Dépouillements

Modelling time-dependent behaviour of Murro test embankment / M. Karstunen in Géotechnique, Vol. 60 N° 10 (Octobre 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 735-749 Titre : Modelling time-dependent behaviour of Murro test embankment Type de document : texte imprimé Auteurs : M. Karstunen, Auteur ; Yin, Z. Y., Auteur Année de publication : 2011 Article en page(s) : pp. 735-749 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Anisotropy  Clays  Numerical  modelling  Time  dependence  Embankments  Constitutive  relations Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This paper investigates the time-dependent behaviour of Murro test embankment in Finland. The embankment was built in 1993 on a soft natural clay deposit, which exhibits large strain anisotropy, destructuration and viscosity. The study is based on extensive experimental data from triaxial and oedometer tests on intact and reconstituted soil samples which shed light on the influence of time on mechanical properties, including testing designed for studying soil anisotropy and destructuration. The interpretation of the results is done in the framework of a recently developed elasto-viscoplastic model EVP-SCLAY1S, which is used to simulate the soft soil deposit coupled with Biot's consolidation theory. The determination of model parameters from the test results demonstrates that the model can be relatively easily used for practical applications. Using these parameters, two-dimensional finite-element analyses have been made as large deformation analysis. The comparisons between calculations and measurements demonstrate that the proposed model can be satisfactorily used to describe the time-dependent behaviour of the embankment on structured clay. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.027 [article] Modelling time-dependent behaviour of Murro test embankment [texte imprimé] / M. Karstunen, Auteur ; Yin, Z. Y., Auteur . - 2011 . - pp. 735-749. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 735-749 Mots-clés : Anisotropy  Clays  Numerical  modelling  Time  dependence  Embankments  Constitutive  relations Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This paper investigates the time-dependent behaviour of Murro test embankment in Finland. The embankment was built in 1993 on a soft natural clay deposit, which exhibits large strain anisotropy, destructuration and viscosity. The study is based on extensive experimental data from triaxial and oedometer tests on intact and reconstituted soil samples which shed light on the influence of time on mechanical properties, including testing designed for studying soil anisotropy and destructuration. The interpretation of the results is done in the framework of a recently developed elasto-viscoplastic model EVP-SCLAY1S, which is used to simulate the soft soil deposit coupled with Biot's consolidation theory. The determination of model parameters from the test results demonstrates that the model can be relatively easily used for practical applications. Using these parameters, two-dimensional finite-element analyses have been made as large deformation analysis. The comparisons between calculations and measurements demonstrate that the proposed model can be satisfactorily used to describe the time-dependent behaviour of the embankment on structured clay. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.027

Influence of strain rate and acceleration on the behaviour of reconstituted clays at small strains / K. K. Sorensen in Géotechnique, Vol. 60 N° 10 (Octobre 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 751-763 Titre : Influence of strain rate and acceleration on the behaviour of reconstituted clays at small strains Type de document : texte imprimé Auteurs : K. K. Sorensen, Auteur ; B. A. Baudet, Auteur ; B. Simpson, Auteur Année de publication : 2011 Article en page(s) : pp. 751-763 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Clays  Stiffness  Time  dependence  Laboratory  tests  Dynamics  Creep Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This paper attempts to bridge the gap between the well-known characteristics of strain rate-independent elastic stiffness and of the time-dependent behaviour of clays at large strains. Effects of acceleration, strain rate and ageing are examined in the very small to small strain region, using results from tests on reconstituted London Clay and kaolin. Static measurements of the shear modulus at small strains, using local instrumentation, indicate that the shear modulus is rate-independent when the soil is subjected to elastic deformations only. Most often, in practice, soil specimens are left to rest between the compression and shearing stages, until deformations associated with creep become negligible. The testing strain rate imposed upon shearing induces a temporary acceleration of strains, which results in very high measured stiffnesses. Test data show, however, that when the shearing axial strain rate is of the same order of magnitude as that measured at the end of the compression/creep stage, the remaining plastic creep strains influence the measured stiffness, which is then measured to be comparatively low. Test data also seem to show that temporary strain acceleration may hide effects of recent stress path rotation. Additionally, bender element tests were performed during isotropic compression tests with changes in stress rate and creep stages. The data indicate that the strain rate affects the value of the dynamic shear modulus of the soil. It is suggested that the increase in dynamic shear modulus during short-term creep is caused by mechanisms linked to the gradual decrease in strain rate during creep, but further investigation would be needed to clarify which physical mechanisms. A new method to account for strain rate in evaluating the dynamic shear modulus of normally consolidated reconstituted clays is finally proposed. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.07.d.147 [article] Influence of strain rate and acceleration on the behaviour of reconstituted clays at small strains [texte imprimé] / K. K. Sorensen, Auteur ; B. A. Baudet, Auteur ; B. Simpson, Auteur . - 2011 . - pp. 751-763. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 751-763 Mots-clés : Clays  Stiffness  Time  dependence  Laboratory  tests  Dynamics  Creep Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This paper attempts to bridge the gap between the well-known characteristics of strain rate-independent elastic stiffness and of the time-dependent behaviour of clays at large strains. Effects of acceleration, strain rate and ageing are examined in the very small to small strain region, using results from tests on reconstituted London Clay and kaolin. Static measurements of the shear modulus at small strains, using local instrumentation, indicate that the shear modulus is rate-independent when the soil is subjected to elastic deformations only. Most often, in practice, soil specimens are left to rest between the compression and shearing stages, until deformations associated with creep become negligible. The testing strain rate imposed upon shearing induces a temporary acceleration of strains, which results in very high measured stiffnesses. Test data show, however, that when the shearing axial strain rate is of the same order of magnitude as that measured at the end of the compression/creep stage, the remaining plastic creep strains influence the measured stiffness, which is then measured to be comparatively low. Test data also seem to show that temporary strain acceleration may hide effects of recent stress path rotation. Additionally, bender element tests were performed during isotropic compression tests with changes in stress rate and creep stages. The data indicate that the strain rate affects the value of the dynamic shear modulus of the soil. It is suggested that the increase in dynamic shear modulus during short-term creep is caused by mechanisms linked to the gradual decrease in strain rate during creep, but further investigation would be needed to clarify which physical mechanisms. A new method to account for strain rate in evaluating the dynamic shear modulus of normally consolidated reconstituted clays is finally proposed. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.07.d.147

Coupled deformation–flow analysis for methane hydrate extraction / A. Klar in Géotechnique, Vol. 60 N° 10 (Octobre 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 765-776 Titre : Coupled deformation–flow analysis for methane hydrate extraction Type de document : texte imprimé Auteurs : A. Klar, Auteur ; K. Soga, Auteur ; M. Y. A. Ng, Auteur Année de publication : 2011 Article en page(s) : pp. 765-776 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Water  flow  Groundwater  Shear  strength  Stress  analysis  Deformation  Permeability  Sands  Constitutive  relations Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Methane hydrate is estimated to be present in substantial amounts below deep sea floors. Particular scientific and engineering interests that encourage studies of mechanical behaviour of methane hydrate soils include submarine geohazards, such as the initiation of marine landslides through hydrate dissociation, wellbore stability and estimation of future gas production from wells. To study these problems, a formulation of a multi-physics model of methane hydrate flow coupled to soil deformation is developed. By assuming deformable porous media (soil matrix) that accommodate non-movable but dissociable hydrate, a two-phase flow formulation of water and methane gas is suggested according to Darcy's law and capillary pressure law. A single-phase elastic–perfectly plastic constitutive model for hydrate soil sediments, based on the concept of effective stress, is developed to account for the effect of hydrate saturation on mechanical strength and stiffness. The formulation is incorporated into the explicit scheme of finite-difference code FLAC by solving three boundary value problems in parallel. The code is used to simulate the behaviour of horizontal unsupported and supported wells in hydrate-bearing sediments under different in situ stress conditions during methane hydrate extraction. Axial force, bending moment and well displacements were compared for supported and unsupported wells. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.079-3799 [article] Coupled deformation–flow analysis for methane hydrate extraction [texte imprimé] / A. Klar, Auteur ; K. Soga, Auteur ; M. Y. A. Ng, Auteur . - 2011 . - pp. 765-776. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 765-776 Mots-clés : Water  flow  Groundwater  Shear  strength  Stress  analysis  Deformation  Permeability  Sands  Constitutive  relations Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Methane hydrate is estimated to be present in substantial amounts below deep sea floors. Particular scientific and engineering interests that encourage studies of mechanical behaviour of methane hydrate soils include submarine geohazards, such as the initiation of marine landslides through hydrate dissociation, wellbore stability and estimation of future gas production from wells. To study these problems, a formulation of a multi-physics model of methane hydrate flow coupled to soil deformation is developed. By assuming deformable porous media (soil matrix) that accommodate non-movable but dissociable hydrate, a two-phase flow formulation of water and methane gas is suggested according to Darcy's law and capillary pressure law. A single-phase elastic–perfectly plastic constitutive model for hydrate soil sediments, based on the concept of effective stress, is developed to account for the effect of hydrate saturation on mechanical strength and stiffness. The formulation is incorporated into the explicit scheme of finite-difference code FLAC by solving three boundary value problems in parallel. The code is used to simulate the behaviour of horizontal unsupported and supported wells in hydrate-bearing sediments under different in situ stress conditions during methane hydrate extraction. Axial force, bending moment and well displacements were compared for supported and unsupported wells. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.079-3799

Evaluation of the viscous behaviour of clay using generalised overstress viscoplastic theory / G. Qu in Géotechnique, Vol. 60 N° 10 (Octobre 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 777-789 Titre : Evaluation of the viscous behaviour of clay using generalised overstress viscoplastic theory Type de document : texte imprimé Auteurs : G. Qu, Auteur ; S. D. Hinchberger, Auteur ; K. Y. Lo, Auteur Année de publication : 2011 Article en page(s) : pp. 777-789 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Shear  strength  Clays  Time  dependence Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : In this paper, generalised elastic-viscoplastic (EVP) theory combined with a power law is used to derive simplified equations relating undrained shear strength and preconsolidation pressure to strain rate. An additional equation is derived relating the strain-rate parameter in EVP theory to the secondary compression index. The derived equations are used to evaluate the rate-sensitive and drained creep response of 20 clays reported in the literature. The evaluation shows strong evidence that the rate-sensitivity and time-dependency of clay in compression can be described simultaneously using the generalised EVP theory and power law. In addition, the constitutive parameter governing rate-sensitivity in EVP theory appears to be unique for constant rate-of-strain tests such as undrained triaxial compression and drained oedometer compression as well as stress controlled tests such as drained oedometer creep. To conclude, an approach to select the viscous parameters for clay is provided. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.031 [article] Evaluation of the viscous behaviour of clay using generalised overstress viscoplastic theory [texte imprimé] / G. Qu, Auteur ; S. D. Hinchberger, Auteur ; K. Y. Lo, Auteur . - 2011 . - pp. 777-789. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 777-789 Mots-clés : Shear  strength  Clays  Time  dependence Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : In this paper, generalised elastic-viscoplastic (EVP) theory combined with a power law is used to derive simplified equations relating undrained shear strength and preconsolidation pressure to strain rate. An additional equation is derived relating the strain-rate parameter in EVP theory to the secondary compression index. The derived equations are used to evaluate the rate-sensitive and drained creep response of 20 clays reported in the literature. The evaluation shows strong evidence that the rate-sensitivity and time-dependency of clay in compression can be described simultaneously using the generalised EVP theory and power law. In addition, the constitutive parameter governing rate-sensitivity in EVP theory appears to be unique for constant rate-of-strain tests such as undrained triaxial compression and drained oedometer compression as well as stress controlled tests such as drained oedometer creep. To conclude, an approach to select the viscous parameters for clay is provided. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.031

The mechanics of fibre-reinforced sand / A. P. S. Santos in Géotechnique, Vol. 60 N° 10 (Octobre 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 791-799 Titre : The mechanics of fibre-reinforced sand Type de document : texte imprimé Auteurs : A. P. S. Santos, Auteur ; N. C. Consoli, Auteur ; B. A. Baudet, Auteur Année de publication : 2011 Article en page(s) : pp. 791-799 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Reinforced  soils  Sands  Laboratory  tests Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Fibres can be an effective means of reinforcing soils. This paper presents data from laboratory triaxial tests on quartzitic sand reinforced with polypropylene fibres. By keeping the studied composite consistent throughout the study (host sand and fibre characteristics kept constant), it has been possible to develop a framework of behaviour for the sand–fibre material, which provides a solid base for future research on fibre-reinforced soils. Data from previous work and from new tests have been analysed within the Critical State framework, that is in terms of normal compression line, critical state line and state boundary surface. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.159 [article] The mechanics of fibre-reinforced sand [texte imprimé] / A. P. S. Santos, Auteur ; N. C. Consoli, Auteur ; B. A. Baudet, Auteur . - 2011 . - pp. 791-799. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 791-799 Mots-clés : Reinforced  soils  Sands  Laboratory  tests Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : Fibres can be an effective means of reinforcing soils. This paper presents data from laboratory triaxial tests on quartzitic sand reinforced with polypropylene fibres. By keeping the studied composite consistent throughout the study (host sand and fibre characteristics kept constant), it has been possible to develop a framework of behaviour for the sand–fibre material, which provides a solid base for future research on fibre-reinforced soils. Data from previous work and from new tests have been analysed within the Critical State framework, that is in terms of normal compression line, critical state line and state boundary surface. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.8.p.159

An upper-bound solution for the undrained bearing capacity of strip footings at the top of a slope / K. Georgiadis in Géotechnique, Vol. 60 N° 10 (Octobre 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 801–806 Titre : An upper-bound solution for the undrained bearing capacity of strip footings at the top of a slope Type de document : texte imprimé Auteurs : K. Georgiadis, Auteur Année de publication : 2011 Article en page(s) : pp. 801–806 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Plasticity  Footings/foundations  Limit  state  design/analysis  Bearing  capacity  Slopes Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : An analytical upper-bound plasticity solution is presented for the calculation of the undrained bearing capacity of strip footings on or near slopes. Typical results, presented in terms of the undrained bearing capacity factor, are shown to be in excellent agreement with finite-element analysis results and generally more conservative than those obtained from other available solutions. The proposed upper-bound solution is used to investigate the influence of the slope angle, the distance of the footing from the slope, the footing width and the soil properties on the undrained bearing capacity. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.09.t.016 [article] An upper-bound solution for the undrained bearing capacity of strip footings at the top of a slope [texte imprimé] / K. Georgiadis, Auteur . - 2011 . - pp. 801–806. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 801–806 Mots-clés : Plasticity  Footings/foundations  Limit  state  design/analysis  Bearing  capacity  Slopes Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : An analytical upper-bound plasticity solution is presented for the calculation of the undrained bearing capacity of strip footings on or near slopes. Typical results, presented in terms of the undrained bearing capacity factor, are shown to be in excellent agreement with finite-element analysis results and generally more conservative than those obtained from other available solutions. The proposed upper-bound solution is used to investigate the influence of the slope angle, the distance of the footing from the slope, the footing width and the soil properties on the undrained bearing capacity. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.09.t.016

A dynamical systems-based approach to soil shear / P. G. Joseph in Géotechnique, Vol. 60 N° 10 (Octobre 2010) 

Public ISBD [article]  in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 807–812 Titre : A dynamical systems-based approach to soil shear Type de document : texte imprimé Auteurs : P. G. Joseph, Auteur Année de publication : 2011 Article en page(s) : pp. 807–812 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Constitutive  relations  Clays  Plasticity  Sands  Elasticity  Silts Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This note models monotonic soil shear as a dynamical system. It provides additional information to support the hypothesis that for monotonic soil shear, the rates of change of the shear stress, effective normal stress and void ratio are proportional to the applied shear and effective normal stresses with the proportionality values decaying with strain to become zero at the steady-state condition. This hypothesis provides close fits to stress–strain–void ratio curves from undrained shear tests of uncemented, resedimented clays and drained shear tests of uncemented sands and silts, using triaxial and true-triaxial equipment, and various stress paths. For undrained shear, model parameters vary smoothly with over-consolidation ratio; for drained shear, they vary in an orderly way with relative density. The model's value lies in that a well-formed hypothesis, derived from the steady-state condition, provides a simple, alternative approach to current complex elastoplastic models based on critical state theory. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.001 [article] A dynamical systems-based approach to soil shear [texte imprimé] / P. G. Joseph, Auteur . - 2011 . - pp. 807–812. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 60 N° 10 (Octobre 2010) . - pp. 807–812 Mots-clés : Constitutive  relations  Clays  Plasticity  Sands  Elasticity  Silts Index. décimale : 624 Constructions du génie civil et du bâtiment. Infrastructures. Ouvrages en terres. Fondations. Tunnels. Ponts et charpentes Résumé : This note models monotonic soil shear as a dynamical system. It provides additional information to support the hypothesis that for monotonic soil shear, the rates of change of the shear stress, effective normal stress and void ratio are proportional to the applied shear and effective normal stresses with the proportionality values decaying with strain to become zero at the steady-state condition. This hypothesis provides close fits to stress–strain–void ratio curves from undrained shear tests of uncemented, resedimented clays and drained shear tests of uncemented sands and silts, using triaxial and true-triaxial equipment, and various stress paths. For undrained shear, model parameters vary smoothly with over-consolidation ratio; for drained shear, they vary in an orderly way with relative density. The model's value lies in that a well-formed hypothesis, derived from the steady-state condition, provides a simple, alternative approach to current complex elastoplastic models based on critical state theory. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.9.p.001

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