关键词: 串珠状溶洞, 数值模拟, 岩溶处理, 稳定性分析

Abstract: This paper presents a case history of Bangshan Tunnel of the Xiarong highway capacity expansion project. The engineering geological conditions and the hydrological characteristics in the tunnel site area are investigated and evaluated. The numerical simulation methods are used to analyze the impact of the hidden continuous karst cavities on the stability of the tunnel surrounding rock mass. The locations, developments and the fill material of the karst rock cavities are evaluated. The following results are obtained: 1) When bead shaped karst rock cavities develop at the top of the tunnel, the deformation of the tunnel surrounding rock mass is large, but the impact on the deformation of the arch crown and the arch waist surrounding rock is different. At the same time, under the influence of the excavation disturbance stress, the surrounding rock mass and the support stress near the karst cavities significantly increase. The stress concentration occurs at the arch crown and the arch waist. 2) Research and practice have shown that the proposed karst rock cavity mitigation plan is reasonable and feasible, which ensures the safe and smooth construction through the karst section of the tunnel. The relevant results can provide a good guidance and reference for the design and construction of tunnels in the karst areas.

Key words: Bead Shaped Karst Cavities, Numerical Simulation, Karst Treatment, Stability Analysis