中文摘要：

基于东南地区某32m简支梁-CRTS Ⅰ型双块式无砟轨道2a的实测温度数据,提出基于GPD模型的温度梯度尾部数据拟合方法,重点研究了箱梁-轨道系统竖向温度梯度分布规律,并对箱梁-轨道系统的竖向温度梯度尾部数据极值进行了估计,提出现场实测最大温度梯度模式与对应估计100a重现期的温度梯度拟合模式.研究表明：GPD模型可对尾部极值温度数据进行很好地拟合,预估不同概率需求的温度梯度荷载值;箱梁-轨道系统截面Ⅰ与截面Ⅱ日温度梯度变化特征基本一致,于11：00～21：00前后出现正温度梯度,16：00达到最大,于01：00～9：00前后出现负温度梯度,7：00达到最大;采用GPD模型计算对应100a重现期估计值,截面Ⅰ最大正温差的实测值与估计值分别为15.2℃和23.36℃,截面Ⅱ为17.4℃和24.4℃,采用不同形式对箱梁-轨道系统竖向梯度实测正负温度梯度最大值与100a一遇估计值进行拟合,拟合相关系数的平方均在0.98以上,可为规范修正与桥梁设计提供参考.

英文摘要：

Through the temperature field data of CRTS Ⅰ twin-block ballastless track with 32 msimple supported beam bridge for 2 a,the vertical distribution of temperature gradient was analyzed in detail and the fitting method of temperature gradient tail data based on generalized pareto distribution（GPD）model was proposed to estimate the extreme value of vertical temperature gradient.The maximum temperature gradient model and the corresponding temperature gradient fitting model for 100 a return period were presented.The analysis results reveal that the GPD model can be used to fit the extreme temperature data of tail,estimating the temperature gradient load value of different probability demand.The variation characteristics of temperature gradient between section Ⅰ and section Ⅱ of box girder-track system are basically the same.The positive temperature gradient appeares around 11：00 to 21：00,reaching the maximum at 16：00,and the negative temperature gradient appeares around 01：00 to 9：00,reaching the maximum at 7：00.The estimated value of corresponding 100 areturn period can be calculated by using GPD model.The measured and estimated values of the maximum positive temperature difference of the section Ⅰ are 15.2℃ and 23.36℃respectively,and that of the section Ⅱ are 17.4℃ and 24.4℃.The measured maximum values and the estimated values of the vertical gradient were fitted with different forms.The correlation coefficients of the fitting forms are morethan 0.98,which are used for the engineering application and reference.