大断面软弱地层隧道三台阶四步交错法开挖施工技术

On the Application of the 3-Bench-4-Step Alternative Excavation Method to Large-Cross-Section Tunnels in Weak Strata

新建赤峰至喀左铁路工程的建平隧道施工过程中,采用“三台阶四步交错法”开挖方法,介绍了隧道开挖方法的施工特点、施工工艺流程和关键施工技术。与设计推荐的“三台阶七步开挖法”或“三台阶临时仰拱法”开挖方法相比,减少了施工步骤、加快了施工进度、提高了工作效率,缩短了从掌子面开挖至初期支护封闭成环的时间,提高了施工安全系数。“三台阶四步交错法”开挖施工技术适用于公路、铁路、高速铁路大断面软弱地层中的隧道开挖施工。

As the 3-Bench-4-Step Alternative Excavation Method is applied to the construction of the Jian-Ping Tunnel of the newly-built Chifeng-Kezuo Railway Project,introduced in detail in the present paper are the construction characteristics of the tunnel-excavating method,the excavation construction technological process,and the key construction techniques.Compared with the 3-Bench-7-Step Excavation Method or the 3-Bench-Temporary-Inverted Arch Method recommended in the Design Scheme,the 3-Bench-4-Step Alternative Construction Method helps reduce construction steps,quicken the construction progress,improve the construction efficiency,shorten the duration time between the starting time of excavating the work face and the initial support and the ring-forming time and increase the construction safety coefficient.The excavation construction technique of the 3-Bench-4-Step Alternative Construction Method may be applied to the large-cross-section excavation construction of tunnels of highways,railways,high-speed railways in weak strata.