Constitutive Modeling of a Suffusive Soil with Porosity-Dependent Plasticity

Abstract

Seepage flow through a deformable porous medium may cause detachment, transport, and even deposition of fines particles which are initially parts of the granular skeleton. This volumetric erosive process is called suffusion. With the aim of modelling the mechanical consequences of suffusion, we propose a constitutive framework for a fully coupled poromechanical model of a suffusive soil. Considering kinematics, suffusion is modeled as a mass transfer from the solid phase to the fluid phase. We therefore introduce, into the classical poromechanical framework, a new state variable $\phi _{er}$ as the suffusion induced porosity. From thermodynamics of porous media, we deduce a possible coupling between suffusion and seepage flow. In order to capture the mechanical consequences of suffusion, $\phi _{er}$ is also regarded as an internal variable into a poroplastic model so that it contributes to the hardening rule. Numerical integrations of the developed model were carried out under monotonic drained loading conditions in such a way that a part of the abilities of the model are illustrated.