A model for stress and plastic strain induced nonlinear, hyperelastic anisotropy in soils

The experimental evidence that cohesive and granular soils possess an elastic range in which the elasticity is both nonlinear and anisotropic-with stiffness and directional characteristics strongly dependent on stress and plastic strain (the so-called 'stress history')-is given a formulation based on hyperelasticity. This is accomplished within the framework of elastoplastic coupling, through a new proposal of elastic potentials and a combined use of a plastic-strain-dependent fabric tensor and nonlinear elasticity. When used within a simple elastoplastic framework, the proposed model is shown to yield very accurate simulations of the evolution of elastic properties front initial directional stiffening to final isotropic degradation. Within the proposed constitutive framework, it is shown that predictions of shear band formation and evolution become closer to the existing experimental results, when compared to modelling in which elasticity does not evolve. Copyright (C) 2007 John Wiley & Sons, Ltd.