Experimental study of the sand deposition patterns on railway tracks under different subgrade structures in desert areas

Wind-blown sand hazards are a major threat to the safe operation of railways in arid regions. To systematically investigate how different subgrade structures affect sand transport and deposition around railway tracks and slopes, wind tunnel experiments and lagrange three-dimensional numerical simulations were conducted to simulate the airflow patterns and sand transport processes under three typical structural conditions: full subgrades, full bridges, and subgrade-bridge transition sections. The results indicate that the airflow velocity within the model height exhibits a typical "W" distribution along the flow direction, with significant differences in flow disturbance intensity and sand accumulation patterns. The full subgrade structure induces the strongest airflow interference, resulting in the highest sand deposition on the windward slope, followed by the leeward slope, with the most severe accumulation occurring in the track area. When a train model is introduced, sand accumulation on the leeward slope increases, with the accumulation on the windward side reaching 87% of that on the leeward slope, and sand deposition on the track increases by approximately 57%. In contrast, the bridge structure demonstrates superior ventilation, resulting in the least sand accumulation on the track, although this increases by about 56% with the addition of a train. The transition section exhibits intense wind-sand interaction, with the amount of sand accumulation on the track falling between those for the subgrade and bridge structures, and consistently higher deposition on the windward side than the leeward side. After introducing a train, the sand accumulation on the track in the transition section becomes comparable to that for the bridge structure.