A new constitutive model of unsaturated soils using bounding surface plasticity (BSP) and a non-associative flow rule

Abstract

This paper presents a constitutive model for unsaturated soils, based on the non-associate bounding surface plasticity concept under a critical state framework. With a limited number of parameters, this model allows removing the sudden stiffness reduction at the on-set of plastic strains when the stress reaches the yield surface. It also enables to reproduce smooth transitions from pre-peak hardening to post-peak softening and from contractant to dilatant behavior, which are common short comings of more classic models. The performance of this model is highlighted by a comparison between its numerical results, those from other unsaturated elastic–plastic models and experimental data.