新建排水工程基坑施工对既有地铁隧道的影响分析

Analysis of influence of foundation pit construction of new drainage project on existing subway tunnel

地铁保护区范围内工程施工不可避免地涉及对既有城市轨道交通设施的影响与保护问题.以徐州市津浦东路排水工程基坑上跨地铁1号线盾构区间为背景,采用精细化的数值模拟方法,针对不同基坑开挖卸荷条件下既有盾构隧道的影响进行研究.研究结果表明:一次开挖卸荷20 m,引起隧道结构变位位移大于5 mm,不满足地铁安全保护变形控制值要求;优化后的分段开挖方案,盾构区间的各项变形指标均在安全控制要求范围内;基坑开挖卸荷对隧道结构的受力状态影响较小,经检算,隧道结构的受力状态基本未改变,隧道主要呈压弯受力.

The project construction within the Metro protection area inevitably involves the impact and protection of the existing urban rail transit facilities.Based on the background that the foundation pit of the drainage project of Jinpu East Road in Xuzhou crosses the shield section of Metro Line 1,the influence of the existing shield tunnel under different excavation and unloading conditions is studied by using the refined numerical simulation method.The results show that the displacement of the tunnel structure caused by the unloading of 20 m in one excavation is more than 5 mm,which does not meet the requirements of the deformation control value of the subway safety protection;the deformation indexes of the shield interval are all within the scope of the safety control requirements in the optimized section excavation scheme;the excavation and unloading of the foundation pit has little influence on the stress state of the tunnel structure,after checking and calculating,the stress state of the tunnel structure is basically unchanged,and the tunnel is mainly in the form of compression and bending.