砂卵石河流粗化完成后细沙补给对河床阻力的影响

Influence on flow resistance in armoring channel by fine gravel supply

结合Venditti关于细沙补给对河床活动性影响的分析,引用修正后的Einstein-Barbarossa方法对河床阻力进行划分,探讨了细沙补给对砂卵石河流冲刷粗化完成后河床阻力变化的影响。研究结果表明:在一定量细沙补给的条件下,沙粒阻力与床面阻力的比值先减小后增大,形状阻力与床面阻力的比值先增大后减小;水流克服表面阻力损失的能量随沙粒阻力减小而减少,进一步导致水流损失的机械能减小,河床上大颗粒泥沙获得的能量增大进而导致其活动性增强;河床上活动的泥沙颗粒与裸露大颗粒泥沙之间不断接触碰撞形成局部能量交换,裸露大颗粒泥沙通过水流方向的动量交换所产生的颗粒剪应力增大,这可能也是河床上大颗粒泥沙活动性增强的一个原因。

Based on the analysis by Venditti, the effect on bed resistance by fine gravel supplying after channel armoring is discussed by modified Einstein - Barbarossa method. The result showed that： when sand （D50= 3.0mm） supplied to the flume after river armoring, the ratio of grain resistance and bed resistance decreases and then increases while ratio of shape resistance and bed resistance is opposite. Friction of skin surface resulting in loss of energy is reduced with decreasing of sand bed resistance. Energy on the big particles increasing which led to an increase in its activities enhanced. Constant contact with the collision between the sediment and the formation of large particles on the bed activities of local energy exchange, large surface particles with shear stress by exchanging the flow direction of the momentum, which may also be a cause to enhance activity of large particles on the river bed.