隧道顶部隐伏串珠状岩溶处理及围岩稳定性分析

Continuous Karst Cavity Treatment and Surrounding Rock Stability Analysis of Bangshan Tunnel in Xiamen-Chengdu Expressway

以厦蓉高速公路扩建工程邦山隧道为依托,在隧址区工程地质条件和水文特征调查分析基础上,采用数值模拟方法,分析顶部隐伏串珠状溶洞对隧道围岩稳定性影响规律,在此基础上针对岩溶位置、发育规模、充填物性状等,制定了相应的处置措施,研究表明:(1)隧道顶部串珠状岩溶发育时,隧道围岩整体变形较大,但对拱顶与拱腰围岩变形影响各不相同。在开挖扰动应力影响下,溶洞附近围岩与支护应力明显增大,且在拱顶、拱腰出现应力集中。(2)实践证明所提出的岩溶处置方案合理可行,保障了隧道岩溶段的安全顺利贯通。相关研究成果可为岩溶区隧道设计与施工提供一定的指导借鉴作用。

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.