中文摘要：

研究目的：为得到高速铁路过渡段处钢轨温度沿纵向分布规律以及钢轨纵向位移变化特征,以合福高铁某桥隧过渡段为研究对象,对钢轨温度和纵向变形进行连续监测,以期为过渡段处无缝线路的稳定性研究提供参考。研究结论：（1）隧道洞口20 m范围内将形成轨温过渡段,局部最大温度梯度可达6.9℃/m,远大于温度梯度按线性分布计算所得的1.55℃/m;（2）过渡段处钢轨随着日温差的变化,其纵向位移变化显著,最大日轨温差为34.9℃,最大日变化量为1.6 mm;（3）过渡段处钢轨纵向位移呈现由桥梁向着隧道方向线性累积增加的趋势,最大累积变形量为2 mm;通车后累积变形速率为0.016 9 mm/d,大于通车前的0.014 7 mm/d;（4）基于最小二乘法建立了轨温过渡段钢轨温度沿线分布模式,以及钢轨日温差与钢轨纵向位移日变化量预估模型,得出：拟合精度较高,回归模型可靠;（5）本研究结论可为高速铁路无砟轨道桥隧过渡段钢轨温度力和纵向爬行提供研究基础。

英文摘要：

Research purposes： In order to obtain longitudinal distribution law of rail temperature and characteristics of rail longitudinal displacement at the transitions for high - speed railway, a transition between bridge and tunnel in Hefei - Fuzhou railway line was taken as research object and the rail temperature and longitudinal deformation was monitored continuously, to provide the reference for the stability research of jointless track at the transition section. Research conclusions： （ 1 ） Transition section of rail temperature will form in the range of 20 m around tunnel portal and local maximum temperature gradient will reach 6.9 ℃/m, which is far more than 1.55 ℃/m calculated according to the linear distribution of temperature gradient. （2） The rail longitudinal displacement at transition section varies obviously with the change of daily temperature difference. The maximum daily temperature difference is 34.9 ℃ and the maximum daily variation is 1.6 ram. （3） At the transition section, the rail longitudinal displacement has the trend to increase cumulatively and linearly, the maximum accumulation is 2 mm. The cumulative deformation rate is 0.016 9 mm/day after the line was open to traffic, which is faster than 0. 0147 mm/day before the line was open to traffic. （4） Based on least -squares method, the distribution mode of rail temperature along the line in the area of transition section of rail temperature and the prediction model of rail daily temperature difference - daily variation of longitudinal displacementwere established. The fitting accuracy is relatively high and the regression model is reliable. （5） The research results provide research foundation for rail temperature force and longitudinal creep at the transition between bridge and tunnel in ballastless track for high -speed railway.