Abstract: In light of the rock mass stability problem induced by a karst water burst during the construction of the Dayaoshan tunnel on the Wuhan-Guangzhou passenger dedicated line, and based on a FLAC3D numerical simula tion, this paper studies the influence of the karst cave on the rock mass stability and analyzes the filling and grouting schemes for the karst stratum that the tunnel passes through. The results show that: 1) the influence distance of the karst cave is 0~1 times the tunnel′s diameter, and the karst cave on one side of the sidewall has slight influence on the deformation of the other side of the sidewall; 2) there is a tensile failure zone in the rock stratum between the karst cave and the tunnel, with obvious stress and large deformation; 3) filling and grouting can improve the stress state of the surrounding rock and reduce the rock′s deformation and plastic range, and the optimum thickness of the radial grouting circle is 5 m.