Coupled hydromechanical modeling of rock fractures under normal stress

Abstract

In this paper, a nonlinear poromechanical model is developed for a single rock fracture under normal stress. The fracture is represented by a set of voids, and the progressive fracture displacement is considered as a modification process of void space. Based on experimental data obtained from three representative rock fractures, the constitutive model is formulated through an extension of Biot poroelasticity theory to a saturated fracture. A generalized poroelastic coupling coefficient is introduced to describe the interaction between pore fluid pressure and fracture deformation. This coefficient is expressed as a function of fracture aperture. Five parameters involved in the model have been determined from mechanical and poromechanical compression tests. The validity of the model is checked on fluid flow tests under different normal stresses. Comparisons between numerical simulations and experimental data are provided.Key words: hydromechanical coupling, interfaces, joints, poroelasticity, rock mechanics, fractures.