NUMERICAL SIMULATION OF THREE-DIMENSIONAL SEEPAGE FIELD OF A DEEP FOUNDATION PIT DURING DEWATERING IN A COMPLEX COMPOSITE AQUIFER SYSTEMCASE STUDY OF DEWATERING OF A PIT AT THE SHANGHAI FINANCE CENTER

Multi-layer loose and thick Quaternary sediments in the Yangtzi River delta create a complex aquifer system.Partial pumping wells used in dewatering project and the diaphragm wall not attached to the bottom of layer around pits result in a very complex characteristic of three-dimensional groundwater seepage in the foundation pit.In this paper authors use the dewatering of the foundation pit at Shanghai Finance Center as a case study to demonstrate how the three-dimensional finite-difference numerical method can be used to characterize the groundwater seepage in the foundation pit.It is a multi-layer aquifer system with a confining layer at a depth of 149 m,a pits diaphragm wall at a depth of 34 m and an anticipated water level drop of 26 m within the pit.An optimized method for dewatering of the foundation pit is eventually derived.