Analysis Of Vertical Vibration Characteristics Of Railway Ballasted Track Bed

The conventional ballasted track employs the ballast track bed.Based on its low cost,easy maintenance,easy drainage,benign vibration and noise reduction performance,it is widely utilized in ordinary passenger and freight lines,heavy-load railways and partial highspeed railways,and it is expected to be applied to higher speed railway systems on a large scale after optimized and deepened research in the future.Yet with the increase of train running speed,the wheel-rail dynamic load increases sharply,and the ballast layer vibration becomes increasingly intense.The violent vibration of ballast layer will aggravate the ballast particle wear and breakage,migration and rearrangement,which has a non-negligible impact on the service performance of the ballasted track bed.This paper makes a research on the vibration characteristics and transmission mechanism of the ballasted track bed under the train load.The specific research contents and results are as follows:(1)Establish a discrete element model of the ballasted track bed,a multi-body dynamic model of the upper track frame structure of the ballasted track.The two above are combined to form a complete ballasted track structure,of which the partial sleepers are set as the information interchange medium to conduct two-way data transmission to carry out DEMMBD co-simulation to repeat the actual service state of the ballasted track bed.(2)Classify the parameters required for the high-speed railway ballasted track cosimulation model,obtain relevant intrinsic parameters by employing indoor experiment measurement,existing research investigation,and factory consultation,and obtain relevant contact parameters by the combination of experiment and simulation calibration.All the required parameters are confirmed by the secondary calibration eventually,and the reliability of the model is verified in combination with the simulation of specific working conditions.(3)Simulate the specific working conditions by fixed-point excitation to analyze the state change of ballasted track bed before and after cyclic loading,the vibration form,state,intensity and the internal and external factors,the ballast layer kinetic energy distribution characteristics and vibration attenuation mechanism,as well as the effects of different frequency loads on ballast vibration,and analyze the relationship between load frequency and ballasted track bed deterioration further.(4)Simulate the specific working conditions by moving load to analyze the size and distribution of the vibration intensity of the moving wheel load and the track irregularity,the effect of the track irregularity on the single ballast particle and the overall ballasted track bed,as well as the particle flow migration,the distribution characteristics of the contact force and the evolution rule,and reveal the relationship between the ballasted bed degradation and the two above.