铁道建筑

依托张吉怀铁路（张家界—吉首—怀化）芙蓉镇酉水大桥，通过分离温度及列车长短期荷载效应，研究山区铁路非对称拱桥线形及温度作用规律。结果表明：主桥跨中测点竖向挠度整体呈正弦曲线特征，总体呈上拱快、下挠慢的特点，主梁上拱比环境温度滞后2.3 h；采用一阶差分法对温度长期及列车短期挠度进行趋势分离，长期挠度日变化幅值为29.47 mm，过车时刻下挠最大值为7.19 mm，采用高频设备测得过车时刻下挠幅值为7.75 mm，幅值比为1.07；主梁整体线形在08:00左右下挠最大，下挠幅值为-8.70 mm,17:00左右上拱最大，上拱幅值为20.95 mm，温度线形变化率为3.30 mm/℃。主梁线形在非对称拱拱顶附近呈竖斜向规律变化；主梁挠度年变化规律随季节更迭变化明显，采用线性回归分析法建立温度-挠度年变化数学模型，拟合相关系数在0.94左右，可为类似桥梁设计及工务运维平顺性分析提供参考；采用有限元模型进行温度效应分析，现场实测挠度均小于理论计算值，主桥运营期实际运行状态良好，满足理论设计要求。

Based on the Zhangjiajie-Jishou-Huaihua railway, the Youshui Bridge in Furong Town was used to study the alignment and temperature effect of asymmetric arch bridges on mountain railways by separating temperature and long-term and short-term load effects of trains. The results show that the vertical deflection of the mid-span measuring point of the main bridge exhibits a sinusoidal curve characteristic, with a fast upward arch and slow downward deflection. The upper arch of the main girder lags behind the ambient temperature by 2.3 h. The first-order difference method is used to separate the long-term and short-term deflection trends of the temperature. The daily variation amplitude of the long-term deflection is 29.47 mm, and the maximum downward deflection at the passing time is 7.19mm. The high-frequency equipment is used to measure the downward deflection amplitude at the passing time, which is 7.75 mm, with an amplitude ratio of about 1.07. The overall alignment of the main girder has the maximum downward deflection around 08:00, with a deflection amplitude of-8.70 mm. The maximum upward deflection is around 17:00, with an upward deflection amplitude of 20.95 mm. The temperature alignment change rate is 3.30 mm/℃. The main girder alignment changes vertically and diagonally near the asymmetric arch crown. The annual variation law of main girder deflection varies significantly with seasonal changes. A mathematical model of temperature deflection annual variation was established using linear regression analysis, and the fitting correlation coefficient was around 0.94, which can further provide reference for similar bridge design and smooth operation and maintenance analysis. The finite element model was used for temperature effect analysis, and the measured deflection on site was less than the theoretical calculation. The actual operating state of the main bridge during the operation period is good, meeting the theoretical design requirements.