Abstract:Based on case of the colliery No.3 of Huainan coalfield in Anhui Province,the relations of sonic velocity and mechanical characteristics of the lithofacies transition rock mass are investigated by the physical modeling study and numerical simulation technique. It is found that the stress and sonic velocity are controlled by the lithofacies and its thickness. During mining processes,the existence of lithofacies transitions in rock mass changes the stress distribution of the roof in the mining faces as follows:(1) the top of lithofacies transition body is artesian flow areas;and (2) the port is located in the stress concentration position. Meanwhile,it shows that the lithofacies transition body influences the sonic velocity of the propagation in the rock mass. Upon the body,the sonic velocity propagating in the rock mass is greater than that in the below. Usually,when the sonic wave passes through the phase transition body,the sonic velocity changes to the lower,which can be used to interpret the detections some geological circumstances in the underground works and seismic exploration.