Response Monitoring and Analysis in Deep Foundation Pit Excavation: A Case Study in Soft Soil at Subway Tunnel Intersections

Abstract

With the rapid development of urban rail transit and underground space development, the occurrence of excavation near existing tunnels is becoming more common. This excavation and unloading will inevitably cause soil deformation outside the pit and the tunnel buried therein. This paper presents an investigation into the entire excavation process and the deformation effects on the adjacent subway structure under complex construction environments, including soft soil foundations and adjacent subway intersections, based on measured data of pit construction. The horizontal and vertical displacements of deep soils in two pits were analyzed along with safety management measures to determine the horizontal displacement curve pattern and the lateral displacement development distribution law of deep soils. The analysis of subway deformation data shows that after excavation, the subway tunnel undergoes “lateral expansion” and “vertical compression” type deformation, accompanied by “in-pit” horizontal displacement and “settlement” vertical displacement. Furthermore, a correlation analysis reveals a clear linear relationship between pit deformation and subway structure deformation, which can be used as a prediction method for adjacent structure deformation. Finally, a comparative analysis of existing relevant influence zone models and tunnel deformation prediction formulas is carried out based on the monitoring. The results of this study have significant guiding implications for the excavation construction of soft soil foundations in the vicinity of subway crossings.

Intelligent Analysis of Construction Safety of Large Underground Space Based on Digital Twin

“…Construction safety risk data are the basis of driving the digital twin framework Therefore, the construction risk index system of large underground spaces is first con structed through a literature research and expert interviews. The construction risk of ur ban underground large space engineering is mainly divided into [15][16][17][18] retaining struc ture instability, support system instability, pit bottom deformation and failure, soil col lapse, surface subsidence, building (structure) damage, road and bridge damage, and un derground pipeline damage, etc., as shown in Figure 1.…”

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.…”

Numerical Simulation Study on Application of T-Shaped Composite Pile Support System in Super-Large Foundation Pit Support Engineering

“…In the current urban environment, foundation pits have the characteristics of a very large scale, ultra-deep size, narrow space, tight construction schedule, and complex surrounding environment. Improper support methods can easily lead to the risk of surface tilt, ground settlement, and even collapse; the deformation of deep foundation pits near subway lines can especially affect subway construction [1][2][3][4]. Yang et al [5] studied the deformation law of deep and large foundation pits in soft soil layers in Fuzhou City.…”