黄土缓坡细沟侵蚀演化过程及其水流水力学特性实验研究.docVIP

  黄土缓坡细沟侵蚀演化过程及其水流水力 学特性实验研究# 张永东1，吴淑芳2，陈贵怀1，李洪权1，李欢欢1** 5 10 15 （1. 重庆市万盛经济开发区水务局； 2. 西北农林科技大学水利与建筑工程学院） 摘要：本研究采用间歇性室内人工模拟降雨实验，对 15°黄土坡面细沟侵蚀动态发育及其 水流水力学特性时空分布规律进行了研究。结果表明：(1)细沟侵蚀过程为溅蚀-片蚀-跌坑- 断续细沟-连续细沟-细沟崩塌，沟长发育迅速，沟宽和沟深发育相对缓慢。5 场降雨结束， 细沟平面密度、最长沟长、沟宽、沟深较发育初期分别增加了 2.5 倍、10.2 倍、0.8 倍和 1.6 倍；（2）随着降雨历时的增加，坡面流速、水深、雷诺数都呈增加趋势，伴有较小波动； 细沟内流速增长平稳，而细沟内水深与雷诺数呈波动性增长。弗劳德数波动较大，但随降雨 场次的增加而增加。（3）颗粒阻力与降雨阻力随降雨时间增加而减小，形态阻力随降雨场 次增加而增大，叠加阻力前两场降雨波动较大，第三场降雨达到最小，后两场降雨又有所增 加，最终稳定。前两场降雨，颗粒阻力占主导地位，后两场降雨，形态阻力成为主导阻力。 总体上，细沟内阻力最小，上坡阻力最大。 关键词：间歇性降雨；细沟侵蚀；动态演变过程；水力学特性 中图分类号：S157 20 Experimental study on rill erosion evolution and hydraulic characteristics of follow for loess gentle slope Zhang Yongdong1, Wu Shufang2, Cheng Guihuai1, Li Hongquan1, LiHuanhuan1 (1. Water Affairs Bureau of Wansheng Economic Development Zone; 25 30 35 40 2. College of Water Resources and Architectural Engineering,Northwest A F University) Abstract: In this paper, rill dynamic development process and the temporal and spatial distribution hydraulic characteristics of flow were studied on Loess gentle slope of 15 degree through laboratory continuous rainfall simulation. The results showed that: (1) Dynamic development process of rill erosion could be presented as splash erosion-sheet erosion-drop pit-intermittent rill-continuous rill-rill collapse. Rill length developed rapidly and rill width and rill depth developed slower. To the end of the 5th rainfall, rill horizon density, the largest rill length, width and depth respectively increased 2.5, 10.2, 0.8, 1.6 times than initial erosion; (2) Velocity, runoff depth and Reynolds number increased with rainfall accumulation duration accompanied by minor fluctuations. The velocity in rill had a steady growth and runoff depth and Reynolds number in rill increased with fluctuant. Froude number had a larger fluctuation and it increased with the increasing of rainfall sessions. (3) Rain and grain resistance were decreased and form resistance increased with rainfall duration.