Numerical Implementation of Extended Macari, Runesson, Sture, Lade (MRS-Lade) Model for Unsaturated Soil for Finite Strain

Abstract

Mechanical behaviour of geomaterials have high complexity and variability, witch have been reported a large number of constitutive models, depending on different mathematical
idealizations.
The pressure dependent elasto-plastic models are considered as the most appropriate representations this behaviour because of the existence of inelastic deformation of the materials subjected to shear stress or/and volumetric pressure. Because the mathematical complexities this models, such as nonlinear elastic law and work plastic dissipation dependent hardening/softening law, resulting from
the complex nature implementation is not trivial.
This paper present an elastic-plastic model for unsaturated soils within the regime of finite deformation based in an extension of model’s of Macari, Runesson and Sture originally devised by Lade et al. (MRS-Lade). An overall implicit return method for non-associative elastic-plastic model of geomaterials is presented within the regime of large strains. The mathematical model formulated in the framework of additive elastic-plastic decomposition of the rate deformation tensor is briefly summarized. Representative numerical simulation was performed under axial symmetric compression
conditions and the results of the simulations are discussed to assess the performance of the unsaturated soils model.