基坑施工大面积卸荷对既有地铁区间隧道的影响分析

Analysis on the Influence of Large Area Unloading of Foundation Pit Construction on Existing Subway Tunnel

为了解决城市基坑开挖对下方地铁区间隧道的影响,以西安太华路—北二环立交地下综合管廊工程上跨地铁4号线为背景,采取坑底换填处理措施来控制地铁变形,并通过数值模拟以及现场监测相结合的方式,得到了在管廊施工过程中地铁隧道的变形,以此来评估该工程中采用数值模拟方法的可靠性。结果表明:案例基坑开挖采用围护桩和内支撑方案,以及坑底进行地层换填加固的方式,有效减少了隧道变形,水平向位移基本为0 mm,竖向隆起数值为8.7 mm,区间隧道累计沉降最大值为15.19 mm,并且其他相关技术指标满足安全要求。

In order to solve the impact of urban foundation pit excavation on the subway section tunnel below,taking the Xi'an Taihua Road to North Second Ring Interchange Underground Comprehensive Pipe Gallery Project crossing Metro Line 4 as the background,the pit bottom replacement treatment measures were taken to control the subway and tunnel deformation,and through the combination of numerical simulation and on-site monitoring,the subway and tunnel deformation in the construction process was obtained,so as to evaluate the reliability of the numerical simulation method used in the project.The results show that the excavation of the case foundation pit adopts the scheme of enclosure pile and internal support,and the method of ground replacement and reinforcement at the bottom of the pit,which effectively reduces the tunnel deformation.The horizontal displacement is basically 0 mm,the vertical uplift value is 8.7 mm,the maximum cumulative settlement of the interval tunnel is 15.19 mm,and other relevant technical indicators meet the safety requirements.