Deformation Law Analysis of Metro Station Deep Foundation Pit Constructed by Cover-Excavation Reverse Method in Sandy Area

Objective Stress deformation characteristics of the main structure in the process of metro station construction by cover-excavation reverse method are relatively complex. The construction mechanics process of the subway station in the sandy area is even more complex, which greatly increases the construction difficulty of the foundation pit in this area. Therefore, it is necessary to conduct in-depth research on the deformation characteristics of metro station deep foundation pit constructed by cover-excavation reverse method in sandy area. Method Based on a metro station project in Shenyang City, the deformation characteristics of deep foundation pit cover excavation reverse construction in water-rich deep sandy stratum is elaborated. Numerical simulation is used to analyze the change law of diaphragm wall horizontal displacement, slab displacement, neutral pillar displacement and differential settlement between diaphragm wall and adjacent neutral pillar during foundation pit construction. Result & Conclusion The results show that the displacement deformation of diaphragm wall is significantly affected by the construction of the foundation pit, and its horizontal lateral displacement deformation increases continuously following the excavation depth of the foundation pit increase, with all deformation mainly towards the direction of the pit. The slabs play a good supporting role, effectively controlling the horizontal displacement of the enclosure structure, and manifesting mainly as heave deformation, among which the roof plate is most affected by the foundation pit construction. The neutral pillar is deformed in both vertical and horizontal directions, mainly in the form of vertical heave deformation due to soil unloading effect of the deep foundation pit. The differential settlement of the diaphragm wall and the neutral pillar increases gradually with the construction progress, and reaches the maximum in the excavation of the underlying soil.