A coupled elastoplastic damage model for sandstone considering chemical corrosion

摘要

Sandstone is a typical sedimentary rock. Chemical corrosion can accelerate the development of damage and reduce the strength of sandstone. An elastoplastic damage model considering the coupled chemo-mechanical damage is proposed to describe short-term mechanical behaviour of sandstone after immersing in the chemical solution. In the first part, the coupled damage variable is defined based on the analysis of chemical damage mechanism. In the second part, based on the framework of irreversible thermodynamics, the general formulation of the phenomenological model is presented. The model considers the effect of initial chemical damage on the evolution of mechanical damage. It can also describe the coupling between plastic deformation and mechanical damage. Meanwhile, a non-associated rule is chosen in order to describe the compression-dilatation transition of volumetric deformation. Comparisons between numerical simulations and experimental data show that the model is able to describe the main mechanical behaviour of sandstone under chemical corrosion.