高地应力软岩隧道圆形断面扩挖施工围岩及支护受力特征研究

发布时间：2018-11-16 17:53

【摘要】：针对高地应力软岩隧道开挖时围岩大变形问题,以某隧道圆形扩挖段为背景,采用三台阶法施工和3层初期支护+小导管注浆+二次衬砌的复合结构支护,并通过现场监测、数值模拟和理论计算研究开挖过程中的围岩变形及支护结构受力。结果表明:上、中台阶开挖时的隧道围岩变形速率较大,在仰拱封闭和第3层初期支护施作完成后,隧道变形趋于稳定;采用3层初期支护结构可有效改善隧道周边围岩应力,3层初期支护基本都是受压结构,拱腰和边墙处竖向应力最大,拱顶处水平应力最大;二次衬砌拱腰、拱顶、拱脚和边墙处安全系数均大于规范要求,保证隧道结构安全。
[Abstract]:In view of the problem of large deformation of surrounding rock during excavation of soft rock tunnel with high ground stress, taking the circular expanded excavation section of a tunnel as the background, the composite structure supporting with three step method and three layer initial supporting small pipe grouting secondary lining is adopted, and the monitoring is carried out on the spot. Numerical simulation and theoretical calculation are used to study the deformation of surrounding rock and the force of supporting structure during excavation. The results show that the deformation rate of the surrounding rock of the tunnel is larger when the middle step is excavated, and the tunnel deformation tends to be stable after the closure of the inverted arch and the completion of the initial support of the third layer. The stress of surrounding rock around the tunnel can be effectively improved by adopting the three-story initial supporting structure. The initial support of three stories is basically compressed structure, the vertical stress at the arch waist and the side wall is the largest, and the horizontal stress at the arch top is the largest. The safety factor of the secondary lining arch waist, arch top, arch foot and side wall is higher than that required by the code, which ensures the tunnel structure safety.
【作者单位】：中铁隧道勘测设计研究院;中铁隧道集团有限公司;北京交通大学土木建筑工程学院;
【分类号】：U455.4

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