跨越既有隧道桥基施工保护措施与影响分析

Measures Minimizing Bridge Foundation Construction Impact on the Nearby Existing Tunnel

从常州水文地质状况出发,分析了富水砂层地质条件下地铁隧道对周围环境的敏感性,依托新桥中桥工程上跨地铁1号线隧道项目,详细分析了跨越既有隧道桥基钻孔灌注桩施工所采取的一系列地铁保护措施,并对施工期间地铁隧道结构进行了保护监测,监测结果表明:针对钻孔灌注桩施工风险采取的地铁结构保护措施效果显著,整个桩基施工期间,地铁隧道变化量均在控制范围以内,隧道结构安全;距隧道5 m以上的桩基施工对隧道影响较小,变形主要发生在两隧道中间桩基施工期间;地铁隧道结构对外部振动荷载较为敏感,需慎重考虑施工中振动荷载对轨道管片变形的影响;受桩基分布密度影响,桥梁正向投影区域隧道变形较大,向两侧逐渐减小,呈槽型分布。投影外侧10 m左右,隧道基本无变化。

Based on the hydrogeological conditions of Changzhou,this paper analyzes the sensitivity of subway tunnel to the geological condition of groundwater bearing sand layer.A case history of Xinqiaozhongqiao highway over existing Metro Line No.1 is presented.This paper also analyzes a series of protective measures for the subway construction near the bored pile and monitors the subway tunnel structure during the construction period.The monitoring results show that,in the project,the protection measures for the construction risk of cast-in-place bored pile are effective.During the whole pile foundation construction process,the changes of the subway tunnel are within the control range,and the tunnel structure is safe.The monitoring data also reflect that the pile foundation construction with a distance of more than 5 mfrom the tunnel has a small impact on the tunnel.The deformation mainly occurs during the construction of the pile foundation in the middle of the two tunnels.The structure of the subway tunnel has a significant impact on the construction of the tunnel The external vibration load is relatively sensitive,so it is necessary to carefully consider the impact of vibration load on the deformation of track segment during construction;due to the impact of pile foundation density,the tunnel deformation in the forward projection area of the bridge is relatively large,gradually reducing to both sides,and the overall distribution is in the groove shape.The tunnel is basically unchanged about 10 moutside the projection.