人工卵石床面风沙流粒度特征

沉积物粒径分布对风沙沉积物的起动、输送和沉降过程十分重要。不同粒径的风沙沉积物空气动力学特征不同，从而导致其起动机理、输送过程和沉降模式不同。因此，粒度可以作为风沙沉积过程的指示器。戈壁是西北地区的一种重要地貌景观，戈壁风沙流是风沙物理研究的内容之一，但目前研究较少，特别是对戈壁风沙流粒度分布的研究，几乎没有报道。本文利用人工卵石床面模拟戈壁地表，对0.25、0.5、1 m和2 m高度的风沙流粒度特征进行观测，结果表明：沙源、地表状况、风程效应等影响沙粒粒径随高度的变化。沙源近，平均粒径随高度先减小后增加；沙源远，平均粒径随高度增加减小。戈壁表面的不同区域，沙粒粒径级配不同：随高度增加，粗砂，中砂含量降低，细砂、极细砂和粉砂含量增加；随距离增加，中砂含量降低，细砂、极细砂和粉砂含量增加。平均粒径越大，分选越好，偏度越趋于正偏，峰度越趋于变宽。偏度、峰度随分选系数增加而增加。峰度随偏度增加而增加。

The Characteristics of Aeolian Transport Particle Size Distribution over the Pebble Artificial Surfaces

Particle size distribution has an important effect on the aeolian material entrainment, transport and deposition. The mechanism of aeolian sediment entrainment, transport distance and mode of deposition are different for different particle size distribution, therefore, the particle size characteristics of aeolian sediment is a good indicator of aeolian sediment. Gobi is an important landscape in the northwest region of China, and aeolian transport in gobi is one of issue in aeolian research. At present, there is little research on gobi aeolian transport, especially on the sand particle size distribution. In this paper, field experiment data in height of 0.25, 0.5, 1 m and 2 m was used to analyze particle size distribution. The results indicate that aeolian sediment supply, surface situation, wind disturbance control particle size distribution with height. (1) Mean particle size decreases with increasing height in longer distance sediment supply, but in shorter distance, mean particle size decreases with increasing height in certain height and then decreases. (2) Larger particle size impact on gravel surface, wind speed change from sand dunes to gravel surface and wind disturbance causes larger particle reach to higher heights. (3) The larger mean particle size, the better sorting, and skewness become more positive, kurtosis become more leptokurtic. Skewness and kurtosis increase with increasing sorting. Kurtosis increases with increasing skewness.