基坑开挖对近接地铁隧道的影响分析

Influence Analysis of Foundation Pit Excavation on Adjacent Metro Tunnels

摘要: 为精准控制深基坑开挖对邻近运营地铁隧道的结构变形风险，本文以郑州某邻近运营地铁2号线的商业综合体深基坑为研究对象。结合场地地勘数据，在原“土钉墙 + 双层帷幕”支护方案基础上，以“土钉墙布设与否、帷幕层数(单层/双层)”为变量，优化设计3种新方案。应用Midas GTS NX软件建立三维有限元模型，模拟基坑开挖全过程，对比各方案下基坑及地铁隧道的位移响应及工程经济性。研究表明：“45˚放坡无土钉 + 双层帷幕”的优化方案(方案一)综合效益最优，基坑及邻近隧道的最大位移均满足位移允许值，且相较于原方案，工程造价降低了3.7%。此外，基坑关键部位位移的现场监测数据与有限元模拟值相对误差仅3.2%~9.5%，高度吻合，有效验证了所建模型在该工程条件下变形预测的可靠性，可为同类近接地铁深基坑工程提供技术参考。

Abstract: To accurately control the structural deformation risk of adjacent operational metro tunnels caused by deep foundation pit excavation, this study took a deep foundation pit of a commercial complex adjacent to the operational Zhengzhou Metro Line 2 as the research object. Based on the site geological survey data, and on the basis of the original “soil nailing wall + double-layer curtain” support scheme, three new schemes were optimized and designed with “whether to arrange soil nailing walls and the number of curtain layers (single-layer/double-layer)” as variables. The Midas GTS NX software was used to establish a 3D finite element model to simulate the entire process of foundation pit excavation, and the displacement responses of the foundation pit and adjacent metro tunnels as well as the engineering economy under different schemes were compared. The research showed that the optimization scheme (Optimization Scheme 1) of “45˚ slope without soil nailing + double-layer curtain” had the best comprehensive benefits. The maximum displacements of the foundation pit and adjacent tunnels all met the displacement allowable values, and compared with the original scheme, the project cost was reduced by 3.7%. In addition, the relative errors between the on-site monitoring data of displacements at key parts of the foundation pit and the finite element simulation values were only 3.2%~9.5%, showing a high degree of consistency. This effectively verified the reliability of the established model in deformation prediction under the engineering conditions of this project, and can provide technical reference for similar deep foundation pit projects adjacent to metro lines.