Numerical investigation on compaction operations of railway gravel ballast based on DEM-MBD coupling method

Compaction is an essential process in the maintenance of ballasted railways. However, unreasonable operating parameters can reduce compaction efficiency and increase maintenance costs. Previous studies have hardly addressed the impact of compaction on improving the mechanical properties of the ballast bed. In the study, the dynamic equations of compaction are established, and a novel model of compaction based on DEM-MBD coupling method is developed. Furthermore, the parameters of the compaction are optimized from a macro and micro perspective. The research results show that the compaction mainly increases the coordination number of the ballast in the upper area of the ballast shoulder, and the maximum growth rate is 17.45 %. The study reveals that there is no positive correlation between the compacting effect and the excitation frequency. The optimal frequency range for compaction is 25–32 Hz. This study can provide key theoretical support for the parameter selection of on-site compaction for line maintenance.