复杂条件下超浅埋双层叠合大断面隧道下穿敏感建筑设计

Design for a Super-Shallow Large-Section Double-Level Tunnel in Complex Conditions Underneath Sensitive Buildings

  • 摘要: 文章结合目前国内世界级工程港珠澳大桥的拱北隧道,从设计的角度介绍了一种饱和富水软土地层超浅埋大断面双层叠合六车道隧道下穿敏感建筑的新方法——管幕-支护结构组合体系浅埋暗挖法。该法将作为超前支护的管幕与作为支护结构的初期支护进行合理组合连接,形成大刚度的环向及纵向整体受力体系,可有效控制隧道开挖过程及运营阶段的地表变形,大幅度降低施工风险。该法通过对管幕间的土体进行冻结的方式形成隔水帷幕,避免了由于地下水流失导致的地面变形及隧道暗挖施工期间产生涌水、突泥现象,隧道能够在水密性的地下空间进行施工。该法运用了顶管、冷冻两种在隧道建设领域运用较少的新工艺,经过与支护结构的合理组合,成功地解决了复杂地质条件及复杂环境条件下的超浅埋大断面隧道下穿敏感建筑遇到的技术难题,拓展了隧道建设新思路,建立了隧道建设新方法。

     

    Abstract: In light of the Gongbei tunnel in the Hong Kong-Zhuhai-Macao Bridge, which is a current world-class project in China, this paper introduces a new construction method: shallow mined excavation with a combination pipe roof and supporting structure system for the construction of a super-shallow large-section tunnel with six lanes and two levels underneath sensitive buildings in water-rich soft ground. In this method, the pipe-roof advance support and the supporting structure as the primary support are combined and connected to form an integrated circumferential and longitudinal load system with great stiffness, which can effectively control surface deformation during tunnel construction and operation and significantly reduce construction risks. Using this method, a waterproof curtain is formed by freezing soil between the pipes to avoid the surface deformation caused by loss of groundwater and the water- and mud-bursting that occurs during excavation, as well as to ensure excavation in a water-tight underground space. Pipe-jacking and ground freezing, which are rarely used in tunnel construction, have been combined reasonably with the supporting structure, successfully solving the technical problems of constructing a super-shallow large-section tunnel underneath sensitive buildings in complex geological and environmental conditions. A new concept and method for tunnel construction has been developed.

     

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