GENERALIZED EFFECTIVE STRESS LAW FOR MULTI-POROSITY MEDIA UNSATURATED WITH MULTIPHASE FLUIDS

The effective stress law for porous media is widely employed in the analysis of fluid-solid coupling problems. This paper proposed a generalized effective stress law for multi-porosity media unsaturated with multiphase fluids, considering the porosity multiplicity, phase numbers of porous fluids, anisotropy, saturation degree, and metric suction. Under the hypothesis that the solid and liquid phases both only undergo liner elastic deformations, the effective stress law for the anisotropic multi-porous media unsaturated with multi-phase liquid (without the consideration of matric suction) was proposed by the approaches of stress separation and superposition of boundary conditions. The solid's linear elastic deformation and the deformation induced by the matric suction occurring on phase interfaces in an unsaturated porous media were contemplated to attain a generalized form of the effective stress law for unsaturated porous media. Most of expression formats of the effective stress laws in literatures can be obtained from corresponding reduced forms of the generalized law proposed, which proves its reasonableness.