基于超前支护加固的大断面深埋软弱围岩隧道快速施工方法研究

Research on the Rapid Construction Method of Large Section Deep Buried Tunnel with Soft Surrounding Rock based on Over-head Support Reinforcement

为研究软弱围岩大跨度公路隧道安全快速施工方法,以重庆陶家隧道为依托,建立三维数值计算模型,通过数值模拟与现场监测相结合的方法,分析了不同超前支护作用下分别采用三台阶法与弧形导坑法施工时隧道变形与受力变化情况,并选取了试验段进行验证。研究结果表明:采用超前支护后,隧道围岩稳定性得到了明显地提高,使用超前锚杆支护可以满足工程Ⅳ级围岩预加固需求;在充分地围岩预加固处治下进行隧道施工工法合理变更既可以保证施工的安全,还简化了工序,提高了施工效率;现场试验结果验证了该方法的安全性。

In order to study the safe and fast construction method of large-span highway tunnel with weak surrounding rock,based on Chongqing Taojia Tunnel,a three-dimensional numerical calculation model is established,and the deformation and force changes of the tunnel during the construction of the tunnel using the three-step method and the curved guiding pit method respectively under the effect of different over-above-support are analysed through the combination of numerical simulation and on-site monitoring,and the test sections are selected for verification.The results show that:the stability of tunnel peripheral rock is obviously improved after adopting the advanced support,and the use of advanced anchor rod support can meet the demand of IV peripheral rock pre-reinforcement of the project;the reasonable change of tunneling method under the treatment of sufficient pre-reinforcement of weak and weak peripheral rock can not only ensure the safety of tunneling,but also simplify the work procedures and improve the efficiency of the construction;and the results of the on-site test are similar to the results of the simulation.