A 3-D mixed thermo-hydro-mechanical model of soil consolidation

In realistic consolidation problems with complex 3D heterogeneous domains the efficient and accurate solution to the coupled system of the PDEs governing the mass and the energy balance in a deformable porous medium requires the use of advanced numerical algorithms. In the present communication a novel coupled 3-D numerical model based on an appropriate combination of Finite Elements (FEs), Mixed FEs (MFEs), and Finite Volumes (FVs) is developed with the aim at stabilizing the numerical solution. Elemental pressures and temperatures, nodal displacements and face normal Darcy and Fourier fluxes are used as primary variables. This leads to an element-wise conservative velocity field with the same order of approximation for both pore pressure and stress, and allows for the accurate prediction of sharp temperature convective fronts. A staggered technique is employed for the solution of the globally coupled thermo-hydro-mechanical model, where flow-deformation and heat transport are addressed iteratively by MFEs and FEs and by MFEs and FVs, respectively, at each time step. The model is successfully tested in two large size realistic and numerically challenging applications.