Micro-analysis of lateral ballast resistance of seismic characteristics

The ballast bed becomes loose in the event of earthquake, as to track lateral resistance ability, even if no visible defects are found in on-site inspections. The behavior of ballast materials subjected to earthquake vibrations is dependent on a variety of factors, including amplitude, frequency, as well as the particle properties, for example, ballast degradation. Motivation for the investigation reported here is based on lateral ballast resistance after vibration. In this research, the discrete element method (DEM) was applied to simulate the seismic characteristics of ballast bed, where the irregular ballast particle was constructed; the interlock of ballast can be well modeled. The nonlinear contact force model with Mohr-Coulomb is adopted to model the clumped particles. A full-size track on a shaking table DEM model was developed, the sleeper lateral ballast resistance force index, and slope ballast particle displacements were analyzed under different vibration accelerations, vibration duration and vibration frequencies, compared with existed same size tests. The purpose of such modeling is micro-analysis of ballasted tracks under seismic effects. DEM test results clarified that sleeper lateral resistance was governed by seismic response. The lateral ballast resistance decrease with vibration accelerations, vibration duration and vibration frequencies, agreed with the tests results.