Bifurcation analysis of shear band in sand under true triaxial conditions with hypoplasticity

Abstract

Predicting the onset of shear band is of significance in understanding the failure of geomaterials. The prediction accuracy is dictated by the constitutive model used for the description of the pre-bifurcation behaviour. In this study, we first modify a recently proposed hypoplastic constitutive model by incorporating a general strength criterion and a stiffness function. We proceed to consider the onset of shear band in sand under true triaxial conditions. We demonstrate that our analyses capture the pre-bifurcation stress–strain relationship at different values of intermediate principal stress and predict fairly well the onset of shear band. The acoustic tensor criterion generally adopted in elastoplastic approaches is inadequate for hypoplastic approaches. No special non-coaxial treatment is required for the present approach to yield a reasonable variation trend of bifurcation strain with intermediate principal stress ratio (Formula presented.).