上软下硬岩质地层大跨隧道叠合承载拱结构设计分析

Structural Design of the Stacked Loaded Arch of Large-Span Tunnels in Upper-Soft Lower-Hard Rock Stratum

在上软下硬岩质地层中修建浅埋暗挖大跨地铁车站隧道的工程实例较少,选择合理的车站结构型式和施工方法所参照的经验也十分有限。文章以大连地铁兴工街站为背景,通过对上软下硬岩质地层大跨隧道围岩松动特性进行分析和类似工程介绍,提出了一种叠合承载拱新型车站结构型式和相应施工方法,实现单拱大跨车站结构,其结构跨度可达20 m以上,并对该结构的初期支护和二次衬砌设计方法和受力特征进行了介绍。实际应用效果表明,叠合承载拱结构依靠拱部叠合初期支护拱结构承受施工期间全部荷载,在其保护下施工下部结构,可有效控制地层变形,同时适合岩质地层快速机械化施工。

There aren＇t many project cases of shallow large-span tunnel metro stations in rock strata that are soft on top and hard on the bottom, nor is there referential experience for a reasonable structure type and construction method for these metro stations. Based on the Xinggongjie Station of the Dalian metro, a new structure type and construction method named ＂stacked loaded arch for metro stations＂ is presented by analyzing the characteristics of loose surrounding rock of a large-span tunnel in upper-soft and lower-hard stratum, and similar project cases. So a single-arch station structure with a span of more than 20 m can be constructed. The design method and mechanical characteristics of the initial support and secondary lining for a stacked loaded arch structure are analyzed. Application practice shows that the stacked loaded arch with initial support bears the full load in the construction process, the lower structure can be built safely under its protection, ground deformation can he controlled effectively and rapid mechanization construction in rock stratum is feasible.