Abstract: The settlement and deformation in the asymmetric excavation of multilayer deep excavations are important factors affecting the stability of the excavation supporting structures. Numerical simulation of support stability can effectively predict possible problems in the deep excavations. The supporting soldier piles of a subway multi-layer asymmetrical excavation system are analyzed by using the PLAXIS 3D finite element software to construct a wedge-shaped analytical unit. The excavation process of the multi-layer asymmetric excavation is simulated, and the ground settlement, pile top settlement, the horizontal displacement of the soldier pile and the settlement of adjacent buildings and other indicators change are predicted. The deformation monitoring and safety control of the asymmetrical multi-layer excavation are studied. The results show that the horizontal displacement of the pile shaft and the surface settlement increase with the increase of the excavation depth. The settlement of the pile top decreases with the increase of the excavation depth, and the settlement of the adjacent existing buildings decreases with the increase of the distance from the excavation. Numerical simulation results show that the deformation of the excavation is greatly affected by the superstructure, the settlement of the soil near the side of the excavation is about 14% higher than that at the far end, and the horizontal displacement of the soil on the side of the bearing building is about 11% higher than that of the other sides; The comparison results of on-site monitoring and numerical simulation show that the actual deformation process of the excavation is basically consistent with the simulation process, and there is only a slight difference in the stage excavation construction, which shows that the pile-brace joint support method can effectively restrain the deformation of the excavation and make the deformation of the excavation. The index is within the controllable range, and the research results have good engineering guidance for deformation monitoring and safety control during the excavation of asymmetric foundation pits.

Key words: Multi-layer Deep Excavation, Asymmetric Excavation, Wedge Analytical Unit, Settlement Deformation, Numerical Simulation