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Modelling diffuse instabilities in sands under drained conditions / A.M. Ramos in Géotechnique, Vol. 62 N° 6 (Juin 2012) 

Public ISBD [article]  in Géotechnique > Vol. 62 N° 6 (Juin 2012) . - pp. 471 –478 Titre : Modelling diffuse instabilities in sands under drained conditions Type de document : texte imprimé Auteurs : A.M. Ramos, Auteur ; J. E. Andrade, Auteur ; A. Lizcano, Auteur Année de publication : 2012 Article en page(s) : pp. 471 –478 Note générale : Génie Civil Langues : Anglais (eng) Mots-clés : Sands  Failure  Numerical  modelling  Theoretical  analysis  Plasticity Résumé : This paper presents a criterion for detecting diffuse (homogeneous) instabilities in granular soils sheared under fully drained conditions. The criterion is based on bifurcation theory and applied to elasto-plasticity by allowing multiple incremental solutions in elasto-plastic soils, physically losing controllability of stress boundary conditions. Drained diffuse instabilities are poorly understood, and are induced by kinematic modes different from those observed in shear bands and liquefaction instabilities. Unlike shear bands, diffuse instabilities occur under fairly homogenous deformation modes and, unlike liquefaction, drained instabilities are not generated by the excess pore pressures. Recent experiments under drained constant shear report sudden homogeneous instabilities in samples of relatively dense and loose sands. The criterion presented in this paper is used in conjunction with an elasto-plasticity model for sands to predict and explain these reported drained instabilities. From a practical standpoint, these developments serve to expand the repertoire of potential instabilities that occur well before failure, and which have been reported in case studies of puzzling slope instability failures under fully drained conditions. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.10.P.109 [article] Modelling diffuse instabilities in sands under drained conditions [texte imprimé] / A.M. Ramos, Auteur ; J. E. Andrade, Auteur ; A. Lizcano, Auteur . - 2012 . - pp. 471 –478. Génie Civil Langues : Anglais (eng) in Géotechnique > Vol. 62 N° 6 (Juin 2012) . - pp. 471 –478 Mots-clés : Sands  Failure  Numerical  modelling  Theoretical  analysis  Plasticity Résumé : This paper presents a criterion for detecting diffuse (homogeneous) instabilities in granular soils sheared under fully drained conditions. The criterion is based on bifurcation theory and applied to elasto-plasticity by allowing multiple incremental solutions in elasto-plastic soils, physically losing controllability of stress boundary conditions. Drained diffuse instabilities are poorly understood, and are induced by kinematic modes different from those observed in shear bands and liquefaction instabilities. Unlike shear bands, diffuse instabilities occur under fairly homogenous deformation modes and, unlike liquefaction, drained instabilities are not generated by the excess pore pressures. Recent experiments under drained constant shear report sudden homogeneous instabilities in samples of relatively dense and loose sands. The criterion presented in this paper is used in conjunction with an elasto-plasticity model for sands to predict and explain these reported drained instabilities. From a practical standpoint, these developments serve to expand the repertoire of potential instabilities that occur well before failure, and which have been reported in case studies of puzzling slope instability failures under fully drained conditions. DEWEY : 624.15 ISSN : 0016-8505 En ligne : http://www.icevirtuallibrary.com/content/article/10.1680/geot.10.P.109