Analysis of Coupled Thermohydromechanical Damage in Unsaturated Porous Media

In this study the theoretical framework of a thermohydromechanical damage model (THHMD model) for non-isothermal unsaturated porous media is presented. The framework of this model is based on the use of independent state variables (net stress, suction and thermal stress). The damage behavior law stems from phenomenological and micro-mechanical concepts. The stress-strain thermodynamic conjugation relations are derived from the free energy, which is written as the sum of damaged elastic deformation energies and of residual strain potentials. The damaged mechanical rigidities are computed by applying the Principal of Equivalent Elastic Energy (PEEE) for each stress state variable. The influence of damage on liquid water and vapor transfers is accounted for by introducing damage-induced intrinsic conductivities. In this paper after the review of the mentioned model, a parametric study is performed to assess the influence of the Excavated Damage Zone (EDZ) on the response of the nuclear waste repository during the heating phase. The trends meet the theoretical expectations..