线路纵向阻力形式对桥上无缝线路计算影响

为了研究线路纵向阻力形式对桥上无缝线路纵向力的影响,基于梁轨相互作用原理,采用有限元方法建立了线-桥-墩一体化计算模型,以多跨简支梁为例,分析了常阻力、双线性和幂指数型等不同形式的线路阻力对计算桥上无缝线路时的影响。计算结果表明:常量阻力下计算得到的钢轨伸缩力较双线性及幂指数型阻力要小,且随温度跨度的增加双线性和幂指数型计算结果越来越接近,而常量阻力与两者差别逐渐增大;计算钢轨制动力时,常量阻力计算结果要小得多,且梁轨相对位移较大,已超出我国检算标准;不同钢轨降温幅度下,双线性和幂指数型阻力计算的钢轨断缝值基本相同,但却远小于常量阻力,且钢轨降温幅度越大,差别越大。由此可知,应重视线路阻力形式的选取,尽量由实际测试数据进行拟合,使其能模拟真实的现场情况。

Influence of Track Longitudinal Resistance Form on the Calculation of Continuous Welded Rail Sited on Bridge

There are influences on the calculation of longitudinal force of continuous welded rail sited on a bridge,which are caused by different track longitudinal resistance forms. In order to ascertain the influences,by using finite element method and based on the interaction principle between girder and track,the integrated calculation model of track-bridge-pier was established. And by taking an multi-span simply-supported girder as the example,the influences on continuous welded rail's calculation were analyzed,which were caused by different track resistances forms such as the ordinary resistance,bilinear resistance,power-exponent resistance and so on. The calculation results show that: the rail expansion force calculated by ordinary resistance is smaller than that by bilinear resistance or by power-exponent resistances,and then when the temperature span length increases,the results calculated respectively by bilinear resistance and power-exponent resistance will become closer and closer with each other,while the difference between the results calculated by ordinary resistance and by the two other forms will increase gradually. Furthermore,for the calculation of rail braking,the result calculated by ordinary resistance is much smaller; while the relative displacement between girder and track is bigger,exceeding the checking standard in China. In addition,under the different magnitudes of temperature lowering of steel rail,the rail gaps calculated respectively by bilinear resistance and by power-exponent resistance are basically the same,but far less than that by ordinary resistance; and the greater the magnitude of steel rail temperature lowering is,the greater the difference becomes. Therefore,it is suggested that the selection of track resistance forms should be paid attention to; and these data measured from the actual field should be adopted as much as possible for the data fitting so as to truly simulate the field situation.