Experimental and numerical modeling of shear behaviour of rock joints

The shear behaviour of soft rock joints is investigated in laboratory under both Constant Normal Load (CNL) and Constant Normal Stiffness (CNS) conditions. The laboratory behaviour is modelled numerically using the Universal Distinct Element Code (UDEC). The predicted shear stress, normal stress and dilation behaviour with shear displacements are compared with the laboratory results. It is observed that UDEC can predict the peak shear stress of unfilled joints under CNS, however, it overestimates the joint dilation as well as the normal stress. The maximum peak shear stress in UDEC is attained at a greater shear displacement in contrast to the laboratory observations. The UDEC predictions are generally in good agreement with the laboratory data under CNL condition, where the asperity degradation is found to be less significant.