某城市核心区软土超深基坑支护设计方法与实践

Design Method and Practice of Ultra-deep Foundation Pit Supporting in Soft Soil of Urban Core Area

摘要:

城市核心区的软土深基坑工程面临着地质条件差、环境保护要求高、地下水控制困难等难题，需要合理选择基坑围护和支撑方案。以上海市某深基坑项目为例，针对基坑周边环境复杂、承压水层相互连通等特点，采用地下连续墙加高压旋喷桩加内支撑的支护设计，并对承压含水层采取止降结合的技术措施，并通过有限元分析的方法模拟了基坑开挖对周围环境的影响。监测成果表明，基坑及周边环境的变形均满足设计要求，验证了支护方案的可靠性，可为类似软土超深基坑工程提供参考。

Abstract:

The soft soil deep foundation pit project in the urban core area is faced with problems such as poor geological conditions, high requirements of environmental protection and difficult groundwater control. It is necessary to select an appropriate enclosure and supporting scheme for foundation pit. Taking a deep foundation pit project in Shanghai as an example, in view of the complex surrounding environment of the foundation pit, the interconnection of confined aquifer and the other features, the supporting design of diaphragm wall, high-pressure jet grouting pile and internal supporting is adopted, and the technical measures of combining the stop and drop are taken for the confined aquifer. The impact of foundation pit excavation on the surrounding environment is simulated through the finite element analysis. The monitoring results show that the deformations of the foundation pit and the surrounding environment meet the design requirements, which verify the rationality of the supporting and can be referred for the similar soft soil foundation pit projects.