Study on the mechanical mechanism and influence zone of foundation pit construction adjacent to existing subway station

Abstract The excavation of foundation pits can result in additional displacement and stress on existing underground structures. This will inevitably affect their functional use and operational safety. In this study, model tests and numerical simulations were employed to investigate the influence of foundation pit construction on the existing subway station, diaphragm wall, and surface settlement. Meanwhile, the deformation mode of the existing subway station and mechanism of the foundation pit construction were analyzed. Finally, the influence zone of foundation pit construction for adjacent stations was proposed based on adjacent coefficient. The research results indicate that the maximum vertical displacement of the station structure caused by foundation pit construction is −4.47 mm. A leftward inclination deformation mode is exhibited by the existing station structure with the foundation pit excavation. There is a certain correlation between proximity coefficient ( k ) and differential settlement. When 0.1 ≤ k < 6.0, it is a strong influence zone, and when k ≥ 6.0, it is a weak influence zone. The research results of this paper can provide reference for similar underground engineering construction.