动静态轨道不平顺评价差异及动态弦测法特性

中点弦测法能够有效控制影响行车安全性和舒适性的指定波段轨道不平顺，主要用于测量轨道静态不平顺，但其较低的测量效率制约着轨道“状态修”的发展. 针对上述问题，将轨道动态不平顺按中点弦测输出，分析动静态弦测值差异与弦长和不平顺波长的关联关系，提出能够评价轨道动态平顺性的动态弦测法，研究动态不平顺与静态不平顺间的映射关系. 研究结果表明:42 m和70 m动态高通滤波幅值分别与10 m弦和20 m弦测值变化规律相当；当不平顺波长大于70 m时，120 m动态高通滤波幅值与40 m弦测值变化规律基本对应；截止波长为42、70、120 m的轨道动态不平顺，分别与弦长为20、30 ~ 40、30 ~ 60 m的动态弦测波形相关性最优，对应的动态弦测法最大合理弦长分别为20、30、40 m，通过路基和简支梁区段实测数据验证了动态弦测法的适应性；在路基沉降区段，弦长为60 m时，静态弦测值明显朝负方向偏离动态弦测值的处所为沉降点，相邻两侧朝正方向偏离动态弦测值的处所为沉降区段起终点. 

Evaluation Difference of Dynamic and Static Track Irregularity and Characteristics of Dynamic Chord Measurement Method

The midpoint chord method can effectively control the track irregularity of the designated band that affects the driving safety and comfort. It is mainly used to measure the track static irregularity. However, its low measurement efficiency restricts the development of track ‘state-maintenance’. To solve the above problems, the track dynamic irregularity is output according to the midpoint chord. The correlation between the dynamic and static chord measured values with the chord length and the irregularity wavelength is analyzed. The dynamic track irregularity is outputed according to the midpoint chord measurement. A dynamic chord measurement method is proposed, that can evaluate the dynamic smoothness of the track, and studies the mapping relationship between dynamic irregularity and static irregularity. The results show that, the dynamic high-pass filter amplitudes of 42 m and 70 m are equivalent to the measured values of 10 m chord and 20 m chord respectively. When the irregularity wavelength is greater than 70 m, the 120 m dynamic high-pass filter amplitude basically corresponds to the variation law of 40 m chord measured value. The track dynamic irregularities with cut-off wavelengths of 42, 70 m and 120 m have the best correlation with the dynamic chord measurement waveforms with chord lengths of 20, 30–40 m and 30–60 m respectively. The maximum reasonable chord lengths of the dynamic chord measurement method are 20, 30 m and 40 m respectively. The adaptability of the dynamic chord measurement method has been verified by the measured data of subgrade and simply supported beam sections. In the subgrade settlement section, when the chord length is 60 m, the place where the static chord measurement value deviates significantly from the dynamic chord measurement value in the negative direction is the settlement point, and the places where the adjacent two sides deviate from the dynamic chord measurement value in the positive direction are the beginning and end of the settlement section.