Ji Wang

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.

The interlayer properties of the CRTS III slab track during construction directly affect its long-term service condition. This article introduces time-varying coefficients that characterize the early properties of the interface between track slab and SCC to improve the bilinear CZM. Based on this, an interlayer property evolution model of the CRTS III slab track during construction is established. The evolution mechanism of interlayer properties under complex loads and the influence mechanism of key parameters on them are revealed. The results show that after SCC pouring, the interlayer damage at the corner of the slab becomes a sensitive area due to the combined effects of SCC shrinkage and temperature gradients. Interlayer damage initially manifests at the corner of the slab before progressively spreading toward the center of the slab, influencing the composite performance and force transmission characteristics of the track structure. The interlayer bonding property, shrinkage performance of SCC, and construction temperature substantially affect interlayer damage evolution. To reduce the risk of damage, mineral admixtures and expansion agents can be added as additives to improve the bonding property and minimize shrinkage of SCC. Insulation measures should be taken for SCC during low-temperature construction, and SCC pouring construction below 0 °C and above 30 °C should be avoided.