基于Lamb波的CRTSⅡ型板式无砟轨道层间损伤检测方法

CRTSⅡSlab Ballastless Track Interlayer Damage Detection Method Based on Lamb Wave

CA砂浆层间损伤直接影响CRTSⅡ型板式无砟轨道的服役性能。通过建立刚性边界条件下Lamb波在CRTSⅡ型板式无砟轨道中传播的理论模型,研究了无砟轨道Lamb波的频散特性,确立对缺陷敏感的Lamb波模态以及在空气耦合方式下该模态的激励参数。通过实验室等比例模型试验对所提CA砂浆层间损伤空气耦合Lamb波检测方法进行验证。结果表明:当空气耦合超声探头中心激励频率为28 kHz、入射角3.5°时,可在CRTSⅡ型无砟轨道板中激励产生Lamb波A3模态,利用该模态可以进行无砟轨道层间损伤检测;随着CA砂浆层间脱空损伤尺寸增加,能量泄漏减少,接收的Lamb波A3模态能量增加,幅值增大,呈现线性变化规律;采用非接触式空气耦合Lamb波可实现CRTSⅡ型板式无砟轨道层间损伤的快速定量检测。

CA mortar interlayer damage directly affects the service performance of CRTSⅡslab ballastless track.The dispersion characteristics and excitation parameters of Lamb wave in ballastless track were studied by developing a theoretical model of Lamb wave propagation in CRTSⅡslab ballastless track with rigid boundary constrains.The Lamb wave mode sensitive to defects and the excitation parameters of the mode in the air coupling mode were established.The proposed air-coupling Lamb wave detection method for interlayer damage of CA mortar was verified through laboratory equal-scale model tests.The results show when the excitation center frequency of the air coupled ultrasonic probe is 28 kHz with the incident angle of 3.5°,the Lamb wave A3 mode can be stimulated in CRTSⅡslab ballastless track,which can detect the interlayer void damage of the ballastless track.With the increase of void damage size between CA mortar layers,the energy leakage decreases and the received Lamb wave's energy of A3 modal as well as the amplitude increase,showing a linear variation law.The use of non-contact and air-coupled Lamb wave can realize fast and quantitative detection of the interlayer damage of CRTSⅡslab ballastless track.