Finite Element Analysis of Strain Localization in Natural Clay Using Elasto-Viscoplastic Constitutive Model

Abstract

AbstractIn geotechnical engineering, strain localization and the formation of shear bands is regarded as initiator of failure as a result of non-uniform deformations within soil, making clear understanding of strain localization very important to geotechnical engineers dealing with slope stability. In this paper strain localization in natural clay is studied numerically using finite element method (FEM). A new elasto-viscoplastic constitutive model that is implemented into ABAQUS with the ability to accurately describe the time-dependent, over-consolidated and structural characteristics of natural soft clay is used to perform 2D plane strain compression test under undrained conditions on undisturbed Kyuhoji marine clay. The influence of confining pressure and strain rate on strain localization is studied by numerically analyzing their effects on the formation and evolution of shear bands, thickness as well as the orientation of shear bands in natural clay. The results show that four crossing shear bands are observed in which higher confining pressure results in thinner shear band and a slightly smaller shear band angle as compared to lower confining pressure. An increase in strain rate increases the shear band angle and shear band thickness. Mesh dependency is not very apparent on the mechanical response of the specimen but affects the shear band features.