Dynamic Behavior Analysis of High-Speed Railway Ballast under Moving Vehicle Loads Using Discrete Element Method

Considering the real irregular shapes of ballast particles and complete track skeleton, a two-dimensional discrete element model is built to investigate the dynamic behavior of high-speed railway (HSR) ballasted track. Taking the moving wheel loads obtained from railway vehicle-track coupled dynamics simulation as the excitation inputs, the dynamic behavior of ballast particles in terms of contact force, stress, and vibration response are simulated using the discrete element model. Numerical results show that the ballast particles within the depth of 200 mm under sleepers would be most likely to carry a higher stress level when a vehicle passes by. Vibration amplitudes of ballast particles increase with the increase of vehicle speed, and the acceleration amplitudes rise sharply when the vehicle speed is higher than 200 km/h. Spectrum analyses indicate that the dominant frequencies of particle displacement and velocity are lower than 100 Hz, whereas the acceleration responses contain not only low-frequency but also some medium-frequency components in the range of 150-300 Hz. Simulated results also demonstrate that the vibration amplitudes of ballast particles attenuate with the depth and the longitudinal distance from the sleeper center to the particle. This research work presents mechanical behavior of railway ballast and provides a potential way to reveal the deformation and degradation aspects of railway ballast from the mesoscopic to macroscopic level, while recognizing the limitations of the current discrete element model in quantifying particle breakage.