Wind Regime Characteristics and Flow Field Distribution in Sand-crossing Test Section of Wuhai-Maqin Expressway
In order to study the rule of blown sand activity in the sand-crossing section of Wuhai-Maqin expressway,to clarify the wind environment around the road and the formation mechanism of sand accumulation,so as to provide a scientific sand-prevention basis for road system,a 0.5 km unprotected test road in the same direction is built near the main line of Uma expressway in the hinterland of Tengger Desert.Based on the analysis on the characteristics of wind dynamic environment,the structure of blown sand flow field and the rule of sand accumulation around the roadbed are studied by field experimental measurement and computational fluid dynamics(CFD)numerical simulation.The result shows that(1)The wind direction in the road section is greatly affected by the season.The average annual sand threshold velocity is about 6.26 m/s,and the dominant wind direction is WSW,which is accounting for 11.03%.During the observation period,the number of sand-driving days with wind speed above 5 m/s is 270 d,which is accounting for 73%of the annual number of days,and the number of strong wind days with wind speed greater than 10.8 m/s is 47 d,which is accounting for 13.1%of the annual number of days.(2)The sand transport in the experimental area is mainly from west to east throughout the year with the strongest sand-transport environment in spring and summer.The main direction of blown sand flow is 52°with the direction of road,and the sand hazard along the road mainly occurs in the west.(3)The horizontal velocity of wind flow field around the roadbed changes in the M-shaped,and the maximum wind speed is concentrated at the top of the dune.When the dune is on the windward side of the road,the sand flow is most likely to form sand at the junction of the roadbed and the dune,and the dune will move along the main wind direction and bury the roadbed.When the dune is on the leeward side of the road,the sand accumulates obviously on the leeward side of the roadbed.Strong wind environment and abundant sand sources are the natural conditions for the formation of sand hazard on Wuhai-Maqin expressway.Sand control engineering is supposed to focus on the west side,increasing the surface roughness to control the flow of sand dunes,and then reduce the damage of blown sand activities to highway.
road engineeringsand hazard to highwayfluid simulationblown sand activityflow field distribution
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