高速铁路混凝土桥梁徐变变形计算分析及控制措施研究

Research on Calculation Method and Control Measure of Creep Deformation of Concrete Bridge on High-speed Railway

预应力混凝土的后期徐变变形会引起桥梁的上拱和下挠,造成轨道不平顺。在分析研究桥梁后期徐变变形对无砟轨道平顺性影响的基础上,提出理论徐变变形修正系数的计算方法以及无砟轨道施工断面点计算时提前预留徐变效应引起的垂直位移量的工程控制措施。通过对京沪高速铁路3个预制梁场修正系数的研究结果表明,32.6 m直线预制梁终张拉后60～180 d某些时间节点的修正系数仅为0.5,修正前后徐变变形量差异最大达4.6 mm;理论徐变经修正系数修正后能够提高其与实际变形的接近程度;在无砟轨道各施工阶段断面点计算时提前预留徐变效应引起的垂直位移量能够减少后期徐变变形对无砟轨道铺设后平顺性的影响。

Creep deformation in later period of pre-stressed concrete will cause hogging and sagging of a bridge, then cause irregularity of the track. To solve this problem, after analyzing and researching the effect on the regularity property of ballastless track caused by the later-period creep, a new computational method was proposed in which the theoretic creep deformation should be assisted by a correction coefficients; also a new control measure was put forward： when calculating the constructed cross-section points, a vertical displacement should be reserved in advance to offset the creep effect. Meanwhile, a research on this correction coefficient was carried out at three girder-prefabrication yards on Beijing- Shanghai High-speed Railway. The results show that, by the time of 60-180 d after girder＇s final tension, at some time point the correction coefficient of straight preeast girder of 32.6 m in length is only 0.5, and the maximum difference of creep deformation is up to 4.6 mm before and after the correction. Finally, the author comes to the conclusion that, the theoretical creep deformation with this correction coefficient can be closer to the actual creep deformation than that of without this correction coefficient; and the influence on the regularity property of ballastless track caused by later-period creep of concrete can be weakened effectively by reserving the vertical displacement in advance when calculating every cross-section point of every construction stage.