为了解决隧道开挖后初期支护侵限引起多次拆换的施工难题，在总结已有软弱围岩开挖技术、支护原理、新奥法隧道支护理论和软弱隧道支护技术的基础上，结合新蜀河隧道监控量测资料，对隧道的施工方法、施工工艺、支护参数、施工中采取的主要措施和取得的施工效果等方面做了大量研究。施工中分别对三台阶法、上台阶加设临时仰拱法和中台阶加设临时仰拱法3种工法工况进行了数值模拟计算和工法试验验证，中台阶加设临时仰拱法效果最好，采用此工法后基本控制了初期支护拆换的问题，节约了施工成本，提高了工效，施工风险也大大降低。

During the construction of New Shuhe tunnel on the second XiangfanChongqing railway, serious deformation occurs after tunnel excavation, which results in the interference of the primary support. In the paper, the construction technologies for tunnels located in soft rock mass with serious deformation potentials are summarized, and case study is made on the construction of New Shuhe tunnel, by means of numerical simulation and construction verification, in terms of “top heading + two benches” method, “top heading + temporary invert” method and “Bench I + temporary invert” method. The study shows that the “Bench I + temporary invert” method is the best solution for the tunnel. “Bench I + temporary invert” method has been adopted for the tunnel, the serious deformation of the tunnel has been brought under control, the construction cost has been reduced, the construction efficiency has been improved and the construction risks have been minimized.