Elastoplastic Damage Modeling in Unsaturated Rocks and Applications

Abstract

This paper is devoted to coupled hydromechanical modeling of an underground cavity subjected to excavation, drying, and resaturation. An elastoplastic damage model is proposed for the description of poromechanical behavior of semiductile rocks in saturated and unsaturated conditions. The poroelastic behavior of material is nonlinear and dependent on water saturation degree. The plastic deformation is described using a curved yield surface and a nonassociated flow rule, in order to describe the pressure sensitivity and transition from volumetric compressibility to dilatancy. The evolution of material damage is related to tensile plastic strains. The coupling between plastic deformation and damage is taken into account. The capillary effects on plastic deformation are considered through a generalized effective stress concept. The proposed model is implemented in a finite element code for fully coupled thermohydromechanical problems. An example of application is presented for a cavity subjected to excavation drying and resaturation. The evolutions of plastic and damaged zone, and saturation degree around the cavity are studied.