A hydrodynamic finite element model for chemo-mechanically loaded poroelastic materials

Porous geomaterials are exposed to intricate hydrochemical environments in nature. Consequential dissolution over long geological periods can degrade their mechanical properties. Rooted in a recently developed hydrodynamic formulation, this work develops a numerical model to clarify the chemo-hydro-mechanical processes involved, including coupled solute and solvent diffusions through pore fluid transients. Furthermore, a new implicit finite element solver is developed to capture the multi -physics, while special attention is given to consistent derivation and implementation. With this solver, simulations are performed to study the dissolution of porous calcarenites due to basal acid injection under oedometric conditions. The results demonstrate that the spatial distribution of the injected hydrogen ions tends to quickly reach a steady state due to reaction, while the dissolution -induced deformation accumulates steadily over time. This feature inspires a model simplification that combines the steady-state pH profile with nodal constitutive analysis to explore long-term deformations generated by solid dissolution. Compared to the comprehensive finite element analysis, this simplified approach is computationally efficient and robust. Both models show a good match with experimental data. Modeled results also highlight the importance of incorporating the coupled mass transports in the multicomponent flows, without which the model greatly underestimates the deformation.