Abstract: Compared with the bottom type of cutoff walls, the suspended cutoff wall is more prone to produce larger surface deformation outside the excavation after dewatering, so it has an important engineering significance for the research. The case history of a deep excavation project of Kunshan City Square is presented in this paper. A 3D dewatering model was established by using GMS MODFLOW to simulate the actual project dewatering conditions. The influence of dewatering rate, dewatering well layout and recharge rate on the dewatering effect was analyzed. The results show that the water level outside the excavation is basically in a stable state after 10 days of depth reduction, and the water level outside the excavation changes greatly on the first day of dewatering. Under the same total amount of dewatering, the layout of dewatering well has the same effect on the water level outside the excavation. The drop depth of water level outside the excavation increases with the insertion depth of filter pipe. The water level outside the excavation can be kept in a safe state by keeping the recharge and dewatering amounts above 70%.

Key words: Deep Excavations, Suspended Cutoff Wall, Dewatering, Recharge