Numerical Simulation Analysis of the Advantages of Single-story Tunnel Pile Method over Traditional PBA Method and Reasonable Excavation Sequence

In the urban center with complex surrounding environment, it is particularly important to select the construction method of underground excavation station in order to ensure the safety of its own structure and surrounding environment. By introducing the principle of the tunnel pile method and the construction steps of the conventional PBA method and the single-layer pilot tunnel pile method, and comparing the differences between the two methods in terms of whether or not to excavate the lower pilot tunnel, it can be concluded that the single-layer tunnel pile method has less impact on the surrounding environment and better treatment and protection of groundwater. Taking an underground excavation station constructed by a single-layer tunnel pile method in Beijing as an example, FLAC3D is used for numerical simulation to analyze and summarize the influence of different pilot tunnel excavation, different primary support and arch buckle sequence and different secondary lining arch buckle sequence on the vertical and horizontal deformation of the surrounding surface, and the optimal sequence of pilot tunnel excavation, primary support and arch buckle sequence and secondary lining arch buckle sequence are obtained. The study can provide reference for similar engineering design and construction.