复杂环境下浅埋大跨地铁渡线隧道施工地层沉降控制方法研究

以北京地铁4号线白石桥至学院南路区间渡线隧道作为工程背景,阐述在复杂环境下浅埋大跨隧道施工的地层沉降控制方法。该隧道具有"隧道跨度大(最大跨度22.1 m),埋深浅,断面类型多、结构复杂"等特点,隧道上方有雨水管等市政管线,地层沉降控制难度极大。首先介绍了渡线隧道总体施工顺序安排、超前加固方案和各断面施工方法,并利用FLAC3D三维数值模拟程序,对最大断面开挖支护过程进行了模拟计算,研究了地表沉降规律和塑性区分布情况,用于指导施工。在施工期间对地表沉降进行监测,其结果表明:渡线隧道施工方法是合理的,地表沉降在控制范围内,确保了隧道周边环境的安全。

Study on the Ground Subsidence Control Technology for a Shallow Mined Large-span Metro Crossover Tunnel in a Complex Environment

Taking the crossover tunnel in the Baishiqiao-Xueyuannanlu metro section tunnel of Beijing metro No 4 as the engineering background,the control method for ground subsidence is introduced.The crossover tunnel has such features as a large span,a shallow coverage and many sections with complex structures;in addition,there are also many municipal pipes such as rain water pipe over the tunnel,so the ground subsidence must be restricted strictly to insure the safety of surrounding environment.To achieve it,firstly,the tunnel construction sequence,the tunnel advance consolidation scheme and the excavation method for different profiling tunnels are introduced.Secondly,the FLAC3D numerical simulation procedure is adopted to probe the subsidence rules and the distribution of plastic area.The monitoring results of ground subsidence obtained during construction indicate that the construction technique for the crossover tunnel is reliable and rational.