Anisotropic bounding surface plasticity with rotational hardening for unsaturated frictional materials

Abstract
A constitutive model for inelastic mechanical behaviour of inherently anisotropic soils is presented. An existing single surface model with isotropic hardening for empty and saturated cohesionlessoils [1] and general bounding surface plasticity [2-3] form the basic framework to which rotational hardening is added. The concept of state parameter [4] is used to predict the response of soil to different densities, drainage and stress paths. Unsaturated behaviour is described using net stress and suction as independent stress variables and modifying the basic constitutive surface parameters and hardening rules to consider the role of suction.