A study on the depositional law of road cutting in the tengger desert

Abstract

In this study, the characteristics of wind-blown sand in the hinterland of the Tengger Desert and the regularity of sand deposition in road cutting are studied by combining a field test and numerical simulation. Firstly, the meteorological observation system is used to obtain the long-term monitoring of the Tengger Desert hinterland, and the perennial wind speed, wind direction, and strong wind period are obtained. Then, a three-dimensional ultrasonic anemometer and stepwise sand accumulation instrument are used to measure the transient wind-blown sand velocity and density at the top of the cutting slope, which provide the basis and verification for the numerical simulation. Finally, Fluent software (2020R2) is used to establish two numerical models with and without grading. Based on Euler's two-fluid theory and fluctuating-wind user-defined functions, the movement of wind-blown sand in the cutting section of the desert hinterland is simulated, and the regularity of sand accumulation in the cutting section is obtained. The main conclusions are as follows: (1) The strong wind period in the hinterland of the Tengger Desert in 2021 mainly occurs from April to August, and the mainstream wind direction is concentrated in the WSW and SW directions. (2) The sand in the hinterland of the Tengger Desert is mainly medium-fine, and the particle size range is mainly concentrated at 0.075-0.250 mm, accounting for 98.2% of the total sand; the curve of the wind-blown sand density with height is oblique and L-shaped. (3) The method of grading excavation is beneficial to reduce the sand accumulation rate on the road's surface.