Deformation Response Research of the Existing Subway Tunnel Impacted by Adjacent Foundation Pit Excavation

Abstract

The excavation of foundation pits is one of the most important factors causing changes to the initial stress state of its surrounding soil, thus affecting the safety of nearby existing subway tunnels. In order to study the deformation in metro lines induced by adjacent foundation pit excavation, a three-dimensional model based on an actual engineering case was established, and the deformation regulations of the retaining wall, surrounding soil, and tunnels were investigated, which also validated the model’s feasibility. Additionally, the deformation and strain response of the subway tunnel under different selection parameters of the enclosing structure and soil were studied. The results showed that, after the foundation pit excavation, the soil inside the pit underwent an uplift, the surrounding soil outside of the pit showed vertical settlement, and the retaining wall created a deformation towards the interior of the pit. Mechanical parameters of plate elements have a small influence on the deformation of metro lines. Axial strain and maximum displacement of the subway tunnel increase with the increase in the soil’s Poisson’s ratio, and on the contrary, they decrease with the increase in the m-value and G 0 , ref . The maximum responses of the subway tunnel came from changes to G 0 , ref and υ . These analysis results can be used for the safety evaluation of subway tunnel operation, design, and construction in other similar engineering settings.

ADF-Net: An Attention-Guided Dual-Branch Fusion Network for Building Change Detection near the Shanghai Metro Line Using Sequences of TerraSAR-X Images

“…Rapid urbanization has increased underground space utilization to relieve traffic congestion. A growing number of excavation projects passing through the upper part of metro tunnels can quickly destroy the initial stress equilibrium state of the surrounding rock [1][2][3][4], especially in Shanghai, where metro tunnels are buried in the soft soil layer [5]. Therefore, timely detection of urban building changes is crucial for monitoring and ensuring ground stability of the surrounding areas of metro lines.…”

Study on the Impact of Deep Foundation Excavation of Reclaimed Land on the Deformation of Adjacent Subway Tunnels

“…Among these projects, the impact of foundation pit construction on adjacent subway tunnels has become a focal point for urban underground engineering construction management. Excavation of foundation pits alters the stress and deformation fields of the soil, potentially leading to stress and displacement exceeding allowable values in subway structures, thus affecting the normal operation of the subway [1][2][3][4][5][6]. Therefore, accurately assessing and predicting the impact of foundation pit excavation on nearby subway tunnels is an urgent issue that needs to be addressed.…”

Deformation of Existing Shield Tunnel Adjacent to Deep Excavations: Simulation and Monitoring Analysis

“…In the field of underground structures and geotechnical engineering, the influence of foundation pit excavation on surrounding tunnels has long captivated researchers. Scholars globally have explored this issue from various angles, including theoretical analysis [1,2], numerical simulation [3][4][5], physical model experiments [6,7], and field monitoring [8][9][10]. Zhang and Wei [11,12] proposed a sidewall unloading model that considers the deformation of retaining structures during excavation, providing essential theoretical support and validating the reliability of their approach.…”