硬岩地层中扁平大跨隧道拱盖法施工优化分析

Optimization Analysis of Flat Large-Span Tunnel Construction with Arch-Cover Method in Hard Rock Stratum

以青岛地铁1号线人民广场站—衡山路站区间站前折返线为例,采用三维数值模拟方法分析了初期支护拱盖法分步开挖过程中地面沉降、拱顶沉降、初期支护受力和围岩应变的变化规律,进一步分析硬岩地层中扁平大跨隧道施工二次衬砌拱盖法优化为初期支护拱盖法的可行性,并通过现场监测结果加以验证。研究结果表明:硬岩地层中扁平大跨隧道采用初期支护拱盖法施工地面沉降、拱顶沉降、初期支护和围岩的应变满足规范要求,二次初砌拱盖法优化为初期支护拱盖法切实可行;拆撑是初期支护拱盖法开挖工序中的重要阶段,确定合理的拆撑长度是该工法成功应用的关键。

Taking People s Square Station Hengshan Road Station of Qingdao Metro Line 1 as an example the variation laws of ground settlement vault settlement primary support force and surrounding rock strain of primary support arch cover method during step by step excavation process were analyzed by using three dimensional numerical simulation method.The feasibility of primary supports arch cover method optimizing from secondary lining arch cover method in the flat large span tunnel construction in hard rock stratum was further analyzed and verified by the field monitoring results.The research results show that in hard rock stratum the ground settlement vault settlement primary support and strain of surrounding rock of flat large span tunnel constructed by primary support arch cover method should meet the requirements of the code it is feasible to optimize the secondary lining arch cover method to the primary support arch cover method.Bracing removal is an important stage in the excavation process with the primary support arch cover method and the key to the successful application of this method is to determine the reasonable length of the bracing removal.