Comparison On Vertical Dynamic Interactions Between High-Speed EMU And Different Track Structures

In the recent years, with the rapid development of China high-speed railway, more than 19,000km of high-speed railways have been built and a large high-speed railway network that almost covers the whole country has been formed. Since there are many types of high-speed railway track structures, and different lines usually adopted different types of track structures, high-speed Electric Multiple Units(EMU) are always running on different types of tracks. There are many previous researches on dynamic interaction between high-speed EMU and some kinds of track structures, but only few worked on comparison of the dynamic interactions between high-speed EMU and the different types of track structures. Since structures and parameters of different types of tracks are obviously different, it is necessary to compare the running smoothness, safety and rail/wheel dynamic interactions of high-speed EMU running on different track structures. It will provide reference for evaluating the adaptability of high-speed EMU to different track structures.Based on vehicle-track coupled dynamics, vertical coupled dynamic models of high-speed EMU and different tracks are established respectively. The ballasted track model considers three layers of stiffness and damping which are respectively provided by fasteners, track bed and subgrade. Slab track model considers two layers of stiffness and damping provided by fasteners and CA mortar layer. Double-block track only considers one layer of stiffness and damping provided by fasteners.Random track irregularities sample is obtained through numerical simulation according to the Power Spectrum Density of China High-speed railway ballastless track. Simulations of dynamic interactions between high-speed EMU and different track structures are carried out. Dynamic indices of high-speed EMU running on different types of tracks were compared from perspectives of running smoothness, safety and wheel/rail dynamic interaction.Since random track irregularities can be regarded as a combination of harmonic waves of different wavelength and amplitude, and different wavelengths have different effect on the interaction between the vehicle and the track, it is necessary to compare the dynamic interaction between high-speed EMU and different track structures under the excitation of harmonic wave type irregularities. This thesis firstly analysed the change law of running smoothness, safety and wheel/rail dynamic interaction indices, as wavelength and amplitude of track irregularity increase respectively. Then, the dynamic indices of the high-speed EMU running on different track structures under the excitation of harmonic wave type track irregularity were compared.Since short wave track irregularity may cause an impact on both the vehicle and the track, thus choose rail weld joint irregularity as excitation to compare the dynamic interactions between high-speed EMU and different track structures. The changes of the running smoothness, safety and wheel/rail dynamic interaction indices as wavelength and amplitude of short wave increase are analyzed. Then the dynamic indices that high-speed EMU running on different track structures under rail weld joint irregularity are compared.Through the comparison, it is found that there are some differences on the vertical dynamic interactions between high-speed EMU and different types of tracks under the excitation of track random irregularities, harmonic wave type track irregularity and rail weld joint irregularity. The differences between the slab track and the double-block track are relatively small; the differences between ballasted track and ballastless track, specificly for the slab track and the double-block track, are relatively obvious.