Characteristics of poroelastic deformation and dissipation of heat and pore pressure in fluid-saturated porous strata

Abstract

Although there has been extensive research on the coupling process, some unexplored issues still deserve deeper exploration. In this study, our focus is on analysing the characteristics of poroelastic deformation and dissipation in thermal-hydraulic-mechanical (THM) coupling in fluid-saturated porous media. First, a coupled THM model is established as an extension of our previous study, where a solution strategy is presented based on the finite Fourier transform. The formulation is a unified framework that is compatible with the existing methods, and can be naturally decoupled into the simpler HM or TM version. Then, it is verified by benchmark study. The coupling behaviours of four different geomaterials (clay, salt rock, granite and marble) are analysed and compared in detail. We focus on several aspects: (1) dominance of hydraulic and thermal effects in different geomaterials; (2) evolution of pore pressure and heat dissipation; (3) effect of geomaterial properties on poroelastic deformation; (4) characteristics of drainage effect, cooling effect and expansion relaxation. It demonstrates that the proposed model is competent to capturing the essentials in coupling process. The insights gained from the simulations are intuitive and consistent with the existing knowledge. Further study and dimensional analysis reveal that the mechanisms in the coupling process are attributed to the combined effects of the temporal evolution in poroelastic deformation and dissipation.