Abstract: Take a karst tunnel in Yichang-Wanzhou railway as an example,by using the finite difference software FLAC3D the surrounding rock deformation of karst cave in the side of tunnel is simulated and compared with the field monitoring result. At the same time,a numerical analysis concerning the influence of the change of water pressure and distance between karst cave and tunnel is carried out. The results show that the horizontal displacement of lining structure near the karst cave is larger than that...