风沙环境下沙漠路基风蚀破坏数值模拟研究

基于Fluent气固两相流,运用k?ε湍流模型,对风沙环境下沙漠路基的风蚀破坏规律进行数值模拟研究。分析路基不同横断面下风沙流扰动、增速、减速、恢复的过程,以及路基障碍物的存在对风沙流扰动后造成的风速减弱区和恢复区,总结路基坡面特征点的风速变化规律,与现场实测结果作比较,二者具有很好的一致性。研究结果表明,不同路基横断面下风速减弱区和恢复区的分布对路基高度变化敏感,受边坡坡率的影响较小,不同路基高度、不同边坡坡率下路基沿程风速变化明显不同。边坡坡率一定,随路基高度的增加,路基周围流场扰动被增强,迎风坡坡顶风速增大显著,背风坡坡底风速下降愈明显;路基高度一定时,边坡坡率越小,路基沿程风速变化越平缓。当边坡坡率为1:3时,路基模型高度由1m增加到3m时,迎风坡坡顶风速增加12%,背风坡坡底风速降低约80%。建议为避免沙漠路基的风蚀破坏,路基高度不宜太大,边坡坡率较小为宜。

Numerical simulation studies on wind erosion damage for desert subgrade in sandstorm environment

Applying gas-solid two-phase flow of the Fluent, using turbulence model, we could research the wind erosion and failure pattern of the desert roadbed. After analyzing the sand process that includes disturbance slowing, growth recovery for the different cross-sections of the sand subgrade, the weakened and restore area that result from the existence of the sand roadbed as obstacles, we can summarize the regular pattern of the wind change for the feature point section of the roadbed. Through comparing the data, both on-site test data and simulated data have good uniformity. Research results show that under different roadbed cross-sections the distribution of the weakened and restored area is highly sensitive to the changes of different roadbed height and smaller influence on the slope gradient. The different slope gradient along the road winds is obviously different from all kind of height and roadbed cross-sections. When the slope gradient is fixed，with the increase of roadbed height the flow disturbances is enhanced significantly around the roadbed and the wind speed of windward slopes increases obviously on the top and the wind speed of wind slope dropped significantly near the bottom. The height of the subgrade is certain: the smaller the slope is, the gentler the wind along the road changes. The slope gradient of 1/3 shows: when the embankment height increased to 3m by 1m, the wind speed on the top increase 12% and the wind speed of wind slope reduces 20% near the bottom. In order to avoid the wind erosion damage of desert roadbed, we suggest that the height of the roadbed should not be too tall and the smaller slope gradient is advisable.