砒砂岩陡坡面径流水动力学特征

Hydraulic Characteristics of Steep Slope Runoff of Pisha Sandstone

为研究砒砂岩地区陡坡面径流的侵蚀规律,为该地区坡面水蚀预报模型的建立提供科学的理论依据,通过室内模拟冲刷试验,对不同冲刷流量和坡度的坡面径流水动力学特征进行研究。结果表明:在试验的冲刷流量和坡度范围内,砒砂岩坡面径流流速随冲刷流量和坡度的增大而增大,它们之间呈幂函数关系。径流雷诺数(Re)随随冲刷流量的增大而增大,40°则是Re变化的临界坡度,此时Re最大,而弗罗德数(Fr)的变化趋势正好相反。当冲刷流量大于4L/min时,径流流态为紊流和急流,其余处理坡面径流流态都为层流和急流。径流Darcy-Weisbach阻力系数(f)随压实度增大而减小,随冲刷流量的增大而增大,60°则是f变化的临界坡度,此时f最大,且f和输沙率有一定的正相关关系。

In order to study erosion rule of slope runoff and provide scientific and theoretical basis for water erosion forecast model in Pisha sandstone region,the hydrodynamic characteristics of steep slope runoff under the different scouring flow discharges and slope gradients were studied in this paper by using indoor runoff scouring experiment.The results showed that flow velocity of steep slope runoff of Pisha sandstone increased with the increase of scouring flow discharges and slope gradients under the flow discharges and slope gradients of this experiment and there were the power function relationships among runoff velocity and scouring flow discharges and slope gradients.The Reynolds number（Re） of slope runoff increased with scouring flow discharges.The critical slope of changes of Re was 40° and Re was maximum at this point.The Froude number（Fr） of slope flow runoff had the opposite trends.The flow regimes were turbulent flow and supercritical flow when flow discharges was greater than 4 L/min and the flow regimes were all laminar flow and supercritical flow at other treatments.The Darcy-Weisbach drag coefficient（f） of slope runoff increased with scouring flow discharges.The critical slope of changes of f was 60° and f was maximum at this point.The drag coefficient had positive correlation with sediment transport rate.