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为了探讨第四系松散沉积层地区深基坑降水引起的地下水渗流与地面沉降控制模拟的理论与方法,以南京长江第四大桥北锚碇基坑为例,根据基坑降水过程中有效应力和孔隙水压力的转化关系,建立了深基坑降水三维渗流与地面沉降的耦合模型,并采用三维有限差分方法,模拟了含水层底板埋深达67m,基坑中心承压含水层上部降压段水位降至埋深24.5m时的地下水复杂流动状态及其地面沉降特征;得出了抽水井深度达35m,过滤器埋深为12~35m,28口抽水井联合坑外降水的方案;预测了降水20d后水流达稳定状态的各单井抽水量和基坑周围的地下水位与土体沉降变形量。经后续工程验证该模型正确、可靠,具有重要的工程实用价值。
In order to study the theory and method of groundwater seepage and surface subsidence control induced by deep foundation pit dewatering in the Quaternary loose sediment area, taking the North Anchorage foundation pit of the Fourth Nanjing Yangtze River Bridge as an example, according to the effective stress Pore water pressure, the coupled model of three-dimensional seepage and surface subsidence for deep foundation pit dewatering is established and the three-dimensional finite difference method is used to simulate the embankment depth of 67m, The complicated groundwater flow and ground subsidence characteristics when the water level is reduced to 24.5m buried depth are obtained. The conclusion is drawn that the depth of pumping well is 35m and the depth of filter is 12 ~ 35m. After 20 days of precipitation, the water flow reaches the stable state of each single well pumping water and the pit around the foundation pit and soil settlement deformation. After the follow-up project to verify the model is correct and reliable, with important engineering practical value.