English：

To study the deformation law of stratum and retaining structure caused by deep foundationexcavation construction of a subway station in a water⁃rich soft soil area, a three⁃dimensional numericalanalysis model of dewatering and excavation is established based on a deep foundation excavation projectin the Foshan area and the modified Mohr⁃Coulomb constitutive relationship. The deformationcharacteristics of a foundation excavation caused by dewatering and excavation of a deep foundationexcavation were studied by numerical simulation, and the effect of design parameters of the retainingstructure on controlling deformation was compared and analyzed. The results indicate that the lateraldisplacement mode of the diaphragm wall presents an obvious “concave shape,” and the maximum lateraldisplacement is 0.04%Hw ~ 0.18%Hw. The excavation and dewatering of the foundation excavation willaffect the development of the lateral displacement of the wall, but the lateral displacement of the wallcaused by excavation is about 1. 7~2.4 times that caused by dewatering. With the increase of dewateringand excavation depth, the surface settlement increases significantly. The main settlement deformation isin the range of 0.3Hw ~ 2. 2Hwfrom the foundation excavation, and the maximum settlement is about0.15%Hw ~0. 6%Hw. The maximum settlement point gradually moves outward with the excavation of thefoundation excavation. When the foundation excavation is excavated to the base, the maximum settlementpoint is 1. 2Hwaway from the edge of the foundation excavation. Increasing the stiffness of the inner support can significantly reduce the settlement of the foundation excavation and the lateral displacement ofthe diaphragm wall, but the constraint effect on the foundation excavation and the retaining structure isnot significant when the stiffness increases to a certain extent. Reducing the stiffness of the inner supportwill increase the surface settlement outside the pit and the lateral displacement of the retaining structure,and the deformation range is larger. There is a good fitting relationship between the maximum lateraldisplacement of the diaphragm wall, the peak settlement of the ground surface, and the lateraldisplacement and the insertion ratio of the bottom of the diaphragm wall.