Research On Dynamic Characteristics And Stiffness Optimization Of 250km/h High-Speed Railway Ballasted Track

High-speed railway is an important business card for the rapid development of science and technology in China.The main track structures used in China’s high-speed railway are ballasted track and ballastless track.At present,most of the main high-speed railway networks are built in the form of ballastless track.In the future development,the construction of China’s high-speed railway network is bound to be more intensive,including the increase of high-speed railway connections between intercity high-speed railways and prefecture-level cities.Therefore,the construction of high-speed railways will continue to increase,and ballastless tracks will gradually become prominent due to their high construction costs,high construction difficulties,and difficult maintenance.In contrast,ballasted track will become the main track structure of high-speed railway construction in the future because of its relatively low construction cost,low construction difficulty and low maintenance difficulty.Therefore,in order to ensure the safety and stability of the train running at high speed on the ballasted track,it is necessary to study the dynamic characteristics and stiffness optimization of the high-speed railway ballasted track.At the same time,it also provides a corresponding reference for the high-speed and safe running of the train on the ballasted track.In this paper,the vehicle-track coupling dynamics theory is taken as the basic theory,and the vehicle-track space coupling dynamics simulation model of high-speed railway ballasted track is established by using multi-body dynamics simulation software,and the track geometric irregularity is added as the model excitation.The main work of this paper is as follows:(1)Consult the relevant literature,understand the development history and process of high-speed railway at home and abroad,and understand the research history of wheel-rail dynamics,and clarify the research significance and research methods of this paper.(2)Taking the vehicle-track coupling dynamics as the theoretical basis,the appropriate track irregularity excitation is selected.Combined with the vehicle dynamic parameters and ballast track parameters of CRH2 vehicle,the vehicle-track spatial coupling dynamics model is established by using multi-body dynamics simulation software,and the model is verified.(3)The critical value range of track structure stiffness in static angle is obtained by analyzing and calculating the static angle of vehicle-track coupling dynamic system.(4)The dynamic characteristics of the vehicle-track power system are analyzed by changing the stiffness of the fastener and the stiffness of the track bed respectively.(5)Considering the matching effect of fastener stiffness and ballast stiffness,the sensitivity coefficient method is used to optimize the stiffness of vehicle-track coupling dynamic system,and the optimal values of fastener stiffness and ballast stiffness are obtained.After completing the above work,the following results are obtained:(1)Through the static analysis,the critical range of the stiffness of the track structure in this paper can be obtained:The value range of the total stiffness K of the track is between 63.337～269.928 k N/mm;The elastic modulus u of the rail foundation ranges from 34.646～239.396N/mm~2;The range of rail support stiffness D is 20.788～143.638 k N/mm.(2)The sample distribution of wheel-rail vertical force under irregularity excitation shows a normal distribution,and the vertical force has the highest frequency in the distribution range near the static wheel load.The sample distribution of wheel-rail lateral force is similar to normal distribution,but its frequency diagram is not symmetrical.The image of lateral force less than the highest frequency is slower,and the image of lateral force greater than the highest frequency is steeper.(3)The mean values of wheel-rail vertical force and lateral force remain unchanged with the increase of fastener stiffness or ballast stiffness,and the mean value of wheel-rail vertical force is about static wheel load.In addition,the sample distribution of vertical force and lateral force will be more and more dispersed.The change of lateral force is less than that of vertical force,and the dynamic influence of overall fastener stiffness is greater than that of ballast stiffness.(4)With the increase of fastener stiffness or ballast stiffness,the safety and stability of vehicle operation are reduced.Similarly,the influence of fastener stiffness is greater than that of ballast stiffness.(5)By using the sensitivity coefficient method,it can be known that the sensitivity of the vertical displacement of the rail to the stiffness of the fastener and the stiffness of the track bed is relatively high,and the sensitivity of the vertical force of the wheel and rail to the stiffness of the fastener and the stiffness of the track bed is relatively low.(6)After using the sensitivity coefficient analysis,it is found that the optimal stiffness ratioηof the fastener to the track bed will increase with the increase of the total stiffness K of the track.In this paper,the optimal stiffness ratio is about 1:2,and the optimal total stiffness is about 117.256 k N/mm,so that the optimal fastener stiffness is about 71.7 k N/mm,and the optimal ballast stiffness is about 138.4 k N/mm.