兰新高铁烟墩风区戈壁近地表风沙流跃移质垂直分布特性

doi:10.7522/j.issn.1000-694X.2017.00078

摘要/Abstract

摘要： 跃移质作为风沙流的主体，其近地表垂直分布规律是风沙物理学的重要研究内容，对防沙工程具有重要的指导意义。受研究条件与观测仪器限制，戈壁特别是极端大风区近地表风沙流结构特性研究较为薄弱。利用多梯度风蚀传感器与阶梯式集沙仪对兰新高铁烟墩风区戈壁近地表风沙流跃移质的垂直分布特性进行了观测研究。结果表明：兰新高铁烟墩风区戈壁沙粒发生跃移运动的2 m高临界风速达12 m·s^-1；戈壁近地表风沙流具有明显的阵性特征，沙粒跃移发生的时间比例在50%以下，与平均风速成正相关关系，与风速脉动强度无显著相关关系；2 m高阵风7级风速下，戈壁跃移沙粒主要集中于地表50 cm范围内，近地表风沙流结构呈"象鼻效应"，跃移质最大质量通量出现在地表2.5~5 cm高度处，沙粒最大跃移高度可达2 m，且沙粒跃移高度随2 m高风速的增加呈指数规律递增。因此，兰新高铁烟墩风区2 m高阻沙栅栏不足以完全阻截戈壁风沙流，是造成烟墩风区兰新高铁轨道积沙的重要原因之一。

关键词: 戈壁, 跃移, 风沙流结构, 风沙流间歇性, 烟墩风区

Abstract: Sand particles in saltation are the main part of wind-blown sand, and features of their vertical distribution is a vital research content in aeolian physics, which is of reference significance for aeolian engineering. Restricted by research condition and observation instruments, the research on features of the saltating sand flux profile over near gobi surface in real time observation is relatively weak, especially in gobi area with strong wind. In this study, wind erosion sensors in five different heights and a gradient sand trap were applied to measure the real-time distribution characteristic of saltating particles in different heights in Yandun Wind District, Xinjiang, China. Results revealed that the threshold velocity for saltation in a height of 2 m in the study area reached 12 m·s^-1 with a threshold friction velocity of 0.65 m·s^-1, and sand transport over gobi was of intermittency, which was below 50% in value during the whole observation period. The intermittency of sand transport was in relation to the average wind speed in the height of 2 m, while it had no significant correlation with the pulsation intensity of wind in a period of 10 min. Also, sand in saltation was mainly transported in a surface layer of 50 cm in a moderate gale, and the curve of the sand flux profile presented an elephant trunk outline, with a maximum mass flux in the heights of 2.5-5 cm. Besides, the saltation height of sand particles increased exponentially with wind speed in the height of 2 m, and in a moderate gale, sand particles could saltate to a height of 2 m. Thus, the sand fence cannot fully intercept wind-blown sand over gobi may be one of the main reasons for the sand deposition on rails of the Lanzhou-Xinjiang high-speed railway in Yandun Wind District.

Key words: gobi, saltation, sand flux profile, intermittency of sand transport, Yandun Wind District

中图分类号:

P931.3

谭立海, 张伟民, 边凯, 安志山, 牛百成, 高扬. 兰新高铁烟墩风区戈壁近地表风沙流跃移质垂直分布特性[J]. 中国沙漠, 2018, 38(5): 919-927.

Tan Lihai, Zhang Weimin, Bian Kai, An Zhishan, Niu Baicheng, Gao Yang. Features of Wind-blown Sand Over Near-surface of Gobi: A Case Study in Yandun Wind District, Xinjiang of China[J]. Journal of Desert Research, 2018, 38(5): 919-927.

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