Evaluation of the displacement discontinuity method on wave propagation through a thickly jointed rock mass

The displacement discontinuity method (DDM) has been commonly utilized to investigate the wave propagation in the jointed rock mass, in which the joint thickness is assumed to be infinitely thin. However, naturally filled joints are usually thick. To investigate the wave propagation through the thickly joint and evaluate the applicability of DDM in studying stress waves through the thickly joint, a study of stress waves across the filled joints with thickness was conducted. The wave transmissions through rock mass with different joint thicknesses and wave impedance ratios of the rock and joint were analyzed. The effects of the joint thickness and wave impedance ratio on wave transmission coefficient were discussed. Finally, the accuracy of DDM prediction was validated. The results show that the transmission coefficient decreases as joint thickness and wave impedance ratio increase. It is noted that the prediction accuracy of DDM is affected not only affected by joint thickness, but also highly affected by wave impedance ratio in front of and behind the joint. The prediction accuracy of DDM decreases as the joint thickness and wave impedance ratio increases. DDM studies the wave attenuation with high accuracy when the joint thickness and wave impedance ratio are small.