Research On Dynamic Coefficient And Stiffness Optimization Of Heavy-haul Railway

Heavy-haul railway track structure needs to bear the action of train load and temperature load repeatedly.Multiple load will cause damage to track structure.With the increase of axle load and speed of freight cars,wheel-rail interaction will intensify,and the service life of track structure will be shortened.Therefore,it is of great significance to study the statistical law of interaction force between heavy axle load freight car and track structure.Based on this,the dynamic coefficients and fatigue loads of heavy haul track structure are put forward,which can provide corresponding reference for the design,maintenance and repair of heavy haul railway track.On the basis of vehicle-track coupling dynamics,this paper establishes the coupling model of heavy haul truck and ballasted track,calculates the wheel-rail forces under different driving conditions and track parameters,studies the wheel-rail force distribution under different working conditions by means of mathematical statistics,and analyses the dynamic response of vehicle and track under different working conditions,and obtains ballasted heavy haul track.Finally,the track structure under 32.5t axle load is optimized with the objective function of minimizing the comprehensive dynamic response of the track.The results show that:(1)The vertical force of wheel and rail calculated by random irregularity as excitation conforms to the normal distribution,while the lateral force of wheel and rail does not conform to the normal distribution.Its density function curve is similar to the normal distribution curve,but the one side is gentle and the other side is steep,which is not symmetrical as the two sides of the normal distribution.(2)With the increase of vehicle speed,the mean value of wheel-rail vertical force is unchanged,the standard deviation and coefficient of variation are increased,and the mean value of lateral force,standard deviation and coefficient of variation are increased;with the increase of vehicle axle load,the mean value of wheel-rail vertical force increases,the standard deviation is unchanged,the coefficient of variation decreases,the mean value of lateral force increases,the standard deviation and coefficient of variation do not change significantly;with the stiffness of fastener and the stiffness of ballast bed,the change is arbitrary.The mean values of vertical force and transverse force are unchanged,and the standard deviation and coefficient of variation are increased with the increase of the number.(3)The dynamic coefficients of transverse force and vertical force increase with the increase of driving speed and decrease with the increase of axle load.The fatigue checking load of vertical force increases with the increase of driving speed and axle load.The simple fatigue loading of transverse force increases with the increase of driving speed,and the change of axle load has little effect on the fatigue checking load of transverse force.(4)According to the law of wheel-rail force distribution under different working conditions,this paper suggests that when the design speed is 80 km/h,the vertical force dynamic coefficient is 1.55 and the lateral force dynamic coefficient is 0.25;when the design speed is 100 km/h,the vertical force dynamic coefficient is 1.60 and the lateral force dynamic coefficient is 0.30.(5)Sleeper displacement is the most sensitive to the stiffness ratio.The other dynamic parameters are sleeper acceleration,rail displacement,sleeper pressure and rail acceleration,and the least sensitive is wheel-rail force.(6)Based on the sensitivity coefficient method and the minimum comprehensive dynamic response of track structure,it is concluded that the track stiffness value under 32.5t axle load freight car should be 100 kN/mm to 135 kN/mm,and the stiffness ratio of fastener ballast bed should be 0.65.