32 m简支梁顶梁作业对有砟轨道无缝线路状态的影响

Influence of 32 m Simply Supported Girder Jacking Operation on State of Ballasted Track Continuously Welded Rail

以32 m简支梁为研究对象,测试两端支座顶升、单边支座顶升、单墩支座顶升三种工况下的钢轨应变,计算分析顶升过程中钢轨纵向附加力和落梁后钢轨锁定轨温的变化规律;应用有限元软件建立桥上无缝线路梁轨相互作用模型,采用双线性阻力模型计算三种顶升工况下的钢轨附加力,并与现场测试结果进行对比。结果表明:落梁后钢轨内部存在残余附加力,引起钢轨锁定轨温改变,最大改变量为0.36℃,小于规范规定的5℃限值,不需要进行应力放散;三种顶升工况下,顶梁作业对钢轨纵向附加力影响范围均在顶升桥梁的相邻一跨简支梁以内,且产生的钢轨纵向附加力峰值均位于顶升位置和梁端位置;两端支座顶升方案对无缝线路影响最小,建议桥梁支座更换施工时采用该方案。

Taking a 32 m simply supported girder as the research object,the rail strains under three working conditions,namely,jacking at both ends of the support,jacking at one side of the support,and jacking at one pier support,were tested,and the longitudinal additional force of the rail during the jacking process and the change rule of the rail locked rail temperature after the lowering of girder were calculated and analyzed.The girder rail interaction model of continuously welded rail(CWR) on bridge was established by using finite element software.The bilinear resistance model was used to calculate the additional rail force under three jacking conditions,and the results were compared with the field test results.The results show that there is residual additional force in the rail after lowering of girder,which causes the change of the locked rail temperature of the rail.The maximum change is 0.36 ℃,which is less than the limit value of 5 ℃ specified in the specification.No stress release is required.Under the three jacking conditions,the influence range of the jacking operation on the longitudinal additional force of the rail is within the adjacent span simply supported girder of the jacking bridge,and the peak value of the longitudinal additional force of the rail is located at the jacking position and the girder end position.The jacking scheme of bearings at both ends has the least impact on the CWR.It is recommended to adopt this scheme when replacing bridge bearings.