MULTISCALE MODEL FOR DAMAGE-FLUID FLOW IN FRACTURED POROUS MEDIA

The paper deals with a closed-form continuum description of coupled fluid flow-deformation behavior of porous media with distributed strong discontinuities. Based on the underlying physics of the solid and fluid phases at the microscale, the macroscopic hydro-mechanical (HM) behavior of a representative elementary volume is eventually retrieved in the fully saturated case using the mean-field theory and Mori-Tanaka Homogenization Scheme. The heterogeneity that governs the overall HM behavior is induced by evolving microcracks described by a crack density distribution tensor. Herein, only the shape and orientation of microcracks are accounted for in the upscaling process. Examples are presented to assess the robustness of the proposed mathematical formulation. Finally, the evolution of heterogeneity in poromechanical parameters as well as hydraulic properties of the system is investigated by coupling a microcrack growth formulation under general loading conditions with fluid flow. We will briefly discuss, through material point simulations, how the proposed model can capture localized deformations and corresponding fluid transmission behavior starting from an initially homogeneous state.