STABILITY ANALYSIS OF XIANGLUSHAN TUNNEL SURROUNDING ROCK IN CONSIDERATION OF FLUID-STRUCTURE COUPLING

In this paper, a tunnel excavation support model was established according to the actual surrounding rock support and water bearing condition of Xinglushan tunnel. Considering the influence of water pressure and initial support, the convergence displacement of the tunnel in IV-grade surrounding rock, V-grade surrounding rock and the water-rich area of the V-grade surrounding rock were simulated and compared with the final displacement data of the field monitoring. The analysis results verify the accuracy of the simulation method. Then, the influence of surrounding rock water pressure, buried depth, lateral pressure coefficient and excavation method on the final convergence displacement of tunnel were analyzed. The results show that the final convergence displacement of the tunnel begins to linearly increase with the increase of water pressure, and then the increase rate increases until the tunnel becomes unstable and fails. With the increase of tunnel depth, the final convergence displacement in vertical and horizontal directions increases linearly. With the increase of the lateral pressure coefficient of surrounding rock, the final convergence displacement of the tunnel in the horizontal direction increases linearly, while the final convergence displacement in the vertical direction decreases slightly. Compared with the step excavation method, the center diaphragm method and ring cut method have better control effect on the convergence displacement of the tunnel.