Numerical study of a thermo-hydro-mechanical damage model for unsaturated porous media
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The “THHMD” damage model presented in this article is dedicated to non-isothermal unsaturated porous media. The proposed frame is based on the use of independent state variables (net stress, suction and thermal stress). Stress/strain relations are derived from a postulated expression of the free energy, accounting for the existence of residual strains. The damaged mechanical rigidities are computed by applying the Principle of Equivalent Elastic Energy for each stress state variable. The influence of damage on liquid water and vapor transfers is accounted for by introducing internal length parameters, related to specific damage-induced intrinsic conductivities. The “THHMD” model has been implemented in Θ -Stock Finite Element code. The mechanical aspects of the model have been validated by comparing the numerical results with experimental reference data. A nuclear waste repository model has been reproduced. The elastic predictions are in satisfactory agreement with the reference results. The parametric studies performed on damage parameters meet the theoretical expectations. Damage gets higher with higher damage rigidities. Water permeability grows with damage and with the internal length parameter.