Dynamic train-track interactions over track stiffness discontinuities in railway track transitions mitigated by resilient materials

Railway track transitions, where abrupt changes between different track sections lead to differential settlement and increased maintenance costs, pose a significant challenge. This often results in considerable track damage and elevated maintenance expenses. In Thailand, the early stages of the high-speed rail project integrate a slab track system from China with conventional ballasted tracks at multiple junctions, underscoring the importance of effectively managing these transition zones. Despite the potential benefits of Under Sleeper Pads (USPs) in ballasted tracks and Under Slab Mats (USMs) in slab tracks for reducing track vibration, impact load, and differential settlement, their usage is not widespread. This paper presents a 3D train-track-soil finite element model that incorporates both USPs and USMs, considering strain-rate effects, to analyze railway track transitions. The model evaluates various pad types across different track locations and train speeds. The results show that USPs can significantly reduce ballast degradation, while USMs help maintain overall track stiffness. The results also show that the combination of USPs and USMs effectively manages track stiffness gradients, achieving a normalized gradient between 0.04 and 0.20, compared to 1.00 in the baseline case. Although the combined use of USPs and USMs offers a promising solution for managing track transitions, careful selection are crucial to avoid potential issues. This research provides a comprehensive framework for understanding and improving the performance of railway track transition zones using resilient materials. It suggests further studies to evaluate the broader applicability of these methods in minimizing track disturbances across various environmental conditions.