沙漠公路风蚀破坏规律的数值模拟研究

通过Fluent软件对沙漠公路的风蚀破坏规律进行数值模拟研究。分析公路不同横断面时风沙流扰动、增速、减速、恢复的过程,确定路基(堑)高度、边坡坡率和路面宽度等公路断面设计参数对风沙流扰动的影响,提出沙漠公路路基(堑)风蚀破坏规律。结果表明:路面宽度的改变对路基沿程风速变化影响较小,各特征点处风速变化小于5%。路基(堑)高度和边坡坡率对风沙流扰动的影响较大。随路基(堑)高度增加,风沙流流场的扰动被增强,路基(堑)风蚀破坏越显著,当边坡坡率为1:1时,路基模型高度250 mm时的迎风路肩风速为模型高度60 mm时的1.15倍,其背风坡脚风速降低45%;路堑模型高度250 mm时的背风堑顶风速为模型高度60 mm时的1.05倍,迎风堑脚处风速降低高达80%。建议沙漠公路宜采用中低路基(堑),不宜高填深挖。当路基(堑)高度一定,边坡坡率为1:1.75或1:2时,路基(堑)沿程风速变化平缓,沙漠路肩不易被吹蚀破坏;路堑中堑脚位置处不易出现堆积。其结论与室内风蚀风洞试验结果有很好的一致性。

Numerical simulation of wind erosion damage rules for desert highway

Wind erosion damage rules of desert highway are simulated using the Fluent software. The process of disturbance, acceleration, speed-down, and recovery of the sand flow that is obstructed by different highway cross-sections are analyzed. The influences of main cross-section design parameters such as subgrade (cutting) height, slope, and pavement width on the sand flow are determined; and the wind erosion rules of desert highway subgrade (cutting) are proposed. The results indicate that the influence of the pavement width on wind speed variety is slight, the changes of wind speeds at feature points are less than 5%; but the subgrade (cutting) height and slope have great influence on wind speed variety. The disturbance of sand flow field is reinforced with the subgrade (cutting) height increases, the wind erosion damage of subgrade (cutting) is more evidently. While the side slope is 1:1, the wind speed on the shoulder of windward when the subgrade model height is 250 mm is 1.15 times more than the speed when the subgrade model height is 60 mm, but the wind speed on the bottom of leeward slope decreases 45%; the wind speed on the shoulder of windward when the cutting model height is 250 mm is 1.05 times more than the speed when the cutting model height is 60 mm; but the wind speed on the bottom of leeward slope decreases about 80%. So it is suggested that the desert highway should use middle or low height subgrade (cutting) and shouldn’t be filled highly or digged deeply. While the height of subgrade (cutting) is certain, and the side slope is 1:1.75 or 1:2, the change of wind speed along the subgrade (cutting) is gentle; and the accelerate effect of windward shoulder and the speed-down effect of leeward bottom are inconspicuous. At this time, the subgrade isn’t destroyed by wind erosion and the leeward bottom of cutting isn’t changed by accumulation easily. The conclusions drawn from numerical simulating are consistent with the experiment results perfectly.