Characteristics of wind-sand flow in longitudinal slope embankment section of desert highway

Investigating the wind-sand flow response regularity in the longitudinal slope sections of desert highways provides a scientific basis for selecting the slope of desert roads. This study uses the Tengger Desert section of the Wuhai-Maqin Expressway as a case study, employing CFD numerical simulation methods to calculate and analyze the wind-sand flow field distribution characteristics in different longitudinal slope sections. The results show that: (1) Along with the direction of the incoming flow, the windward and leeward slope toes of the embankment are low-wind-speed zones, with the wind speed at the leeward slope toe being even lower. The higher the embankment, the larger the low-wind-speed zone at the windward and leeward slope toes. As the longitudinal slope increases, the extent of the low-wind-speed zone at the same location along the route also increases. (2) Along the route direction, the wind speed at the windward and leeward slope toes decreases as embankment height increases. At the embankment toe, sand particles are transported from the top to the bottom of the longitudinal slope, and the greater the longitudinal slope, the stronger the transport effect. (3) Along the route direction, the sand accumulation around the embankment gradually gathers toward the bottom of the longitudinal slope as the slope increases. When the longitudinal slope is 3% and 4%, the trend of sand accumulation moving from the windward side at the end of the route to the leeward side at the start of the route is more significant. When the longitudinal slope is less than or equal to 3%, severe sand accumulation within the embankment range is reduced by 86.4% or more compared to when the slope is 4%. (4) Under the same longitudinal slope, the higher the embankment height, the smaller its transport rate. When the embankment height is the same, the greater the longitudinal slope, the greater the embankment transport rate.