A Simplified Model for Time-Dependent Deformation of Rock Joints

Understanding the time-dependent deformation behavior of rock joint is important when evaluating long-term stability of structures built on or in jointed rock masses. This study focuses on the time-dependent strength and deformation of unweathered clean rock joints. First, five grain-scale joint models are established based on Barton’s standard joint profiles using the GBM-TtoF creep material model. Barton’s non-linear shear strength criterion is adopted to determine the short-term shear strength of the joints. Second, a series of creep simulations are conducted to investigate major factors (normal stress, shear loading ratio, and joint roughness) that influence the long-term shear strength and the sliding velocity of the joints. The results reveal that normal stress has more influence than joint roughness on resisting creep slipping of the joints. Third, an equation for the prediction of creep sliding velocity is developed by fitting the simulation results and the equation is verified by experimental data. Finally, a creep slipping model for simplified flat joints is proposed, which can be used to model the long-term shear strength and sliding velocity of joints under creep deformation conditions. The creep slipping model, which can be used in both stationary and variable stress conditions, is useful for simulating time-dependent behaviors of jointed rock mass using the distinct element method.