Continuous Karst Cavity Treatment and Surrounding Rock Stability Analysis of Bangshan Tunnel in Xiamen-Chengdu Expressway
This paper presents a case history of Bangshan Tunnel of the Xiarong highway capacity expansion project.The engi-neering geological conditions and the hydrological characteristics in the tunnel site area are investigated and evaluated.The nu-merical 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 dif-ferent.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.
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