摘要:
以上海环球金融中心基坑降水为例,根据基坑降水过程中有效应力和孔隙水压力的转化关系,建立了基坑降水与地面沉降的耦合模型,并采用有限差分数值模拟方法,模拟了在多层含水层复合存在、含水层最深底板埋深达145 m、基坑周围挡水连续墙埋深达34 m、抽水井埋深达55 m、抽水井过滤器埋深为34～55 m,单井抽水量为1420 m3/d的8口抽水井联合降水情况下,基坑中心下伏第Ⅰ承压含水层上部降压段水位降至埋深26 m时的地下水复杂流动状态及其地面沉降特征。经后续工程验证,该结果正确、可靠,该理论用于模拟预测此类地区深基坑降水引起的地下水流场变化及其地面沉降具有较高的可信度。
Abstract:
Based on the translation relation between effective stress and pore water pressure,a coupling model between deep dewatering of deep foundation pit and land-subsidence was established.Three dimensional finite difference numerical simulation method was applied to dewatering of foundation pit in Shanghai Huanqiu Finance Center,and the complicated flow state of groundwater and character of land-subsidence were simulated under these conditions where the aquifers deposited layer by layer,the bottom of the aquifers embedded up to 145 m in depth,the horizontal flow barrier embedded up to 34 m in depth,the extraction wells were penetrated up to 55 m in depth,the filters of the extraction wells were located between 34 55 m in depth,eight extraction wells with the quantity of pumping water for each being 1420 m3/d were operated at the same time,and the water level of the upper part of confined aquiferⅠunder the center of foundation pit was decreased to 26 m under land surface.The result was proved to be correct and reliable by follow-up project.It was concluded that it was very reliable to use the theories to simulate and predict the variation of groundwater flow and land-subsidence caused by dewatering of deep foundation pit in such areas.
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