黄土细沟流跌坑的形成与作用机理

中文摘要: 跌坑是细沟侵蚀过程中形成的一种床面形态，其是床面形态和水流流动相互作用的结果。借鉴下切型阶梯-深潭理论采用6种坡度(2°、4°、6°、8°、10°、12°)，5种流量(8、16、24、32、40 L/min)完全组合冲刷试验，系统研究了黄土坡面细沟流跌坑形态发育过程及动力特性。结果表明：跌坑平均深度随坡度的增加而增加，跌坑平均间距与跌坑平均深度的比值随坡度的增加而减小，表明跌坑随坡度的增加发育越加成熟，且流量对两者影响均较少；跌坑发育系数随坡度的增加而增大，其值介于1.01和1.14之间，与细沟阻力系数呈正势变化，表明随着跌坑发育越显著，水流阻力越大，能量耗散越剧烈。相同坡度下，跌坑消能率随流量的增加呈线性减小趋势；而消能率随坡度和跌坑发育系数的增加呈幂函数增加关系，消能率范围在87.28％～98.58％之间，研究结果表明跌坑的发育及作用机制对细沟流流动特性及侵蚀产沙具有重要作用。
Abstract:Drop pit is a kind of bed form developed in rill erosion process,and it is the result from the interaction between rill erosion process and flow characteristics.Six slopes (2°,4°,6°,8°,10°,12°) and five discharges(8,16,24,32,40 L/min) were combined in erosion experiment.Results showed that the average depths of drop pit increased with the increase of slope while average spacing of drop pit decreased.The development coefficient of drop pit increased with the rise of slope,and it was ranged from 1.01 and 1.14 with a positive relationship with SP.With the same slope,the energy dissipation efficiency of drop pit showed a linear decrease trend with the increase of discharge,and it showed a power function increase trend with the rise of slope and SP.The energy dissipation efficiency ranged from 87.28％ and 98.58％.Research results showed that the development and mechanism of drop pit played an important role in flow characteristics and erosion sediment yield.