研究目的:城市地铁隧道下穿河流和桥梁时，具有施工难度大、安全风险高的特点，目前，国内在这方面 的类似工程和施工经验较少，围绕这方面的施工技术进行研究和探讨，确保施工安全，具有重要的现实意义。
研究结论:采取在河底铺设防水毯、对地层确保施工安全超前降水、对降水过程进行三维渗流-应力祸合 分析、对隧道超前预加固方案进行比选、对隧道施工过程进行时空效应分析等一系列控制措施竣工后，桥基最 大沉降为 34. 7 mm，最大差异沉降为6. 2mm。工程实践证明施工方案可行，确保了施工安全，提出的地铁隧 道过河过桥施工安全控制模式可供类似工程参考。
Research purposes: The construction is difficult and its risk is high in safety when excavation of metro tunnel crossing bridge and river is conducted. At present, there is a little experience to learn, so it is significant to do research on the construction technology for it for the purpose of ensuring the construction safety.
Research conclusions: The following measures are adopted in order to ensure construction safety : the waterproof blanket is laid on the river bottom, the stratum water is dried by precipitation in advance, the bridge response is predicted with 3D seepage and stress coupled numerical analysis method, the tunnel reinforcing schemes are compared, and the space-time effect of bridge foundation is evaluated by 3D FEM. It shows after taking these measures, the max settlement of bridge foundation is 34. 7 mm, and the max differential settlement is 6. 2 mm. The construction practice proves this construction scheme is reliable and safe, which can provide the reference to similar construction.
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