drying and wetting events. These trends were supported by images obtained from scanning electron microscopy.
PubDate: 2017-02-15
DOI: 10.1007/s11440-017-0523-7

• Numerical simulations of the reuse of piled raft foundations in clay
• Authors: Brian Sheil
Abstract: The development and growth of urban environments in recent years is requiring geotechnical engineers to consider foundation reuse as a more sustainable solution to inner city redevelopment. Two main phenomena associated with foundation reuse have been reported in the literature, namely ‘preloading effects’ and ‘ageing effects’. The aim of this paper is to investigate the relative merits of these effects on the reusability of both piled and unpiled raft foundations in clay. Finite element analysis, in conjunction with an isotropic elasto-viscoplastic soil model, is employed for this purpose. The study is presented in two phases: (1) evaluation of preloading effects only by using a very low creep coefficient and (2) evaluation of combined preloading and creep effects. The variables considered in the parametric study include the number of piles, pile spacing, pile length, and soil type. Results show that both unpiled and piled rafts can exhibit significant capacity and stiffness increases upon reloading even for moderate levels of preload. Moreover, these increases are strongly dependent on the piled raft load sharing where unpiled raft and free-standing pile group capacity gains serve as upper and lower bounds, respectively, for that of a piled raft. This study underlines foundations reuse as an effective and sustainable solution for inner city redevelopment.
PubDate: 2017-02-06
DOI: 10.1007/s11440-017-0522-8

• Centroid sliding pyramid method for removability and stability analysis of
fractured hard rock
• Authors: Wei Wu; Xiaoying Zhuang; Hehua Zhu; Xingen Liu; Guowei Ma
Abstract: This paper proposes a new method using centroid sliding pyramid (CSP) to identify the removability and stability of fractured hard rock in tunnel and slope engineering. The new method features two geometrical and topological improvements over the original key block method (KBM). Firstly, all the concave corners are considered as starting points of cutting process when a concave block is divided into a set of convex blocks in the original KBM. Only the concave corners formed by two joint planes are used for partitioning a concave block in the presented method and concave corners with free planes are excluded. Secondly, joint pyramid for removability computation in the original KBM is generated using all of the joint planes, while CSP is calculated only from the joint planes adjoining the free planes. The cone angle θ of CSP is the vectorial angle formed by the two candidate sliding surfaces of this CSP. Removability analysis of a block is transformed into calculating the cone angle of CSP. The geometrical relationship is simplified, and data size for removability computation is reduced compared with the original KBM. The provided method is implemented in a computer program and validated by examples of fractured rock slopes and tunnels.
PubDate: 2017-02-02
DOI: 10.1007/s11440-016-0510-4

• Field testing of one-way and two-way cyclic lateral responses of single
and jet-grouting reinforced piles in soft clay
• Authors: Ben He; Lizhong Wang; Yi Hong
PubDate: 2017-02-01
DOI: 10.1007/s11440-016-0515-z

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