上下层小净距重叠隧道复合仰拱支护工法研究

Research on Composite Inverted Arch Supporting Method for Small Spacing Overlapping Tunnels

采用常规施工方案修建小净距重叠隧道时,存在施工风险高、工期长、经济性差等诸多缺点。以重庆铁路枢纽东环线鸡公咀、芭蕉沟重叠隧道为背景,提出一种适用于小净距重叠隧道施工的新方法,并从基本原理和数值计算两个方面对其可行性进行初步探讨,研究结果表明:(1)该工法通过复合仰拱形成了有效的支护承载体系,既降低了下层隧道二衬特殊加强、保护措施的工程投入,也加快了工程进度;(2)上下层隧道支护结构的变形值能够满足规范要求,截面承载能力具有一定的安全储备,夹岩应力状态稳定,重叠隧道支护体系安全可靠。

There are many disadvantages in constructing small spacing overlapping tunnels with a conventional construction scheme, such as high construction risk, long construction period and poor economy. With reference to overlapping tunnels of the Chongqing East Ring Road, a new method for the constructing small spacing overlapping tunnels is proposed. The feasibility of this method is discussed from two aspects of basic principle and numerical calculation. The results show that:(1)The method forms an effective supporting bearing system through the composite invert arch, reduces the engineering investment of special reinforcement and protection measures for the second lining of the lower tunnel, and significantly improves the construction efficiency and progress.(2)The deformation values of the upper and lower tunnel support structures can meet the specification requirements;the supporting normal section bearing capacity has certain safety reserve, the rock is in a stable state and the support system of overlapping tunnels is safe and reliable.