Influence Law of Vertical Layer-incremental Foundation Pit Excavation on Existing Station Structural Deformation

Abstract

Objective Construction disturbances from nearby excavation of foundation pit can cause significant deformation of existing stations in operation, thereby affecting the normal operation of trains. Therefore, it is necessary to study the influence of foundation pit excavation in vertically incremental layers on existing stations located below. Method Taking the construction project of Beijing Subway Line 6 Pingguoyuan Station three-level-section foundation pit as example, the Midas GTS NX finite element software is used to build a foundation pit model. The deformation law of existing station structures caused by deep foundation pit excavation in vertically incremental layers is analyzed, and the simulation results are compared with field monitoring results. Result & Conclusion With the progress of foundation pit excavation, the vertical deformation of existing station structures continuously increases, and the deformation curve of the roof plate exhibits a normal distribution. The mid-span deformation of the station roof is greater than the edge-span deformation, and the vertical deformation at station top is greater than that at the bottom. When the distance between the selected station section and the foundation pit exceeds 9.7 m (approximately 0.81 times the excavation depth), the differential deformation between edge-span and mid-span roof plates disappears. A comparison between numerical simulation data and actual monitoring results reveals that the deformation law of existing stations obtained from numerical simulation analysis is consistent with actual monitoring results, and the maximum deformation is less than the control value of 10.0 mm.

Keywords

• metro
• foundation pit excavation
• existing station