Discrete element analysis of the dynamic behavior of ballast track-subgrade system under train dynamic load

To study the dynamic response law of the ballast track-subgrade coupling system under the action of train dynamic load, considering the real shape of ballast particles, a refined discrete element model of the rail-sleeper-ballast bed-subgrade coupling system was established. The established model can realistically simulate the coupling mechanism between irregular ballast particles, between track panel and ballast bed, and between ballast bed and subgrade under train dynamic load. The validity of the established model is verified using on-site measurement results. This study, from a microscopic perspective, focuses on particle contact forces, vibrations, and frictional energy consumption in the rail-sleeper-ballast bed-subgrade coupling system under train dynamic load and investigates the influence of train speed and axle weight. Results show that an increase in train speed and axle weight enhances the number and probability distribution of strong force chains between ballast particles, increasing the risk of particle breakage and deterioration. The influence range and depth in the ballast bed-subgrade system increase with the train's speed and axle weight. Due to the granular nature of the ballast bed, the vibration acceleration distribution of ballast particles under train dynamic loads is relatively random. Overall, the vibration level of the ballast bed increases with train speed and axle weight. The frictional energy consumption of ballast particles rapidly grows as the train's bogie load passes, and the effect of train axle weight on the frictional energy consumption of ballast particles is more significant than the train's speed.