Modelling of anisotropic sand behaviour

Abstract

This paper presents an extension of a previous model for isotropic granular soils, to account for both initial and stress-induced anisotropy. The proposed approach is based on Generalized Plasticity Theory, and introduces material micro-structure through a second order tensor, which is used to define a new set of “modified invariants”. Loading-unloading direction n and plastic modulus H are then related to micro-structure. Model predictions are checked against experimental data obtained on sand exhibiting structural anisotropy which is caused by a preferred orientation of grains along horizontal planes. This initial anisotropy is subsequently modified by loading.