Study on crack coalescence process under loading and hydraulic pressures

Abstract

The coupling action of seepage and fracture on crack coalescence process under loading and hydraulic pressures are investigated. Numerical results demonstrate that the trend and magnitude of the permeability variations are controlled by the stress and the damage evolution developed in rocks. This includes the induced stress evolution of flow properties, and the regions of both diminished and enhanced flow depending on which the rock is in the linear-elastic, nonlinear, or post-failure portions of the stress-strain curves are presented. In elastic deformation region, rock permeability reduces when the rock compacts, and the decrease rate of the permeability starts to slow down or gradually to increase again when micro fractures begin to nucleate. Dramatic permeability increase occurs as soon as the macro-fracture forms in the rock.