Track Sand Deposition and Prevention Measures Under Railway Windbreak Walls in Strong Wind–Sand Areas

This study investigates track sand deposition on the leeward side of subgrade windbreak walls along the Xinjiang section of the Lanzhou–Xinjiang High-Speed Railway. Numerical simulations and wind tunnel tests were conducted to compare flow-field reconstruction, sand transport, and track sand deposition under three structural configurations. The results show that a strong shear layer and a large-scale recirculation vortex form behind a single windbreak wall. The local reverse velocity reaches approximately −10 m/s, which can entrain sand particles back toward the track area. Adding a second wall at the leeward slope toe reduces near-surface wind speed to some extent, but local vortices and high-shear zones remain. In contrast, placing checkerboard sand barriers at the leeward slope toe effectively weakens near-surface recirculation and bed shear. This configuration maintains surface shear stress near the track below 0.5 Pa and reduces sand concentration by approximately 60–80% compared with the single-wall structure. At wind speeds of 15–30 m/s, the checkerboard sand barrier maintains strong sand-reduction performance. Near-surface peak sand concentration decreases by about 38–75%, and track sand deposition decreases by about 42–43% relative to the single-wall structure. These findings indicate that checkerboard sand barriers on the leeward side of windbreak walls can substantially reduce the risk of secondary sand deposition induced by the walls. The proposed leeward-side protection measure can effectively mitigate sand accumulation on railway infrastructure, thereby improving the long-term operational safety, resilience, and sustainability of high-speed railways in desert environments under increasing wind–sand hazards.