Novel discrete element method–multi‐flexible body dynamics coupled mechanical analysis for self‐compacting concrete pouring in CRTS III slab track construction

Abstract The self‐compacting concrete (SCC) filling layer is a key component of slab tracks, serving to connect the upper and lower structural layers. Its pouring quality is sensitive to construction temperatures and directly influences the serviceability of high‐speed railway track structures. To improve the quality and efficiency of SCC pouring, an improved fresh SCC flow model was established through fluidity and rheological tests. Furthermore, a multiscale coupled analysis model for the pouring process, integrating the Discrete Element Method and Multi‐flexible Body Dynamics, was developed and validated via full‐scale tests. The flow state of SCC within an enclosed space was accurately characterized. The mechanical interactions between the SCC and the track structure were revealed, and the effects of typical pouring parameters on key construction indicators were analyzed. The results indicate that the rebar network significantly alters the SCC flow pattern and the pouring time. The track slab exhibits nonuniform upward floating, with a maximum vertical displacement of approximately 0.97 mm occurring near the pouring hole, making this region critical for construction control. The hydration time and construction temperature significantly affect the buoyancy, displacement, and pouring time. To ensure construction quality, the hydration time should be restricted to 60 min when the construction temperature exceeds 15°C and to 90 min when it falls below 15°C. This study offers effective guidance for improving the construction quality of slab tracks.