Mechanical and Hydraulic Behaviors in a Single Fracture with Asperities Crushed during Shear

Abstract

Understanding the mechanical and hydraulic behaviors in a single fracture is important for underground rock engineering. In this study, coupled shear-flow tests were performed on five single fractures with regular dentate asperities, under different constant normal stresses and high inlet hydraulic pressures, to investigate the change of stress, displacement, and flow rate during shear. A new radial flow cubic law was established to estimate the hydraulic behavior, and a two-dimensional (2D) finite-element model, obtained by solving the Navier-Stokes equations, was used to analyze the discrepancy of the values between the new cubic law and experiments. Infilling materials had a strong influence in both mechanical and hydraulic behaviors. The discrepancy and em:eh ratio were influenced by recirculation zones, infilling materials, roughness, contact areas, and inertia force. The nonlinearity of fluid flow caused by inertia force had remarkable influence on hydraulic behavior with high hydraulic pressure. Increasing hydraulic pressure decreased hydraulic conductivity, the em:eh ratio, and discrepancy during the whole shear process.