地铁盾构隧道穿越桩基综合处理技术

为研究地铁隧道采用矿山法开挖初期支护+盾构空推拼装管片施工遇桥桩侵入隧道的综合处理技术,以深圳地铁9号线一区间隧道为研究实例,采用理论计算与工程类比相结合方式进行设计,在施工过程中加强施工现场监控量测,并指导施工。先确立处理原则、处理思路和处理范围,再制定洞外支顶、洞内托换的处理方案,最终实施洞外钢管撑支顶、洞内拱顶预注浆加固、初期支护加强、截桩、二次衬砌永久支撑桩基、三次衬砌拼装加强管片补强相结合的综合处理技术。实践证明,采用该综合技术,顺利穿越了桩基,保证了隧道及桥梁结构的安全,对洞内洞外周边的环境影响很小。

Case Study on Treatment of Pile Foundations Encountered in Construction of Shield-bored Metro Tunnel

The pile foundations of an overpass stretches into a shield bored tunnel section on No. 9 Line of Shenzhen Metro. The tunnel section is excavated by mining method, with the primary support installed; then the shield goes through the mined tunnel section, with the segments erected. The tunnel section is designed by means of theoretical calculation and engineering analogy. Strengthened monitoring is made during tunnel construction so as to provide guidance for the tunnel construction. In the paper, the principle, concept and scope of the treatment of the pile foundations are determined, and the scheme of “temporary supporting the overpass and underpinning the pile foundations from inside the tunnel” is established. In the construction, comprehensive construction technologies, including temporary supporting of the overpass by means of steel pipes, pre grouting reinforcement of the tunnel crown made from inside the tunnel, installing strengthened primary support, cutting the piles, permanent supporting of the pile foundations by means of secondary lining, and installing third lining of strengthened segments, are used. The construction practices show that the tunneling has crossed the pile foundations successfully, the safety of the tunnel and the overpass has been guaranteed, and the influence on the environment inside and outside the tunnel has been minimized.