为适应重庆轨道交通建设的新环境、新形势，结合重庆主城区地形地貌、地质条件和轨道交通车站特点，本文提出了一种新的大断面深埋轨道交通车站隧道的施工工法——扩大拱脚台阶法。该工法以新奥法为基本理论依据，充分发挥围岩的自稳能力和开挖面的空间约束作用，通过初支大拱脚的设置，将拱部荷载传递至拱脚围岩，从而提高拱部初期支护的承载能力和稳定性。同时，通过分台阶分步开挖，为大断面隧道开挖提供了充足的施工作业空间，有效提高了隧道的施工工效，节约了工程投资和工期。本文以重庆轨道交通九号线工程红岩村站为例，对该工法与双侧壁导坑法进行了对比分析。通过理论计算分析，可以得出扩大拱脚台阶法对围岩的扰动更小，更有利与对围岩的保护和变形控制，工程风险更加可控。

To adapt the new environment and new situation of Chongqing rail transit construction, combined with the topography, geological conditions and characteristics of rail transit stations in the main urban area of Chongqing, this paper proposed a new construction method of large section deep-buried rail transit stations- bench cut method with expanded arch feet. Based on the New Austrian Tunneling Method as the theoretical basis, this construction method gives full play to the self-stabilizing ability of the surrounding rock and the space constraint of the excavation surface, and the load is transferred to the surrounding rock by the setting of the large arch feet of the primary lining to improve the bearing capacity and stability of the arch area of the primary lining. At the same time, through the step-by-step excavation, sufficient construction space is provided for the excavation of large-section tunnels, which effectively improves the construction efficiency of the tunnel and saves project investment and construction period. This paper takes Hongyancun Station of Chongqing Rail Transit Line 9 as a case to compare and analyze this construction method and the double side drift method. Through theoretical calculation and analysis, it can be concluded that bench cut method with expanded arch feet has less disturbance to the surrounding rock, which is more beneficial to the protection and deformation control of the surrounding rock, and the engineering risk is also more controllable.

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