基于拱盖法的超大断面暗挖隧道洞内逆作工法关键技术研究

基于拱盖法的超大断面暗挖隧道洞内逆作工法是借鉴"明挖逆作"的施工理念,采用双侧壁导坑法或其他分部开挖工法完成隧道拱部开挖与二衬拱盖施工,在拱盖形成后,隧道中下部断面通过永临结合的支锚体系和合理的施工组织,通过开挖支护与衬砌结构的逆作法施工减小工程风险,降低施工难度;在隧道中下部断面施工阶段,沿隧道纵向、横向、竖向进行三维空间施工组织,为隧道施工提供了充足的施工作业空间.目前,该工法已成功应用于重庆轨道交通环线一期工程民安大道站主体隧道工程建设.通过工程实践证明,该工法在降低工程风险、减小施工难度的同时,能有效提高施工效率、减少工程投资、节约工期.

Key Technology of Top-down Construction Method for Bored Super- large Section Tunnels Based on Arch-cover Method in Soft Rock Areas

The top-down construction method for a bored super-large section tunnel based on the arch-cover method learns from the top-down method used in open-cut structure constructions, which applies the double-side-drift method or other section excavation method to excavate and complete the arch cover secondary lining. After the arch cover is finished, the middle and bottom of the tunnel section will use combined temporary and permanent supports, reasonable construction organization, and cover-and-cut bottom-up methods to reduce engineering risks and difficulties. During the construction phase of the middle and bottom of the tunnel section, the construction organization will develop in three dimensions, offering sufficient space for tunnel construction. This construction method was successfully applied to the Minan Avenue station in the Chongqing rail transit loop line. This project application proved that this construction method can reduce engineering risk and difficulty, enhance construction efficiency, reduce project funding, and shorten the construction period.