轨道交通大断面深埋隧道施工工法——扩大拱脚台阶法

为适应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，提出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，能够为大断面隧道开挖提供充足的施工作业空间，有效提高隧道的施工工效，节约工程投资、缩短工期。以重庆轨道交通9号线红岩村站为例，对该工法与双侧壁导坑法进行对比分析。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，更有利于对围岩的保护和变形控制，工程风险更加可控。

Construction Method for Large Section Deep-buried Rail Transit Stations: Bench Cut Method with Expanded Arch Feet

To adapt to the new environment and situation of Chongqing''s rail transit construction, this study proposes a new construction method for large-section deep-buried rail transit stations: the bench cut method with expanded arch feet. This method considers the topography, geological conditions, and characteristics of rail transit stations in the main urban area of Chongqing. Based on the New Austrian Tunneling method, it utilizes the self-stabilizing ability of the surrounding rock and space constraint of the excavation surface, transfers the load to the surrounding rock by setting large arch feet of the primary lining, and improves the bearing capacity and stability of the arch area. Additionally, step-by-step excavation provides sufficient construction space for the excavation of large-section tunnels, effectively improving construction efficiency and saving project investment and time. The Hongyancun Station of Chongqing Rail Transit Line 9 serves as a case study to compare and analyze this construction method and the double-side drift method. The bench-cut method, with expanded arch feet, causes less disturbance to the surrounding rock, is more beneficial for the protection and deformation control of the surrounding rock, and is more controllable in terms of engineering risk.