A model for non-isothermal variably saturated porous media in dynamics

This work presents the development of a fully coupled mathematical and numerical model for the analysis of the thermo-hydro-mechanical behaviour of non-isothermal multiphase porous materials in dynamics. The model is developed following Lewis and Schrefler within the Hybrid Mixture theory [1]. The porous medium is treated as a multiphase system composed of a solid skeleton with open pores, filled with liquid water and gas. The solid is considered as deformable and non-polar. All the fluids are in contact with the solid phase. The constituents are assumed to be isotropic, homogeneous, immiscible, except for dry air and water vapour and chemically non-reacting. Local thermal equilibrium between the solid matrix, gas and liquid phases is assumed. Heat conduction, vapour diffusion, heat convection, liquid water flow due to pressure gradients or capillary effects and water phase change (evaporation and condensation) inside pores are all taken into account. In the partially saturated zones, liquid water is separated from its vapour by a meniscus concave toward gas (capillary water). In order to analyse the thermo-hydro-mechanical behaviour of a soil structure in the low frequency domain, e.g. under earthquake excitation, the u-p formulation is advocated for the finite element discretization.