The Study On Wheel-rail Contact Characteristics And Rails Profile Optimization In Switch Area Of High-speed Railway

As an important part and key equipment of railway lines,turnouts integrate the weak links and technical features of track structures.When a train passes through turnout,the rails are contact with the wheels directly,the geometric state of the rail will directly affect the stability and safety of the train.If the profile of the rails in turnout area is poor,the contact relationship among wheels and rails will be mismatched,aggravate the mutual wear between wheels and rails,and even cause serious train derailment accidents.As an important antifriction measure,the optimization of wheel/rail profile is always a hot issue in the research of track structure.It is great significance to the design of new lines and maintenance of existing lines that by optimizing and improving the profile of abraded rails and using the theoretically calculated optimal profile as the target profile to guide rail grinding on site.Based on the comprehensive analysis of current status of wheel-rail contact and rail profile optimization research in turnout area at home and abroad,studied the wheel-rail contact characteristics and the shape optimization about rail profile of high-speed railway with the wheel-rail contact theory and vehicle-turnout coupling dynamics theory.The main research work and results of this article are as follows:(1)According to the structural composition and characteristics of the No.18 single turnout of the 60kg/m steel rail of high-speed railway in China,making the standard profile of rails in the switch area and the wear profile measured in the field as examples,the vehicle-turnout dynamic analysis model under two profiles is established using UM software with the wheel-rail contact theory and the vehicle-turnout coupling dynamics theory.And then verified the correctness of the model established in this paper by compared with the existing research results.(2)Based on the established vehicle-turnout dynamics analysis model,according to standard profiles and wear profiles,compared and analyzed the dynamic characteristics of wheel-rail contact when a train passes through the turnout at high speed.The results show that,compared with the standard profile,the calculation results of the derailment coefficient and wheel load reduction ratio of the wear profile have increased by 30.27% and 70.51% respectively,and the lateral and vertical vibration acceleration of the vehicle body increased by 50% and 57.69%,the safety and stability of trains passing through switch are reduced,so the engineering department should strengthen the grinding of the rails in the turnout area.(3)Based on the principle that the difference of the first derivative of the profile of the wheel-rail profile is the smallest,constructed the optimized objective function of the wear profile,and completed the optimized design of the wear profile.Then,according to the abrasion profile and the optimized profile,compared and analyzed the dynamic characteristics of trains passing through turnouts at a high speed.The results show that,compared with the wear profile,the derailment coefficient and wheel load reduction rate of optimized profile conditions have been reduced by 8.5% and 15.4%,and the lateral and vertical vibration acceleration of the car body have been reduced by 33.3% and 28.4%.The safety and stability of train crossings have been effectively improved,and the correctness of the rail wear profile optimization method in the turnout area of this paper has been verified.At the same time,it also provides theoretical support for the maintenance and polishing of the rail profile of existing turnouts in China.(4)Based on the wheel-rail contact relationship in the turnout area and the dynamic theory of the wheel-rail system,taking the movable turnout of No.18 high-speed turnout as an object,studied and analyzed the influence of the wing-rail heightening value on the dynamic characteristics when trains passing through turnout at a high speed.The results show that,by setting a reasonable wing rail heightening value,the problem of the vertical position of the wheel center of mass can be effectively solved,which is beneficial to improving the stability of train crossings and passenger comfort.Compared with the non-height design,after the wing rail heightening design,the vertical wheel-rail force and load reduction ratio of the first wheel of the train were reduced by 18.16% and 35.8%,respectively;the vertical vibration acceleration of the wheelset and vehicle body reduced 48.1% and 34.7%,respectively,the vertical vibration characteristics of trains passing through forks have been effectively improved.The research results can provide theoretical reference for the structural optimization design of movable turnouts on railway lines in China.