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为了明确复杂环境下深基坑开挖对既有地铁隧道的影响,并以此为基础优化基坑支护方案。以典型工程实例为依托,建立基坑施工精细的计算模型,分析了开挖支护结构力学特性,探索了邻近地铁隧道对基坑开挖的力学响应,而后提出了优化方案。研究表明:基坑开挖卸载引起的最大侧移为31.3mm,出现在墙顶下一定深度,连续墙变形整体表现出“鼓肚状”;基坑采用初定支护方案施工对既有地铁结构产生了较为明显的扰动,最大位移为10.7mm,超过了规范规定的预警值;支护方案优化后,基坑开挖引起的地铁隧道结构最大位移为5.6mm,较初设方案小47.7%,满足位移要求,说明方案调整可行。
In order to clarify the influence of deep foundation pit excavation on the existing subway tunnel under complex environment and to optimize the foundation pit support scheme. Based on the typical engineering examples, a detailed calculation model of foundation pit construction is established. The mechanical characteristics of the excavation and support structure are analyzed. The mechanical response of the adjacent subway tunnel to excavation is explored. Then the optimization scheme is proposed. The results show that the maximum lateral displacement caused by unloading excavation is 31.3mm, which occurs at a certain depth under the top of the wall. The deformation of the continuous wall shows “bulging belly” as a whole. The subway structure has obvious disturbances, the maximum displacement is 10.7mm, which exceeds the pre-warning value specified in the code. After the optimization of the support scheme, the maximum displacement of subway tunnel structure caused by excavation is 5.6mm, which is smaller than the initial design 47.7%, meeting the displacement requirements, indicating that the program adjustment is feasible.