Abstract:The stress and seepage properties are mainly decided by the geometry such as surface roughness and aperture of rock joints;meanwhile,the different boundary conditions such as initial normal stress and normal stiffness also affect the stress and seepage properties. By using GIS technique,a new geometrical model is developed to describe the surface roughness and the aperture of a rock joint quantitatively. Numerical programs for simulating shear process are coded based on mechanical and hydraulic models of a rock joint;and then,the stress and seepage properties during the shearing processes are simulated and predicted by using GIS technique. The main results of this research show that during shear process,the normal stress,aperture of fracture and hydraulic conductivity increase gradually and reach to stable values at last under different boundary conditions as the shear displacement increases. The hydraulic conductivity increases with two orders. However,the shear stress leaps to a peak one at the first step and decreases quickly at the second step. And then,the shear stress under constant normal stress reaches a stable value soon,while the shear stress under constant normal stiffness increases slowly.