Coupling model of three dimensional seepage and land-subsidence for dewatering of deep foundation pit in loose confined aquifers

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.