ABSTRACT
The presence of joints in the rock mass plays an important role on the overall shear and deformability behaviour of the rock, as well as in-situ stress and hydrogeological conditions. The jointed rock mass strength is considerably smaller than the intact rock mass strength. The choice of the correct shear strength parameters becomes more difficult for joints in hard rock filled with weak or loose material. The thickness of the infill material may vary from a fraction of a micron to several millimeters. The drainage condition is one of the important factors during shearing that also controls the shear behaviour of infilled joints. The stiffness of the fill under shear can affect the strength of the joint because of the problems dealing with two materials with different mechanical properties. The difference in stiffness between the rock and the infill facilitates progressive failure.
