软土地区深基坑工程降水设计及施工

DEWATERING DESIGN AND CONSTRUCTION OF DEEP FOUNDATION PIT ENGINEERING IN SOFT SOIL AREA

上海某超高层项目工程中,浅层土层、中层土层和深层土层的地下水赋存状态有很大差异。本工程前期进行了水文专项抽水试验,根据试验结果制订了布置真空疏干井、减压深井的降水对策。同时,为避免基坑微承压水突涌,利用压力平衡原理,对场地内的3层微承压含水层分别进行了抗突涌验算。确定了每层微承压水自然水位埋深条件下的临界开挖深度和不同开挖深度下每层微承压含水层的安全水位要求,保障了基坑开挖施工的安全性,为基坑环境保护提供了理论依据。

In a super high-rise project in Shanghai,there are great differences in the occurrence of groundwater in shallow,middle and deep soil layers.In the early stage of the project,a special hydrological pumping test was carried out,and based on the test results,the drainage countermeasures for the layout of vacuum dredging wells and decompression deep wells were formulated.At the same time,in order to avoid the inrush of micro-confined water in the foundation pit,the three layers of micro-confined aquifer in the site were checked against inrush by using the principle of pressure balance.The critical excavation depth under the condition of the natural water level of each layer of micro-confined water is determined,and the safety water level requirements of each microconfined aquifer under different excavation depths are determined to ensure the safety of foundation pit excavation and construction,which provides pit environmental protection a theoretical basis.