The Onset of Strain Localization in Cross-Anisotropic Soils Under True Triaxial Condition

Abstract

ABSTRACT The influences of inherent cross-anisotropy on soil strength on the homogeneous deformation and bifurcation characteristic of the stress-strain relationship are studied. By neglecting the cohesion term and employing an elliptical shape function in Mohr-Coulomb failure criterion, a 3D anisotropic failure criterion is proposed to describe the strength of cross-anisotropic sands under true triaxial conditions. Based on the proposed failure criterion, the influence of the anisotropic parameter on the failure curve on the deviatoric plane and the relationship between the peak friction angle and the intermediate principal stress ratio are obtained. The suitability of the criterion is justified by comparing with a series of true triaxial tests on sands without strain localization. The proposed failure criterion is adopted to build a three dimensional anisotropic elasto-plastic model, which allows the bifurcation analysis to be incorporated with the non-coaxial flow rule for the purpose of studying the onset of strain localization. Compared with the true triaxial tests under several intermediate principal stress ratios conditions in the literature, the proposed model and bifurcation analysis is shown to be capable of predicting the influence of inherent cross-anisotropy on the onset of strain localization.