大跨地铁隧道斜井进洞垂直挑顶施工关键技术

Vertical Roof Ripping Construction Techniques for Excavation of Main Tunnel from Inclined Shaft: A Case Study of the Large-span Metro Tunnel in Soft Surrounding Rock

  • 摘要: 针对软弱围岩三线大跨地铁隧道斜井进正洞施工变形不易控制的难题,文章以深圳轨道交通工程新莲区间隧道斜井进正洞段挑顶施工为例,提出了适用于城市地铁隧道工程垂直挑顶进洞的施工方法,阐述了垂直挑顶进洞施工方案、施工流程和施工要点。文章采用数值模拟方法对所提出工法的合理性进行了研究,结果表明:(1)在交叉口处加强支护,采用小导洞爬坡挑顶进正洞是一种有效可行的方法;(2)在斜井与正洞交叉口处设置加强支护可解决因斜井及正洞断面尺寸差距大造成的施工难题;(3)小导洞爬坡挑顶施工为正洞拱架初期支护安装提供了条件,有利于正洞施工快速转换为双侧壁施工工艺;(4)交叉段拱顶围岩存在应力松弛区,通过采取加强支护等措施,该工法对围岩位移控制较优。

     

    Abstract: Aiming at the difficulty of deformation control during construction of main tunnel from inclined shaft for a three-line large-span tunnel in soft surrounding rock, a construction method suitable for vertical roof ripping construction of urban metro tunnel from inclined shaft is proposed by taking the roof ripping construction of Xinlian running tunnel of Shenzhen rail transit as an example, and the construction scheme, procedures and key points are described. Furthermore numerical simulation is adopted to explore the rationality of this construction method. The research results show that: (1) it is an effective way to take roof ripping construction through small pilot tunnel to climb into main tunnel with reinforced support at the intersection; (2) reinforced support at intersection of inclined shaft and main tunnel can solve the construction difficulty caused by large dimension gap between them; (3) roof ripping construction through small pilot tunnel climbing to main tunnel provides precondition for the installation of primary support of main tunnel arch frame and it is favorable for the main tunnel construction which switches to double sidewall construction later; (4) there is a stress relaxation zone of surrounding rock at intersection crown, and the rock mass displacement can be well controlled with roof ripping construction under the help of reinforced support.

     

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