基于脉冲激励下钢轨振动响应的扣件失效识别方法

FAILURE IDENTIFICATION METHOD OF FASTENING SYSTEM BASED ON RAIL RESPONSE UNDER PULSE EXCITATION

针对高速铁路无砟轨道扣件失效的检测问题,提出了脉冲激励下钢轨振动响应的扣件失效识别算法。利用实验室1∶1实尺模型,通过人工移除扣件弹条的方式模拟扣件失效,分别测试得到脉冲激励下钢轨在扣件良好及失效状态下的时域振动响应,利用快速傅里叶变换及倍频程分析得到钢轨的振动加速度级。将扣件良好及失效状态下钢轨振动加速度振级差值和特征频带占比作为判断扣件失效的评价指标,进一步研究了频带划分方式、振动加速度振级差阈值、特征频带占比阈值对于识别准确率的影响规律,最后提出了针对扣件失效的识别算法与敏感参数选取,结合实验室和京沈高铁正线现场的测试结果对算法的可靠性进行了验证。在此基础上,进一步研究了测点安装位置、邻近非目标扣件失效以及人为操作误差对于识别准确率的影响规律。结果表明:该文提出的扣件失效识别程序在扣件单侧失效条件下的准确率可达100%;在目标扣件两侧的相邻扣件存在失效时,目标扣件的识别准确率仍可达到100%;当测点位于扣件所在断面的钢轨轨腰及轨底外侧时识别准确率在95%以上;沿线路方向上,以扣件中心线为基准,当激励点位置与基准位置的偏差小于6 cm、测点位置与基准位置偏差不大于6 cm时程序识别准确率在95%以上。

Focusing on the failure detection of high-speed railway ballastless track fastening system,it proposed a failure identification algorithm based on the rail vibration response under pulse excitation.The failure of the fastening system was simulated by removing the elastic bar manually.The time-domain vibration responses of the rail with both functional and failed fasteners under pulse excitation were measured with the 1∶1 full-scale model in the laboratory.By carrying out the Fast Fourier transform and the octave analysis,the vibration acceleration levels of the rail under functioning and failed fastener conditions were obtained.By adopting the rail acceleration level difference and the characteristic frequency band percentage with and without failed fasteners as the evaluation indicator,the influence of frequency band division,vibration acceleration difference threshold and characteristic frequency band percentage threshold on the identification accuracy were further studied.The fastening system failure identification algorithm was proposed and the sensitive parameters for the failure of fasteners were selected.Together with the laboratory test results and field tests in Beijing-Shenyang high-speed railway,the effectiveness of the algorithm was verified.On this basis,the influence of the fixing position of the measuring accelerometer,the existence of non-target failure fasteners in the near-by span,and the human operation error on the recognition accuracy were further studied.The results show that the accuracy of the fastener failure identification algorithm proposed in this paper can reach 100%under the condition of one-sided failure of the fastener.When fasteners'failures on near-by span exist,the detection accuracy rate of the target fastener failure is also 100%.When the measuring accelerometers are located on the rail web and rail bottom where the target fastener is,the detection accuracy rate is above 95%.By taking the center line of the fastener as the reference,the detection accuracy rate is above 95%when the deviation between the excitation position and the reference position is less than 6 cm,or the deviation between the accelerometer fixing position and the reference position is less than 6 cm along the line operation direction.