大断面隧道三台阶七步开挖法仿真分析

Numerical simulation of the large cross-section tunnel excavation by 3-bench and 7-step method

结合实际工程,建立三维数值计算模型,对浅埋花岗岩地段隧道三台阶七步开挖法的施工过程进行了模拟计算。在此基础上,分析了地层的位移、支护结构变形和受力的变化规律以及分步开挖对支护结构受力和变形的影响。研究结果表明,洞周变形、支护结构的受力及变形具有不对称性;在支护结构距掌子面距离大于5~6m时,变形和受力可以达到稳定状态;边墙处锚杆的作用效果比拱顶锚杆显著;不同开挖步造成的洞周变形也有较大区别。分析结果可以为大断面隧道三台阶七步开挖法的设计和施工提供参考。

Based on the three-dimensional numerical calculation model, a tunnelling process of 3-bench 7-step excavation method of a project in shallow buried granite areas was simulated. According to the result, the change laws of the strata displacement, the deformation and force of supporting structure were analyzed. The impact on supporting structure deformation and force, coursed by step-by-step excavation, were analyzed too. The results show that the strength and deformation of the supporting structure are asymmetric ; the deformation and stress of the supporting structure can reach a steady state when the distance between tunnel face and supporting structure is greater than 5 - 6m ; the role of anchor in side wall is more important than that in vault; the deformation around the tunnel caused by the different excavation steps has a greater difference. The analysis results could be referred for the design and construction of large cross-section tunnel of 3-bench 7-step excavation.