Finite element modelling of thermo-elasto-plastic multiphase porous materials

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. 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. Some cases of non-isothermal elasto-plastic consolidation of a soil column of Boom clay loaded by thermal, mechanical or environmental conditions are also studied. The coupled thermo-hydro-mechanical behaviour of the material caused by thermal and mechanical loads is analysed.