城市水下暗挖隧道修建关键技术研究

Key Construction Techniques for Urban Underwater Bored Tunnels

  • 摘要: 修建水下隧道目前已成为城市越江的一种重要方法。文章结合长沙市营盘路隧道工程修建实例,探讨了城市水下隧道的一些创新性设计和施工方法。在深入分析既有水下隧道埋深确定方法存在问题的基础上,提出了考虑工程控制措施的水下隧道最小埋深确定方法。采用该方法确定营盘路隧道的最小埋深为11.5 m,较国内外既有方法埋深减小5 m以上,隧道长度减少近400 m。采用“以堵为主,限量排放”的防排水原则,通过对注浆加固圈厚度及加固参数的调整,可减少水下隧道运营期间隧道内的渗水量。采用超前全断面预加固、双层初期支护等手段,通过合理的开挖分部和施工组织,成功开挖了覆跨比仅为0.46、隧道开挖面积达376 m2的水下超浅埋大断面隧道,解决了水下超大断面隧道多工序、多断面施工的难点。

     

    Abstract: Considering that underwater tunnels are important river-crossing passages in urban areas at present, and using the construction of the Yingpan road tunnel in Changsha city as an example, some innovative design and construction methods are discussed for urban underwater bored tunnels. A method for determining minimum overburden is put forward based on the consideration of engineering control measures and analysis of the problems with existing methods, by which the minimum overburden is determined to be 11.5 m (more than 5 meters shallower than under existing methods in China and abroad) and the tunnel length is reduced by nearly 400 m accordingly. The water seepage during tunnel operation could be reduced by adopting a “blocking-based limited drainage” principle and adjusting grouting-ring thickness and relevant reinforcement parameters. A shallow-buried large-section underwater tunnel with a depth/span ratio of 0.46 and excavation area of 376 m2 is completed successfully using advance full-face pre-reinforcement, a double-layer primary support, a reasonable excavation section division, and proper construction arrangements.

     

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