土壤风蚀物中沙粒的动力学特性分析

Analysis of dynamic characteristics of sand grains in wind erosion soil

该文以内蒙古阴山北部的典型农牧交错带耕地为试验区,采用SC-I型沙尘采集器收集跃移沙粒,对收集到的土壤风蚀物进行分析整理,得出了沙粒动力学计算的各重要参数,并从单颗粒土壤在气流中所受的作用力出发,紧密联系野外实验测得的数据,采用4/5阶RKF算法,对沙粒不同受力状况下的运动轨迹和运动特征进行分析。研究表明沙粒粒径愈小发生漂浮所需要的条件愈低,随粒径的增大要求达到的旋转角速度ω、垂直起跳初速度v0越来越大,而小于0.075mm的颗粒容易在脱离地面后,浮在空中从而成为悬移的主体;同时得到了沙粒最大跃移高度Hm关于风蚀物粒径D和垂直起跳初速度v0的通用双因子预测模型。研究为今后风沙运动力学理论的深入研究及土地荒漠化的防治提供依据。关键词:风蚀,动力学特性,土壤。

The wind erosion sand grains of the cultivated land in the typical agro-pastoral transitional zone in the northem foot of Yinshan Mountain in Inner Mongolia were collected with SC-I sand harvester. The collected sand grains were analyzed to calculate the essential parameters for dynamics of sand grains. In the view of acting forces of single soil grain in airflow and the data measured in fields, four-fifth Runge-Kutta-Felhber （RKF） algorithm was adopted to study the trajectories and movement characteristics of sand grains with different force conditions. The results showed that the floating state happened easier with the decreasing of the sand grain diameter. The rotational angular velocity （w） and vertical initial lift-off velocity of sand grain （v0） were required to be higher when the sand grain diameter increased. Therefore, the sand grains with the diameter less than 0.075 mm were the main grains suspended in the air, and the general double-factor prediction model of maximum height （Hm） of sand grain was constructed in terms of the diameter （D） and vertical initial lift-off velocity （v0） of wind erosion sand grain. By studying the wind erosion characteristics in the region, some foundations are provided for the fiurther research on the wind erosion dynamics characters and soil desertification prevention measures.