INFLUENCE OF CRACK DENSITY ON THE HYDRO-MECHANICAL BEHAVIOR OF A HORIZONTAL BOREHOLE UNDER ISOTROPIC COMPRESSIVE STRESS

Abstract

The excavation of boreholes induces a damage zone in the vicinity of the boreholes, and thereby affects the hydro-mechanical properties of the rock mass surrounding. This paper outlines analytical models of effective permeability and moduli of the porous rock containing a randomly crack distribution, which is an explicit function of the dimensionless crack density, crack conductivity, crack length and matrix permeability. These proposed models are then introduced into a finite element open source code, Code_Aster, to study hydro-mechanical responses of the medium around a horizontal borehole under isotropic far-field compressive stress for different cases of crack density. The results showed that the crack density changes the effective permeability and moduli and therefore under isotropic compressive stress it influences significantly the behavior of the borehole.