Abstract：Deformation and strength characteristics of fractured rock masses are always the focus in geotechnical engineering. The key for determining deformation modulus and strength parameters is to study representative elementary volume(REV) and scale effects of fractured rock mass. Based on field investigations of fracture distribution in rock mass of Jinping II Hydropower Station，fracture network and meshes considering zero- thickness fractures for numerical simulation are generated. Mechanical models of rock and fractures are established separately based on laboratory triaxial and shear test results. Scale effects，REV and anisotropic properties of rock mass are studied by FEM considering different scales and orientations in site. The achievements will benefit parameter determination in Jinping II Hydropower Station；and the method can offer important reference for other practical engineering.
