Numerical investigation on multiscale mechanical properties of ballast bed in dynamic stabilization maintenance

Stabilizing operation is indispensable for the maintenance of ballast bed. This study aims to investigate the multiscale mechanical properties of ballast bed during stabilization, thus further improving the maintenance effort. First, the ballast bed experienced tamping operation was established using discrete element method (DEM) and multibody dynamics (MBD) coupling approach. Then, a function to simulate stabilization was proposed based on its working principle, which is more efficient compared to existing studies. Finally, the micro-macro mechanical properties of ballast bed during stabilization were analyzed using the numerical model and stabilizing function we developed. The results indicate that an intense dynamic response occurs on the ballasts underneath the loaded sleeper, and the contacting state and uniformity of ballast bed are significantly improved after stabilization. A prediction formula for the settlement of ballast bed in stabilization is innovatively proposed. In addition, stabilizing parameters greatly influence the macro-mechanical properties of ballast bed. A vertical force of 100-125 kN and a stabilizing frequency of 30-40 Hz are recommended based on the analysis of the settlement, uniformity index, lateral resistance, and support rigidity of ballast bed.