深基坑对紧邻地铁盾构区间隧道变形的影响性分析

Influence Analysis on Adjacent Metro Shield Tunnel's Deformation Caused by Excavation of Deep Foundation Pit

基于某城市深基坑施工紧邻既有城市地铁车站及区间隧道的工程情况,采用三维数值模拟手段对在3种不同加固方式下区间隧道的水平位移和竖向位移进行对比分析研究。得出了基坑开挖地下3层～5层时,对隧道的水平侧移影响较为显著;而基坑开挖第1层时,由于坑外土体受地下连续墙向外的压力作用,导致区间隧道管片存在竖向隆起现象,建议给予重点关注。同时通过对比3种不同加固方案,仅有第2种加固方式满足规范要求,建议给予采用。

Based on the actual project situation of a deep foundation pit which is excavated near the existing metro station and metro tunnel, this article analyzes the horizontal displacement and vertical displacement of the metro tunnel under three different strengthening schemes by using three dimensional numerical simulation method. This study draws conclusions that, when the excavation depth reaches from the third layer to the fifth layer underground, the excavation of the foundation pit has obvious influence on the horizontal displacement of the tunnel structure. It also shows that after the first layer underground is excavated, then because of the outward pressure on the soil outside of the pit caused by the underground diaphragm wall, the vertical upheaval phenomenon occurs in the tunnel segments which should be paid more attention. In the end, comparing the three strengthening schemes, only the second scheme will meet the requirements of relevant standards, so the second scheme is recommended.