Contact Phase-Field Modeling for Chemo-Mechanical Degradation Processes in Geomaterials: Focus on Pressure Solution Creep

The microstructural geometry of materials has a significant influence on their macroscopic response, all the more when the process is essentially microscopic as for microstructural degradation processes. However, the microstructural geometry tends to be overlooked and replaced by constitutive approximations. Contact phase-field modeling enables to both track the microstructural geometry's dynamics and include catalyzing/inhibiting effects, accelerating/delaying equilibrium, such as temperature or the presence of certain constituents like clay. To emphasize the influence of irregular microstructural geometries and catalyzing/inhibiting effects, we study numerically the chemo-mechanical response of digitalized geomaterials at the grain scale under pressure solution creep. We argue for accurately modeling the microstructural geometry in order to better capture the microscopic nature of pressure solution creep, consisting in transient interacting instabilities at the grain scale. The fitting of our numerical results to dynamic Andrade creep laws corroborates recent experimental results displaying such creep laws.