以沿海城市的基坑工程为例，分析海相软土地层中基坑施工过程中的主要施工风险，据此提出基坑设计方案和施工技术要点。监测结果表明，围护桩外进行加固能有效控制土体变形，相对未加固区域而言，加固后能降低60%以上的土体变形量；钢筋混凝土支撑拆除可采用先围檩后支撑的顺序，分块施工，减少拆除带来的变形影响；对于凹字形基坑，在凹口的三边进行钢筋混凝土支撑+排桩及局部重力式挡墙的围护结构方式可有效控制凹口内既有建筑物的沉降。

This paper takes the foundation pit engineering in coastal cities as an example to analyze the main construction risks that exist during the entire construction process of foundation pits in marine soft soil layers, and studies the design scheme and construction technology points of foundation pits. The monitoring results show that reinforcement outside the retaining pile can effectively control soil deformation. Compared with the unreinforced area, it can reduce soil deformation by at least 60%. The dismantling of reinforced concrete supports can be carried out in a sequence of first enclosing purlins and then the supporting, with block construction to reduce the deformation impact. This project provides certain technical references for engineering construction under similar geological conditions.

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