Finite element simulation for rock salt with dilatancy boundary coupled to fluid permeation Original Research Article

This contribution is concerned with the long-term stress-induced deformation and the simultaneous fluid permeation of rock salt. To this end, a coupled finite-element strategy is presented, where the problem is formulated in the context of the theory of fluid-saturated porous media, considering two phases, i.e., the rock salt as a solid phase in which the remaining pores are filled with brine as a fluid phase. The constitutive model for the rock salt is based on true triaxial experimental tests thus taking into account a distinct boundary between the dilatancy and the compression domains in the octahedral stress space. For integration of this constitutive law, an implicit integration algorithm is presented. It is shown that the number of resulting equations can be reduced to two, irrespective of the dimension of the problem under investigation, and for solution of this set of equations a two-level strategy is presented. For illustrative purpose, the performance of the algorithm is demonstrated for a cylindrical specimen with two drillings loaded in compression and fluid pressure.