基于CFD(Computational Fluid Dynamics)数值模拟,以青海省中灶火省道303公路为研究区域,对流动沙丘区公路路基风沙流场进行了模拟分析,揭示了流动沙丘区路面沙害的形成机制,以期为流动沙丘区路面沙害的防治提供理论依据。数值模拟结果表明:当气流经过流动沙丘和路基时,气流速度产生分区;当存在流动沙丘时,路基周边的减速区范围明显增大,路基坡面和背风坡全部处于气流低速区的范围,沙丘高度以上,在沙丘顶部气流速度急剧增大,受障碍物自身形状的影响,风速变化由“Ω”型分布变为 “M”型分布。当沙丘表面的原有防护体系疏于维护、更新,沙粒在沙丘附近大量堆积,沙丘会慢慢沿主风向移动,成为沙源,掩埋路基而形成沙害。数值模拟结果与现场实际相吻合,证实了数值模拟的准确性。对于流动沙丘区公路的沙害防治,应详细考察当地的地貌形态及风沙流运动规律,定期检查维护原有防护体系,及时清理积沙,既要阻止风沙流对沙丘进行沙源供给,又要防止沙丘本身成为沙源。

This study analyzed the wind-sand flow field of a highway roadbed to reveal the formation mechanism of pavement sand damage, which provides a theoretical basis for the prevention and control of sand damage on a road surface in a shifting dune area. The study area was Highway 303 in Zhongzaohuo, Qinghai Province, China, which was selected based on computation fluid dynamic numerical simulation. The numerical simulation results showed that when the airflow passes through the shifting dune and the roadbed, the airflow velocity is divided into zones. In the presence of a flowing dune, the range of the deceleration zone around the subgrade increased significantly, while the subgrade slope and the leeward slope were all in the low speed airflow zone. On the top of the sand dunes, the air velocity increased sharply and was affected by the shape of the obstacles, which caused the wind speed to change from the “Ω” type to “M” type distribution. When the original sand control system on the dune surface is not maintained and updated, sand grains accumulate in large quantities near the dune. In this manner, the dunes will slowly move in the main wind direction and become the sand source, thus burying the roadbed and causing sand damage. The numerical simulation results are consistent with the actual results obtained, which indicates the accuracy of the numerical simulation. For the prevention and control of road sand damage in the shifting dune area, the local geomorphologic form and the law of wind-sand flow movement should be investigated in detail. Checking and maintaining the original protection system regularly, and cleaning up the accumulated sand in a timely manner will prevent the wind-sand flow from supplying the sand source, and will prevent the sand itself from becoming the sand source.