Abstract: Dewatering and pit excavation with suspended curtain in Yangtze River floodplain area involve complex stress-flow coupling effect. Based on Biot's consolidation theory and considering the source terms of the pore water pressure caused by dewatering,a fluid-solid coupling numerical analysis model is established to describe the coupling effect of pit excavation and dewatering. The general deformation characteristics of pit excavation and dewatering are studied. The influences of drainage well arrangement and diaphragm wall insertion ratio are analyzed. The results show that:(1)In the stage of dewatering,for the case with dewatering well inside the pit,the diaphragm wall extends the water supply path. The larger the insertion ratio of the diaphragm wall is,the smaller the surface settlement is. For the case with dewatering well outside the pit,the diaphragm wall extends the seepage path. The larger the insertion ratio of the diaphragm wall is,the greater the surface settlement. For the case with dewatering well inside and outside the pit,the surface settlement is inbetween the two cases. (2)When the pit excavation is completed,the total surface settlement is caused by dewatering and the pit excavation,and the latter dominates. The effect of diaphragm wall insertion ratio on the ground settlement during pit excavation is significantly greater than that during dewatering. (3)Dewatering can effectively reduce the roof buoyancy of the confined aquifer,and lead to secondary consolidation of the soil layer,resulting in an increase in effective stress and the strength/stiffness of the soil layer,and effectively reducing the deformation of the stratum during the pit excavation. (4)Dewatering mode and diaphragm wall insertion ratio have little effect on the lateral displacement of diaphragm wall.