急陡黄土坡面细沟侵蚀的水动力学特性试验研究

通过组合不同坡度(25°,30°,35°,40°,45°,50°)、不同流量(0.6,1.0,1.5,2.0,2.5 L/min)的室内放水冲刷试验,对急陡黄土坡面细沟侵蚀发生过程中的细沟水动力学特性进行了研究。结果表明:细沟水流平均流速随细沟的发育呈现出先减小后稳定的变化趋势。细沟流的雷诺数Re在199.996～873.482变化,且主要受流量的影响,随着流量的增大呈线性关系;而弗劳德数Fr在整个细沟发育过程中均大于1,表明细沟流均处于急流范围,且与流量呈倒数关系,随着放水流量的增大Fr呈曲线减小。阻力系数f随着流量的增加而增大,且与雷诺数之间存在f=a·Re~-~b(a、b为系数)的幂函数关系。

Hydraulic Characteristics of Rill Erosion on Steep Loess Slope

The hydraulic characteristics of rill erosion were studied by using runoff scouring experiment under the different steep Loess slope gradients(25°,30°,35°,40°,45°,50°) and the different flow discharges(0.6,1.0,1.5,2.0,2.5 L/min). The results showed that velocity decreased first,then kept smooth and steady as the scouring time. The Reynolds number of the flow varied between 199.996 and 873.482 in the erosion process. It was affected mainly by the flow discharge which was in a linear relationship with flow discharge. The Froude number of flow was larger than 1 in the whole experiments,which indicated that the rill flow belonged to the supercritical flow condition. Meanwhile,the Froude number of rill flow was in a reciprocal decreased relationship with flow. Darcy-weisbach resistance coefficient (f) was positively related to flow and was in a power function relationship with the Reynolds number.