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大断面浅埋偏压隧道洞口段施工困难,风险高;且受洞口复杂地质条件和施工空间效应影响,隧道支护结构变形和受力特性复杂,施工控制难度高。针对在建的宝兰客专小墁坪隧道出口浅埋偏压段的施工稳定性问题,采用数值模拟试验分析方法,研究了三台阶+临时横撑施工中不同上、中、下台阶错开距离时隧道的施工动态特性,分析了不同错开距离时隧道支护结构的变形和受力特点;基于数值模拟试验确定了大断面偏压隧道洞口段的施工方案,跟踪隧道施工进行的变形监测验证了推荐的三台阶+临时横撑施工中上台阶与中台阶错开5 m,中台阶与下台阶错开10~15 m(即1倍洞径)距离的施工参数经济、合理、可行,保证了隧道施工的安全,也为同类隧道工程的建设提供有益的借鉴和指导。
Due to the complicated geological conditions and the space effect of construction, the deformation and stress characteristics of the tunnel supporting structure are complex and the construction control is difficult to control. In view of the construction stability of the shallow bias section at Xiaolangping tunnel exit in Baolan Passenger Dedicated Area under construction, numerical simulation test and analysis method were used to study the different staggered distances of the upper, middle and lower steps The dynamic characteristics of tunnel construction are analyzed. The deformation and stress characteristics of tunnel supporting structure with different staggered distances are analyzed. Based on the numerical simulation test, the construction scheme of tunnel entrance section with large cross-section is confirmed, and the deformation monitoring of tunnel construction is verified The recommended three steps + temporary support during the construction of the stairs and the stairs staggered 5 m, the stairs and the next step staggered 10 ~ 15 m (ie 1 hole diameter) of the construction parameters of the economic, reasonable and feasible to ensure the construction of the tunnel Safety, but also for the construction of similar tunnel project to provide useful reference and guidance.