摘要:降水可为基坑的开挖提供良好的施工环境，对周围土体加固、支护结构的稳定和水压力减小有很大的作用。同时降水也会使基坑渗流场变得复杂，可能会引起流土、流砂、管涌等灾害，还会使基坑外侧地下水位下降而导致土层固结引发地面沉降。因此必须重视基坑开挖和降水对基坑和邻近建筑物的影响。本文以上海某基坑项目为例，根据场地工程地质和水文地质条件、围护结构设计深度和基坑开挖深度，建立地下水渗流数值模型，进行基坑降水设计，然后通过抽水试验调整后期的抽水运行方案，进而指导施工安全顺利的推进，并为同类型基坑工程的设计与施工提供一定的参考。

Abstract: The precipitation can provide a good construction environment for the excavation of the foundation pit, which has significant effects on the stabilization of the surrounding soil, the stability of supporting structure and the reduction of hydraulic pressure.At the same time, precipitation can lead to complicated seepage field of foundation pit, which may cause disasters such as flowing soil, flowing sand, piping, and etc. Ground subsidence also can be caused because of the soil consolidation induced by the fall of the groundwater level in the foundation pit.Therefore, attentions must be paid to the influence of foundation excavation and dewatering on the foundation pit itself and its surrounding buildings. Taking a foundation pit project in Shanghai as an example, this paper establishes a numerical groundwater seepage model according to the site conditions of engineering geology and hydrogeology, design depth of enclosure structure and pit excavation of metro station. Then, a pumping operation plan is tested and adjusted using the model to guide the construction safely and smoothly, which provides references for the design and construction of the same type of foundation pits.