Effect of Infill Moisture Content and Thickness on Shear Behavior of Rough Rock Joints

The shear behavior of rock joints have normally been investigated in the past by conducting conventional direct shear test in the laboratory, where during the shearing process, the effect of infill material is often neglected. It is well known that the shear strength of rock joints decreases significantly due to the presence of gauge on infill materials. In addition, the joint strength is highly dependent on the wear behavior of joint asperity during shear movement. Though many researches have been done about the influence of asperity on joint shear strength, however, only a limited number of studies are found in relation to the influences of infill thickness and water content on the shear strength of infilled rough joints. The current study is an attempt to investigate the shear behavior of soft rough joints under Constant Normal Load(CNL) conditions, with special reference to the influences of infill thickness and moisture content and wear behavior of joint asperity. The results of this study show that infill water content may influence shear strength of rough rock joints, as significantly as infill thickness.