Mechanical performance of double-block ballastless track structures under different sleeper spacings

Abstract

In high-speed railway ballastless track systems, sleeper spacing governs the density of discrete rail supports and the load transfer path, making it a key parameter affecting rail deformation, internal forces, fastener loads, wheel–rail interaction, and dynamic responses during train passage. This study investigates the influence of sleeper spacing on the static and dynamic behavior of double-block ballastless track. A Hertzian wheel–rail contact model and a finite element model of the rail–fastener–sleeper–track slab system were developed to analyze deformation, stiffness, shear force, and bending moment under static wheel loads. A field-validated vehicle–track coupled dynamic model was further established to evaluate rail vibration, fastener reaction forces, and wheel–rail contact forces during train passage at different speeds. The results indicate that increasing sleeper spacing reduces support density and strengthens the rail span effect. Under static loading, rail deformation and the peak values of rail shear force and bending moment increase, while fastener reactions shift from distributed multi-point bearing to localized concentration near the loading region. Under dynamic loading, the rail vibration response increases with train speed, and larger sleeper spacing further amplifies this effect. As sleeper spacing increased from 500 to 900 mm, the peak rail acceleration increased by 14.81% at 100 km/h and 19.08% at 300 km/h, indicating that larger sleeper spacing further amplifies rail vibration under high-speed conditions. Moreover, larger sleeper spacing intensifies fastener reaction forces and increases the fluctuation amplitudes of vertical and lateral wheel–rail forces, which is unfavorable for vehicle running stability. Overall, excessive sleeper spacing weakens rail support continuity, aggravates local force concentration, and deteriorates the dynamic performance of the track–vehicle system.