Constitutive modeling of residual soils based on irreversible strains decomposition

Abstract

A constitutive model is proposed for describing the stress-strain behavior of saturated residual soils based on experimental observations from oedometer testing, triaxial and direct shear testing. The model is formulated within the classical theory of plasticity with a non-associated flow rule. In order to reproduce particular features of residual soils, inelastic strains are decomposed in two components, namely the plastic dilation due to the rearrangement of grains and the volumetric collapse resulting from bonds degradation. The yield surface is tear-drop shaped and obeys an isotropic volumetric strain-hardening rule related to collapse strains, along with a shear softening with developing plastic deviatoric strains. Comparison with published experimental data confirms the capability of the model of reproducing observed behavior of tropical residual soils in consolidated drained and undrained triaxial compression.