Caves have a significant impact on the stability of tunnels,and timely support can ensure the con-struction safety of karst tunnels.Taking the Bihuashan Tunnel as an example,a numerical simulation method is used to establish an analysis model of the karst tunnel.The relative position and size of the cave are the main influencing factors,including the net distance and circumferential position between the cave and the tun-nel,as well as the diameter of the cave,and their effects on the displacement of the surrounding rock of the tunnel are analyzed.Through the displacement of the surrounding rock and the zone state index ZSI,com-bined with the convergence-constraint method,the timing of the support of the karst tunnel is comprehensive-ly judged.The results show that the circumferential position of the cave has a greater influence on the stability of the tunnel compared to the net distance and diameter of the cave.Due to the influence of the cave,the dis-placement development law at different positions of the surrounding rock is not the same,so it is difficult to judge whether the tunnel has entered an elastic-plastic state based on a certain displacement characteristic.However,the ZSI can more intuitively display the status of the karst tunnel,providing assistance in determi-ning the timing of the support of the karst tunnel.
karst tunnelconvergence-constraint methodzone state indexsupport timingFLAC3D software
NETL
NSTL
万方数据
