Relationship between surface fractal characteristic and hydro-mechanical behaviour of rock joints

In this paper, the direct shear experiments of rock joint have been carried out based on a new direct shear-flow test apparatus which accommodates the change in normal stress with dilation under the constant normal stiffness (CNS) boundary condition. By using a new laboratory visualization system, the high quality flowing image through the rock joint is investigated. A three-dimensional fractal measurement method which can estimate the real fractal dimension D-s epsilon [2, 3] for a rock joint surface has also been introduced. Furthermore, the coupled mechanical and hydraulic properties of rock joints under CNL (constant normal load) and CNS boundary conditions are discussed to increase the knowledge and understanding of hydromechanical feature of rock joints.