Study on the Formation Mechanism for High Rail Corrugation

This research employed a tracking investigation and numerical study to examine the initiation of high rail corrugation. Beginning with the trial operation of Metro Line 6 in Chengdu, China, we conducted a follow-up investigation for two and a half years that recorded the rail surface wear morphology of a 600 m radius curved track. The field observation results show that high rail corrugation occurred 12-17 months after the subway was officially put into operation, whereas the low rail of the same track did not show any corrugation. The distribution of high rail corrugation was discontinuous. Due to wear, the profiles of the rails and wheels changed. Two points of contact may occur between the leading outer wheel and high rail, with one contact point at the gauge corner and the other in the vicinity of the railhead (hereafter referred to as two-point contact). We developed a finite element model that used the measured worn profiles to predict the self-excited frictional vibrations of a leading wheelset–rails system under the condition of two-point contact. We predicted the occurrence trend of self-excited frictional vibrations via the complex eigenvalue analysis. The simulation results show that, in the condition of two-point contact, the self-excited frictional oscillation produced at an outer wheel–high rail interface can induce high rail corrugation. The use of straight or double S-shaped web plate wheels and an increase in railpad damping can help to reduce high rail corrugation.