Insights into particle breakage induced macroscopic and microscopic behavior of railway ballast via DEM

Particle breakage greatly affects the stability of ballast beds and safe operation of train traffic. Existing particle breakage simulation methods suffer from shortcomings including non-breakable sub-particles and the low computational efficiency. To tackle this challenge, this paper first simulated the particle breakage by using the particle cutting method and then studied the evolution law of particle breakage of ballast specimens subjected to monotonic triaxial compression loading. The breakage-related macroscopic and microscopic behaviors including the stress–strain relation, particle rotation, and fabric anisotropy were simulated and analyzed accordingly. The results show that the rate of ballast particle breakage is the fastest at the initial loading stage, and then decreases with increasing axial strain. The ballast particle breakage mainly occurs within the shearing bands, and the severity of particle breakage increases with increasing confining pressure. The ballast particle breakage reduces the dilation, peak strength, and the degree of anisotropy of the normal contact forces, the long axes of ballast particles, and the contact normals. Such trends become more significant as confining pressure increases. An improved inter-particle contact system lags behind the particle breakage. The greater the confining pressure, the faster the inter-particle contact system stabilizes after the particle breakage.