Research On The Evolution Mechanism Of Rail Corrugation On Tight Curves In Heavy-haul Railway

Rail corrugation is one of the most typical diseases of Heavy-haul railway.With the increase of axle load and operation volume of Heavy-haul railway,rail corrugation is becoming more and more serious.According to the investigation,rail corrugation is very common,and there are serious rail corrugation on heavy-haul railways such as Daqin Railway,Shanxi Central and Southern Railway and Shenhua Railway.At the same time,about 40%of the curve areas will sprout rail corrugation,especially in small radius curve areas,rail corrugation not only appears early,but also develops rapidly,which seriously affects the economic benefits and operational safety of heavy-haul railway.Combining with the problem of small radius curve rail corrugation of heavy-haul railway in China,relying on the research topic of Shenshuo heavy-haul railway rail corrugation,based on field investigation and testing,theoretical research is carried out by numerical analysis and other methods,and the development and evolution law of single side rail corrugation of small radius curve of heavy-haul railway is analyzed.The main research work and results are as follows:(1)Based on the domestic and foreign research data and research results on the development of heavy-haul railway,the causes of rail corrugation and theoretical measures,the experimental methods,theoretical basis,modeling methods and evaluation indicators are summarized.(2)A long-term investigation,testing and statistical analysis were carried out for rail corrugation on heavy-haul railway.Specific contents include:types of rail corrugation,characteristics and regularities of wavelength and trough distribution,differences in location and dynamic test indexes of rail corrugation,relationship between rail corrugation and line conditions,traffic volume,locomotive types,and development speed and evolution law of rail corrugation after its appearance.The results show that the rail corrugation wavelength of heavy-haul railway is about 200 mm,which belongs to the typical medium wavelength corrugation,and accompanied by obvious plastic rheological characteristics.Moreover,the interaction between wheel and rail in curve section is stronger than that in straight section,and the stress state of inner and outer rails is quite different.In the early stage of rail corrugation,the initial irregularities such as fish scale and peeling off blocks occur,and then the obvious rail corrugation phenomenon first appears on one side of the rail and gradually transfers to the other side of the rail.(3)Based on the theory of friction self-excited vibration of wheel-rail system induced by saturated creep force,the finite element model of wheel-rail system is established by commercial finite element software ABAQUS,aiming at the characteristics of actual heavy-haul Railway vehicle and wheel-rail tread on site.The complex eigenvalue analysis and the correlation analysis of factors such as fastener stiffness,friction coefficient and superelevation are carried out.The results show that increasing the vertical and lateral stiffness of fasteners properly and controlling the friction coefficient of wheel and rail below 0.4 can effectively reduce the possibility of unstable vibration of wheel-rail system and thus restrain the development of rail corrugation.At the same time,excessive superelevation will directly lead to unstable friction self-excited vibration of wheel-rail system at the inner wheel-inner rail,while under-superelevation will lead to unstable friction self-excited vibration of wheel-rail system at the outer wheel-outer rail.The conclusion further explains the reason why the rail corrugation always occurs first on one side of the rail in the small radius curve section of heavy haul-railway.(4)Through the transient dynamic analysis of wheel-rail system,the evolution process of rail corrugation and its transmission is simulated.The results show that the disturbance of rail corrugation will lead to unstable vibration of wheel-rail system.The unstable vibration of wheel-rail on the one side of rail corrugation will gradually transfer to the non-rail corrugation side,while the vertical unstable vibration will gradually transfer to the lateral vibration,and further amplify the dynamic response of wheel-rail,so that the cycle reciprocating will cause the rail corrugation to transfer gradually from one side to the other side,and deteriorate continuously,and develop rapidly.The conclusion further confirms the viewpoint that unreasonable superelevation results in friction self-excited vibration induced by wheel-rail creep force saturation.(5)Based on the actual requirement of field specific grinding,combined with the measured rail profile change data of MINIPROF,wheel-rail dynamics analysis is carried out by means of SIMPACK,and dynamic analysis is carried out by taking account of track irregularity,small radius curve and other factors.The wheel-rail contact change,creep behavior change and motion after grinding the rail on one side are studied from a dynamic point of view when the rail is first corrugated.Differences in mechanical behavior.The results show that when obvious rail corrugation occurs on one side of the rail,it is suggested that specific polishing on one side of the rail be carried out to inhibit the development and transmission of rail rail corrugation and improve the contact behavior and stress condition between wheel and rail.