Abstract
The fluid flow mechanism in rock fracture is one of the basic elements in the coupled Thermal-HydraulicMechanical-Chemical (THMC) process, which is an important factor for underground rock engineering, especially for the safety assessment of radioactive waste repository. Fluid flow through a rock fracture is usually simplified as a parallel-plates model, which however, brings discrepancies against experimental and numerical simulation results in some contents, mainly due to the surface roughness of rock fracture and the inertial effect of fluid taking placing at high Reynolds numbers. JRC (Joint Roughness Coefficient) is one of the most extensively adapted parameter to quantify the surface roughness of rock fractures, however, the relation between mechanical aperture and hydraulic aperture of fractures developed based on JRC doesn't fit well with experimental and numerical simulation results. In this study, fluid flow through JRC profiles was simulated by solving Navier-Stokes equations, and the flow mechanism in fractures with different roughness was investigated. Based on the simulation results, an equation linking the relation between mechanical aperture and hydraulic aperture, with parameter Z2 which describes the geometrical characteristics of a rough surface and Reynolds number was established. This empirical equation takes into account both of the surface roughness and inertial effect, which can help estimate the fluid flow behavior of rock fractures in 2-D problems.
