Cause Analysis of Rail Corrugation in Metro Lines Based on System Vibration Characteristics

The mechanism of rail corrugation remains unclear, and the research methods require improvement. The vibration characteristics represent the system's external manifestations, but a comprehensive analysis is still lacking. Taking the vibration characteristics of the wheel-rail system as a starting point, this study investigates the formation mechanisms of rail corrugation on measured metro lines. The line sections included both steel spring floating slab tracks and long sleeper embedded tracks. First, the wavelength and frequency attributes of rail corrugation were obtained through field measurements. Then, referencing line conditions, three-dimensional finite element numerical models were established, frequency response calculations were performed, and the relationship between the vibration responses of the wheel-rail system and rail corrugation was analyzed. Finally, a parameter sensitivity analysis of the wheel-rail system was conducted to control the further development of rail corrugation. The results show distinct corrugation phenomena on both inner and outer rails in the measured sections. The characteristic wavelengths of inner and outer rail corrugation on the steel spring floating slab track are 34 mm and 59 mm, respectively,and the characteristic wavelengths of inner and outer rail corrugation on the long sleeper embedded track are 46 mm and 47 mm, respectively. The frequency response analysis indicates that the numerical results exhibit eigenfrequencies close to the passing frequencies of the measured corrugations. The formation mechanism of inner rail corrugation on the steel spring floating slab track is attributed to the third-order bending vibration of the wheelset,which leads to the generation of inner rail corrugation. In contrast, the formation mechanism of outer rail corrugation is attributed to the lateral bending vibration of the outer rail. For the long sleeper embedded track, inner rail corrugation is generated by the lateral bending vibration of the inner rail, while outer rail corrugation results from the lateral bending vibration of the outer rail. Appropriate adjustments to the fastener's vertical and lateral stiffness, as well as the steel spring's vertical and lateral stiffness, can shift the rail corrugation eigenfrequencies, thereby inhibiting the development of corrugation with the original wavelength. Changes in other parameters have no effect on the rail corrugation eigenfrequencies and only influence the development speed of corrugation with the original wavelength. This research effectively elucidates the cause of rail corrugation from the system vibration perspective and provides a valuable complement to the corrugation analysis method.