Multi-physics modelling of thermo-elasto-plastic saturated/unsaturated porous materials

This paper presents a formulation for the computational analysis of thermo-elasto-plastic multiphase porous materials based on Porous Media Mechanics, with the aim to simulate geo-environmental engineering problems analysed as multi-physics coupled problems. The numerical model is based on a fully coupled heat and multiphase flow model in deforming porous media. The porous medium is assumed to be a multiphase system where interstitial connected voids of the solid matrix may be filled with liquid water, water vapour and dry air. To handle this multiphase system, the general frame of averaging theories is used in deriving the governing equations. Phase changes of water (evaporation-condensation, adsorption-desorption) and heat transfer through conduction and convection, as well as latent heat transfer are considered. The elasto-plastic behaviour of the solid skeleton is assumed homogeneous and isotropic; the effective stress state is limited by the temperature and capillary pressure dependent ACMEG-Ts yield surface. The governing equations are discretized in space and time by means of the finite element method. The numerical examples will show applications of the full set of equations. In choosing the examples, validation of the model will be kept in mind. Validation of the implementation of the constitutive model is made by selected comparison between model simulation and experimental results for different combinations of thermo-hydro-mechanical loading paths. Coupled heat, water and gas flow in deforming porous media are validated against existing numerical solutions, e.g. [1]. The constitutive laws are validated against physical experiments in saturated and unsaturated conditions. Applications to the modelling of non-isothermal elasto-plastic consolidation at different partially saturated initial conditions or due to heating or desiccation are described.