Optimization of transition section treatments between bridge and regular track using DEM coupled simulation

This study investigates the impact of four treatment measures—wedge-shape backfill, asphalt mat, concrete slab approach, and stone column installation—on the dynamic performance of railway transition zones, using a coupled Discrete Element Method and Multibody Dynamics model. A 24 m long full-scale three-dimensional model of the transition section, including the discrete ballast particles and discontinuous subgrade elements, was developed to simulate uneven settlement under cyclic M-wave train loads and evaluate the effectiveness of the treatments. The results reveal that all treatments significantly reduced the uneven settlement of the track, with wedge-shape backfill and stone column treatments showing the most promising results, reducing uneven settlement by 42.2 % and 41.1 %, respectively. These treatments also improved the load-bearing capacity of the ballast layer by increasing particle contacts and reducing particle movement. The stone column method notably suppressed particle movement in the ballast layer by distributing the applied load more effectively. In contrast, the asphalt mat and concrete slab methods showed moderate improvements. This study highlights the importance of enhancing subgrade stiffness in transition zones to mitigate settlement.