Mechanical Deformation Analysis of Pit-in-Pit Asymmetric Deep Foundation Pit

In order to study the influence of shaped pit-in-pit excavation on the mechanical deformation of foundation pit, this paper analyses the influence of asymmetric pit-in-pit excavation on the deformation and stability of foundation pit with the background of Guangzhou Baiyun Station Foundation Pit Project, based on the on-site monitoring data and the restoration of the on-site construction model by the finite element software Plaxis 3D. The results show that: The asymmetric excavation of the foundation pit leads to the asymmetric horizontal displacement of the supporting structures on both sides, the deformation of the ground-connected wall on the over-excavated side increases gradually with the increase of the excavation depth of the inner pit, while the ground-connected wall on the non-over-excavated side shows the phenomenon of displacement push-back with the excavation of the inner pit; it is recommended to strengthen the monitoring and protection of the ground-connected wall on the over-excavated side and the central area during the construction; at the same time, due to the characteristics of the foundation pit of oversize and extra width, the support axial force in the central part of the foundation pit will. At the same time, due to the super large and super wide characteristics of the foundation pit, the support axial force in the middle of the foundation pit will dissipate, making the central support axial force smaller than the corner axial force, especially after the excavation of Zone 2, the corner support axial force will change suddenly, so the actual project needs to pay special attention to this kind of deformation.