新建铁路基坑开挖稳定性分析及对既有铁路影响

Analysis on Stability of Foundation Pit Excavation for New Railways and Its Impact on Existing Railways

摘要:

以通苏嘉甬铁路跨宁波绕城高速特大桥为背景，采用PLAXIS3D软件进行数值分析，并与理论计算相结合的方法研究跨铁路线路的基坑开挖的稳定性及对既有铁路的影响。结果表明：新建桥梁95#、103#承台基坑采用钻孔灌注桩+内支撑+坑底加固的支护体系，其整体稳定性、抗渗流、抗倾覆、坑底抗隆起、墙底抗隆起安全系数均能满足基坑安全等级一级要求；对不同工况下的数值分析结果表明桥墩和承台变形均满足要求，基坑防护体系合理，开挖过程可确保既有铁路的安全；全程监测既有铁路桥墩的变形，并与理论值进行对比，判断既有桥墩的变形，并对铁路运营安全进行预警。

Abstract:

Based on the special bridge of the Tongzhou-Suzhou-Jiaxing-Ningbo Railway crossing the Ningbo Ring Expressway, the PLAXIS3D software is used for numerical analysis, and the method combined with theoretical calculation is adopted to study the stability of foundation pit excavation across railway lines and its impact on the existing railway. The results show that the supporting system of cast-in-place bored piles, internal bracing and pit bottom reinforcement is used for 95# and 103# base slab foundation pits of the new bridge, and the safety factors of overall stability, anti-overturning, anti-seepage, anti-heave at the pit bottom, and anti-heave at the wall bottom all meet the requirements for Safety Grade Level 1 of foundation pit. The numerical analysis results under different working conditions show that the deformations of both the bridge piers and the base slabs all meet the requirements. The foundation pit protection system is reasonable, and the excavation process can ensure the safety of existing railways. The deformation of existing railway bridge piers is monitored throughout the process. Compared with the theoretical values, the deformation of existing bridge piers is judged, and the early warnings for railway operation safety is issued.