Saturated Elasto-Plastic Porous Media under Consideration of Gaseous and Liquid Phase Transitions

Summary

Taking a closer look on, e.g., storage processes of greenhouse gases in deep geological aquifers or pressure changes in shear bands, the observation can be made that pressure and temperature changes in porous materials can induce phase transition processes of the respective pore fluids. For a numerical simulation of this behaviour, a continuum mechanical model based on a multiphasic formulation embedded in the well-founded framework of the Theory of Porous Media (TPM) is presented in this contribution. The single phases are an elasto-viscoplastic solid skeleton, a compressible pore gas consisting of the components air and gaseous pore water (water vapour) and an incompressible pore liquid, i.e., liquid pore water. The numerical treatment is based on the weak formulations of the governing equations, whereas the primary variables are the common temperature of the overall medium, the displacement of the solid skeleton and the effective pressures of the pore fluids. An initial boundary-value problem is discussed in detail, where the resulting system of strongly coupled differential-algebraic equations is solved by the FE tool "PANDAS".