超深基坑承压水控制技术

Control Technology of Confined Water for Super Deep Foundation Pit

以上海徐家汇中心大厦深基坑降水工程为研究对象,建立了三维渗流模型,进行基坑渗流场模拟,以此预测基坑内外的水位变化情况,用于指导降水井设计和布设。经与坑内外降水水位变化实际进行对比,验证了三维渗流模拟计算的合理性及用于指导降水设计的适用性。由于项目基坑所处区域含有深厚承压水层,地下连续墙无法隔断承压水层,在深开挖工况下基坑极易发生承压水突涌事故,为此,根据计算分析,提出了按需降水控制原则,并通过控制坑外水位来确保周边环境及基坑施工安全。

Taking the deep foundation pit dewatering project of Shanghai Xujiahui Center as the research object,in order to predict the variation of water level inside and outside the foundation pit,three-dimensional seepage model is established to conduct the foundation pit seepage field simulation.This can be used to guide the dewatering well design and layout,and compares them with actual pit precipitation water level variation inside and outside to validate the rationality of the three-dimensional seepage simulation.It can also be used to guide the applicability of the precipitation design.Due to the deep confined water layer in the foundation pit area of the project,the underground diaphragm wall is unable to cut off the confined water layer,hence it is very likely to have the accident of confined water surge in the foundation pit under the working condition of deep excavation.Therefore,according to the calculation and analysis,the principle of dewatering control on-demand is put forward to control the water level outside the pit to ensure the safety of the surrounding environment and foundation pit construction.