关键词: 深基坑, 地铁隧道, 有限元计算, 变形分析, 地铁保护区

Abstract: The excavation and unloading of foundation pits inevitably cause disturbance to the surrounding rock and soil, which in turn has adverse effects on adjacent existing subway tunnels. A finite element modeling analysis method was used to comprehensively analyze and evaluate the total displacement, horizontal, and vertical displacements of the adjacent underground tunnel caused by the entire process of the supporting structure construction, deep excavation, basement construction, demolishing and backfilling, and the upper structure construction for a deep foundation pit project near a subway tunnel in Shenzhen. Research has shown that by comparing the overall displacement, horizontal and vertical displacements estimation results of tunnel structures under various working conditions, the deformation of tunnel structures caused by the excavation of foundation pits is mainly manifested as the horizontal and vertical displacements can be basically neglected. Comparing the displacement of the left and right tunnel lines under various working conditions, the closer the distance to the foundation pit, the greater the overall displacement, horizontal and vertical displacements of the tunnel structure caused by excavation. The overall displacement, horizontal and vertical displacements caused by the excavation of the foundation pit gradually increase with the excavation process, reaching an extreme value when the foundation pit is excavated to the bottom, and then gradually decreasing. The overall displacement and deformation of the subway tunnel caused by the excavation of the project foundation pit under various working conditions meet the control requirement of 5mm deformation control for Shenzhen subway tunnels. 

Key words: Deep Excavation, Subway Tunnel, Finite Element Analysis, Deformation Analysis, Subway Protection Area