Abstract
It is essential to understand the hydraulic behavior of rock apertures as the fluid flow path in the rock mass. The geometric parameters of fracture such as roughness of walls and fracture aperture have a significant effect on its hydromechanical behavior. In this paper, the laboratory tests are performed on the samples and then, the laboratory conditions are numerically simulated. The three-dimensional (3D) scanning of the walls of natural rock fractures is used to prepare the geometric model, and the ICEM CFD software is employed to prepare the geometry of fractures. Also, using the Ansys Fluent software and considering the Navier-Stokes equations in the model, the fluid flow in the rock fractures is simulated. Due to the fact that the two joint surfaces are in contact with each other, the model geometry is constructed in the case when the joints are mated and the contact is established in a certain percentage. In this way, the geometries are prepared for 15, 30, 45, 60, 75, and 90% contact between the upper and lower surfaces. The numerical modeling is also validated by the analytical Darcy formula, which indicates the accuracy of the modeling technique. The modeling results show that the macroscopic Forchheimer relation well describes the nonlinear fluid flow in the rock fracture. The values of linear and nonlinear coefficients of Forchheimer equation are estimated for each of the geometric models. The results show that the Forchheimer coefficients are directly related to the joint contact surface in an exponential manner, and the hydraulic aperture increases proportional to the reduced joint contact surface