Objective  This paper aims to explore the distribution law of the flow field, horizontal wind speed and sand accumulation characteristics in the transition section between the bridge and the roadbed (bridge-road) and near the roadbed, and reveal the formation mechanism of sand damage in the bridge-road transition section.

  Method  By means of numerical simulation, the flow field changes and the characteristics of sand accumulation in the bridge-road transition section and near the roadbed under different incoming wind speeds were studied. And use the numerical simulation of the sand distribution to compare with the actual on-site sand accumulation to verify the accuracy of the numerical simulation results.

  Result  When the wind-sand flow moved to the bridge-road transition section, it was hindered by the bridge-road transition section, resulting in speed divisions. Air flow deceleration zone, current collection acceleration zone, high speed zone, vortex cyclone zone and air flow recovery zone were formed, respectively, and the area of the deceleration zone on the leeward side of the bridge-road transition sectionwas significantly larger than that on the leeward side of the subgrade. Near the surface of the bridge-road transition section, the airflow velocity first decreased (negative value), then increased and then decreased (negative value), and finally returned to the incoming wind speed gradually. At a height of 4.2 m from the ground, the velocity change basically showed a V-shaped distribution, and at a height of 4.4 m from the ground, the velocity change basically showed a double-V-shaped distribution. According to the numerical simulation results, therewas more sand on the windward and leeward sides of the bridge-to-road transition section, and the clearance under the bridge was a good sand-crossing section. Most of the sand particles were transported to the leeward side of the bridge and will not deposit a lot on the bottom of the beam. Sand accumulation on the roadbed mainly occurred on the windward side and rarely on the leeward side.

  Conclusion  As time goes by, the sand near the transition section of the bridge and road will slowly spread to the surrounding area. One part is deposited at the bottom of the beam, causing sand at the bottom of the beam, and the other part jumps over the subgrade and enters the track bed. Therefore, the prevention and control of sand hazards in the transitional section of bridges and roads cannot be ignored. The accumulated sand must be cleaned regularly to prevent sand particles from entering the track bed and steel rails and endangering driving safety.