动态原位监测技术在顺层岩体隧道的应用—以六汉隧道为工程实例

为明确六汉隧道浅埋顺层岩体开挖后围岩应力变化规律及特征。基于FLAC_^3D数值模拟分析顺层围岩隧道变形特性,对岩层节理面处偏压应力及二衬结构变形特征进行了施工期动态原位监测。结果表明：浅埋顺层岩体地形隧道开挖致使岩层节理面两侧局部应力不均衡,出现较大偏压应力和剪切应力；基于近9个月的监测点数据显示开挖20~30 m与80~90 m后,隧道初支与围岩接触应力变化明显,前者应力变化速率达到峰值,而后者开始趋于稳定；二衬混凝土结构应变随时间变化的响应规律表明初支结构承受围岩变形大部分有效荷载,二衬分担围岩变形传递的局部不均衡应力。其现场监测结果为今后该类型隧道设计与支护荷载的计算奠定了理论基础。

Application of Dynamic In-situ Monitoring Technology in Bedding Rock Mass Tunnel-Taking Liuhan Tunnel as an Example

To clarify the laws and characteristics of stress change of surrounding rock after excavation of shallow buried rock mass in the LiuHan Tunnel. Based on the FLAC_^3D numerical simulation analysis of deformation characteristics of bedding rock mass tunnels, dynamic in-situ monitoring was conducted on the unsymmetrical loading of rock mass of joint surface and the deformation characteristics of the second lining structure during the construction period. The results show that the shallow and bedding rock mass tunneling resulted in unbalanced local stresses on both sides of the rock joints surface, strong biasing stress and shear stress. Based on the data of the past 9 months showed that the contact stress between the SinitialSsupportingSof the tunnel and the surrounding rock obviousSchange, and the rate of stress change of the former was reached to the peak value, the latter began to stabilize after the excavation of 20~30 m and 80~90 m; the response laws of the strain of the second lining concrete structure changes withStime show that the primarySsupportSstructureS bears the most effective loading of the deformation of the surrounding rock, the second lining shares the local unsymmetrical loading caused by deformation of the surrounding rock. The on-site monitoring results lay a theoretical foundation for the calculation of the tunnel design and supporting loads in future.