Breakage of ballast particles can significantly affect the load response behavior and field performance of ballast layers in railway track structures. However, the particle contact and the associated micromechanical behavior of the ballast layer have not been thoroughly investigated. This research introduced the springlike bond in previous clump-based model to form the breakable cluster-based model by comparing the obtained results to experimental findings. A direct shear test model for railway ballast based on the discrete-element method (DEM) is developed with new parameters set selected and validated by closely matching the predicted shear stress–strain behavior with laboratory test results. Then, the DEM model was used to simulate the predicted results to study the fracture and movement of individual ballast particles. Microscopic response under different loadings has been investigated including particle displacement, velocity, and contact force vector.
Yan et al. (2026) studied this question.