This paper deals with the problem of the dissolution of soluble underground rocks and the geomechanical consequences such as subsidence, sinkholes and underground collapse. In this paper, the rock dissolution and the induced underground cavities aremodeled using a Diffuse Interface Model. We describe briefly the method. We used to perform the transition (upscaling) from a multiphysics problem formulated at the microscopic scale level (pore-scale) to the macroscopic scale level (Darcy-scale). Rock material considered in this paper is gypsum, despite that the developed method is also suitable for more soluble rocks. The mechanical consequences of dissolution are analyzed fortwo theoretical configurations, i.e., lens and pillar