Dynamic Analysis Of The Formation Mechanism Of Rail Corrugation On Subway Vibration Damping Fastener Track

Rail corrugation is a frequently occurring rail disease in the area where the vibrationdamping track is laid in the subway,which seriously affects the safety and ride comfort of the wheel-rail system.The research on rail corrugation has been going on for hundreds of years,but there is still no unified conclusion about its cause.Vibration damping by fasteners is more convenient and economical than damping methods such as sleeper damping and track bed damping,so the vibration damping fastener tracks are laid at a higher rate in subways in various cities.The different types of vibration damping fastener tracks almost all have too short wavelength rail wave grinding phenomenon,and the straight line section and the curved lot are distributed,of which the curve section is especially the small radius curve lot with high frequency..In this thesis,the causes and parameter effects of rail corrugation that occur on the subway GJ-III vibration damping fastener track are used as the research object,The main research work is as follows:(1)Briefly describes the development status of urban rail transit in my country,and introduces the research status of rail corrugation that occurs frequently in urban rail transit,mainly from the classification of rail corrugation,the causes of rail corrugation,the influencing factors of rail corrugation,the theoretical analysis model and the research situation of subway rail corrugation are discussed in five aspects.(2)A linear numerical analysis model of rail corrugation in frequency domain is established.The model mainly includes the wheelset velocity impedance solution module at different wheelsets under the mutual influence of the front and rear wheelsets,the track velocity impedance solution module at different wheelsets under the mutual influence of the front and rear wheelsets,and the rail corrugation growth rate solution module.The correctness of the model is verified by comparing with the literature results.(3)Using the frequency domain linear numerical analysis model of rail corrugation,the causes of rail corrugation in the straight section of the GJ-Ⅲ vibration damping fastener track are analyzed.The influence of key parameters such as vehicle load,wheelset mass,vertical stiffness and damping of primary suspension,vertical stiffness and damping of fasteners on rail corrugation in straight sections is analyzed.The results show that the main reason for rail corrugation with wavelengths of 30-40 mm in the straight section is that the rail vibration waves excited by adjacent wheel sets interfere with each other,which changes the rail vibration characteristics,and then affects the rail corrugation growth rate.By increasing the wheelbase of the vehicle,the growth rate of rail corrugation can be effectively reduced,and the wavelength of rail corrugation can be increased;by increasing the damping of the fastener,the growth rate of rail corrugation can be effectively reduced.(4)A vehicle–track coupling dynamic model is established considering wheelset flexibility and rail longitudinal vibration.Using this model,the causes of rail corrugation in small radius curved sections are studied from the perspective of wheel–rail vibration characteristics,and the correlation between the inherent dynamic characteristics of wheelset and track and rail corrugation is analyzed.Then the influence analysis of curve superelevation,wheel-rail friction coefficient,rail bottom slope,curve radius and fastener parameters on rail corrugation is discussed.The results show that the main reason for the corrugation of the rail with a wavelength of 30-40 mm in the small radius curve section is the saturation phenomenon of the creep force between the wheel and rail at the inner rail of the guide wheel pair,and the self-excited vibration of the wheel-rail friction is induced.Under random irregularity excitation or pulse excitation,the wheel–rail vibration amplitude is more prominent at the passing frequency of rail corrugation.By appropriately reducing the superelevation of the curve,reducing the wheel-rail friction coefficient,taking the value of the rail bottom slope to 1/40-1/30,and increasing the vertical stiffness of the fastener and the damping of the fastener,the development rate of rail corrugation can be reduced,and increasing the radius of the curve can improve the adhesion characteristics between the wheel and rail,and effectively reduce the possibility of saturation of the creep force between the wheel and rail.