A multiscale elastoplastic constitutive model for geomaterials with a porous matrix-inclusion microstructure

Abstract

Abstract A new macroscopic yield criterion is derived in the present work to describe the elastoplastic mechanical behavior of composite with a porous matrix-inclusion microstructure. The influences of porosity at the microscopic scale and the bigger inclusions at the mesoscopic scale are explicitly taken into account by this criterion. The solid phase at the microscopic scale obeys to a Drucker-Prager criterion for the dilatant effect. The exact solution can be retrieved in the special case of a porous medium having a Drucker-Prager type matrix. This improves fundamentally the one proposed in Shen et al. (2013) . This criterion is applied to describe the peak stresses of Callovo Oxfordian argillite obtained by the uniaxial and triaxial compression tests with different compositions and different confining pressures. Then, a complete constitutive model is established with a plastic hardening behavior and the non-associated plastic flow rule. The evolutions of the microstructure, such as the variations of the porosity and the volume fraction of inclusions with the loading process, can be fully considered by this micromechanics based model. By comparing the numerical results with the experimental data, the proposed model is able to capture the main features of the studied geomaterial with a porous matrix-inclusion microstructure.