摘要：研究目的:邻近既有铁路桥梁修建新的建筑物,由于建筑物的基础对土层应力会产生附加应力,不可避免引起既有铁路桥梁基础发生变形.新建石家庄至济南客运专线济南西联络线特大桥下穿京沪高速铁路黄河南引桥,京沪高速铁路采用无砟轨道,为确保列车的运营安全,对轨下桥梁结构的沉降要求非常严格,需要对下穿方案引起京沪高速铁路桥梁沉降进行分析.本文石济客专下穿桥梁桥墩分别按实体墩和框架墩两种结构方案,采用Plaxis三维有限元程序对京沪高速铁路桥梁沉降影响进行分析,以确定影响最小的结构方案,稳定线路走向.研究结论:分析结果表明:(1)考虑新建桥梁引起的基础附加沉降,既有京沪高速铁路桥梁相邻墩最大不均匀沉降实体墩方案最大3.2 mm,框架墩4.3 mm,均在规定的5 mm以内,下穿方案可行；(2)实体墩方案影响最小,推荐石济客专桥梁采用实体墩方案；(3)适当延长新建桥梁的桩基础长度,可以进一步降低对既有高速铁路桥梁沉降的影响；(4)理论计算结果与实际会有一定的差异,对于下穿高速铁路的工程,应建立完善的监测方案和监测方法,并制定监测控制指标和预警值,确保工程实施中和实施后高速铁路运营的安全.%Research purposes: As the foundation of the new building near the existing railway bridge will produce additional stress to the soil, it is inevitable to cause foundation deformation of the existing railway bridge. The Jinan west connecting track bridge of the newly - built Shijiazhuang - Jinan Passenger Dedicated Line needs to undern - pass the Yellow River south approach Bridge of the Beijing - Shanghai High - speed Railway. As the ballastless track is used for the Beijing - Shanghai high - speed Railway, it requires strict control of the settlement of the bridge substructure to ensure the safety of train running. Therefore, it is necessary to study the settlement influence on the Beijing - Shanghai High -speed Railway caused by under - passing of the Shijiazhuang - Jinan Passenger Dedicated Line's bridge. The Plaxis 3D finite element program was used to analyze the settlement influences on the bridge of the Beijing - Shanghai High - speed Railway when the solid bridge pier or frame bridge pier of the Shijiazhuang - Jinan Passenger Dedicated line under - passes for the purpose of determining the minimum impact on the structure and stabilizing the track alignment. Research conclusions: The analysis results illustrated that on consideration of the additional settlement of foundation caused by the newly building bridge ,the maximum unequal settlement of the adjacent solid pier structure of the existing Beijing -Shanghai High - speed Railway was 3. 2mm and the frame pier structure was 4, 3mm, and they were in the regulatory range of 5mm and feasible. It was recommended to use the solid pier structure because its additional impact was lesser than the others. In addition, it was proposed that the settlement influence on the existing high - speed railway bridge could be further reduced by extending the length of pile foundation of the new bridge properly and it also pointed out there was a variation between theoretical calculation and real data, so the perfect monitoring scheme, method, control value and early warning value would be established and improved to ensure the safe construction and safe operation of high - speed railway.
