A hydrodynamic model for chemical dissolution of poroelastic materials

Geomaterials are multi-phase materials composed of solid skeletons and pore fluids. Along the solid-fluid interfaces, chemical dissolutions might occur which tends to weaken the strength of geomaterials and can potentially cause catastrophic failures. As the ionic species in the pore fluid evolve during dissolution, we introduce the mass fractions of all the ionic species as independent state variables into the hydrodynamic procedure and develop a mathematically rigorous and thermodynamically consistent modeling framework to address the impact of solid dissolutions on the constitutive properties of poroelastic geomaterials. The development is foundational in that it focuses only on saturated poroelastic systems without accounting for particle crushing, localized plasticity, and surface tensions. However, the theory can be further expanded to deal with such inelastic features under various saturation regimes. For simplicity, the density-dependent linear elasticity is adopted whereby the stiffness degrades as the solid skeleton dissolves and pore fluid pressure is governed by both osmolarity and compressibility. The developed model can naturally recover fluid-related dynamics of Darcy's law, Fick's law, and the law of chemical kinetics. Finally, experimental observations of debonding tests of calcarenite under both oedometric and unconfined conditions are used to validate the model performance.