Enhanced THM coupling for anisotropic geomaterials and smoothed-FEM simulation
International Journal of Mechanical Sciences, 290:110087, 2025.
X.-H. Wu and Q. Zhang contributed equally to this work.
As the thermo-hydro-mechanical (THM) coupling phenomenon becomes more and more common in various engineering applications, a deeper understanding of the behavior of the porous media under combined “THM loading” would be extremely useful. As researchers in computational geomechanics, we first revisit the established poromechanics theory and then move one step forward to (1) derive a generalized fluid flow equation that incorporates both mechanical and thermal strain anisotropy; and to (2) propose an analogous poro-elasto-plastic structural heating/cooling term that bridges not only to the phenomenological porothermoelasticity but also to the uncoupled standard thermal equation. Next in the section of the numerical method, we enrich the stabilized node-based smoothed finite element method (SNS-FEM) to incorporate THM coupling, which leads to the development of smoothed nodal thermal strain and smoothed thermal strain gradient. Subsequently, the proposed numerical framework is verified against three benchmark tests, which aim for the correct implementation of heat convection and THM contact, as well as the comparison with FEM. Finally, two hypothetical model application examples are presented, which investigate the effect of mechanical anisotropy and cross-coupling in THM biaxial test and the effect of temperature in pipeline penetration, respectively. Overall, this study offers a promising contribution to the understanding and modeling of THM problems.