After the construction of desert highway, the physiognomy changes caused by surface wind erosion and accumulation not only seriously threaten the stability of road structure, but also have a tremendous impact on the safety of the highway operation and the maintenance work on the highway. The purpose of this paper is to explore the change of sand sedimentation and the law of sand transport along the highway in the moving dune areas, and to clarify the change of sand flow and the formation mechanism of sand damage in the moving dune areas. Taking the test section of Wuhai-Maqin Expressway in the hinterland of Tengger Desert as the research object, the on-site observation of sand accumulation and the recording of wind information by small weather stations were adopted, supplemented by CFD numerical simulation method, in order to provide reference for the construction of sand control system in moving dune areas. The study results show that: (1) Dunes not only obstruct wind-drift sand but are also the sediment source condition for forming road sand. The windward dunes near the road are affected by wind and the deposition of sand will quickly bury the road in the strong wind season. (2) Compared with highways with flat terrain, the existence of dunes affects the flow field structure and the distribution of sand sedimentation on the highway, in which, under the influence of the gathering effect, the flow velocity reaches the maximum at the top of the dune and a large low-speed recirculation zone is formed on the lee side of the dune, easily causing sand accumulation. (3) Sediment accumulates at the windward side of the embankment or dune where sandy air current is easy to saturate. However, with the increase of wind speed, in addition to the grit carried by the sandy air current itself, new sand rolled up on the windward side of the dunes also form deposits on the road surface and the amount of sand-accumulation on highway surface and leeward side tends to increase. As a result, for the highway in drifting sand dunes areas, sediment prevention and control measures should be taken actively. It is necessary to remove sediment from the road in time and reduce the moving speed of sand dunes and the deposition range of wind-sand flow, ultimately for the purpose of reducing the damage wind-sand activity causes to the highway in desert.

Using the plane alignment design of the Wuhai–Maqin highway as the background of this study, based on the Fluent–Euler two-fluid model, the response law of the wind–sand flow to the embankment under different angles, different curve radii, and different surface windward factors were studied. Additionally, the accuracy of the numerical simulation was verified by the distribution of sand accumulation on the embankment site. The results show that when the wind–sand flow passes through the embankment, and when the angle between the wind direction and the straight embankment gradually decreases from 90° (vertical) to 0° (parallel), the speed-division range is correspondingly shortened. Under the influence of plane alignment, the diversion effect leads to a certain difference in the flow-field structure at different positions of the line. The convex windward embankment has the effect of dredging the wind–sand flow outward. The concave windward embankment has the effect of gathering the wind–sand flow inward. The dredging and gathering effects of the flat curve on the wind–sand flow decreases with the increase in the radius. In the plane linear design, line direction should be parallel to the dominant wind direction as much as possible. If a flat curve needs to be set, the convex windward curve should be given priority, and a large radius curve should be selected as much as possible.

Aimed at the fragile ecological environment in desert, once the resources along routes are destroyed, it will be difficult to restore the original ecological equilibrium in a short time. This paper studies the ecological-equilibrium-oriented risk evaluation of desert motorway schemes in order to choose route schemes reasonably and prevent the sandstorm aggravation caused by ecological damage. Having insight into the special geographical environment and road construction characteristics of Tengger Desert, the research establishes an index system for the ecological risk evaluation in desert areas from five aspects: the interference of living environment of animals and plants, the destruction of natural ecological landscapes, the pollution of water and soil resources, the development and utilization of natural resources, and the sand fixation of plants and the subsequent maintenance; then it confirms each evaluation index’s weight by using the set-valued statistics method to transform the description of the evaluation indexes to an interval value and furthermore determines the comprehensive ecological risk evaluation level of the route scheme in virtue of the two-dimensional cloud image MATLAB outputs which takes the ecological damage and remediation cost as the basic variables. By constructing the model under the method above, the ecological risk evaluations of two route schemes in Zhongwei sand crossing section of Wuhai-Maqin Expressway have been made. The result shows that the western route scheme’s evaluation grade is “good,” is better than the southern route scheme, is within the scope of acceptable risk, agrees with the practical project condition, and verifies the applicability and effectiveness of the model for ecological risk evaluation in desert areas.