Experimental study on permeability response in fractured rock to the effect of hydro-mechanical coupling, fracture geometry, and component content

The conductivity of fractured rock mass caused by the hydro-mechanical behavior and attributes of the rock is critical for fluid seepage and solute diffusion. To study the evolution of fluid conductivity in fractured rock mass, by considering the hydro-mechanical coupling effect, fracture geometry, and component content, triaxial coupling and water-adsorption experiments were conducted. The results show that an increase in permeability is positively related to hydraulic pressure and negatively related to confining and axial stress. The conductivity of fractured rock mass is closely related to fracture morphology and component content. Compared with the dynamic hydraulic pressure dependence of permeability for dual-fracture sandstone, a dynamic confining stress dependence and history memory effect of permeability was observed in single-fracture sandstone, whereas the dynamic confining stress dependence of permeability for single-fracture sandy mudstone was observed, and dynamic hydraulic pressure dependence and history memory effect permeability for multi-fracture sandy mudstone and intact sandy mudstone was presented. Furthermore, the permeability of single-fracture sandy mudstone is two orders of magnitude more than that of multi-fracture and intact sandy mudstone. The integrated effect of hydro-mechanical coupling, fracture morphology, and component content on the conductivity is characterized by confining stress-dependent history memory indexes of 0.04e-17, 0.125e-19, and 0.2e-19 for single-fracture, multi-fracture, and intact sandy mudstone, respectively.