基于阻力特性的粗糙度计算方法

床面粗糙度Ks是沙粒阻力计算的重要因素,对流速分布、推移质运动及输沙率等问题的研究具有重要的意义。基于阻力特性,综合考虑水沙条件,建立了以泥沙中值粒径、非均匀系数、水力半径和床面坡度为变量的床面粗糙度计算公式。经实测资料验证,并与其他学者的计算方法进行均方差分析对比发现,基于非均匀沙的Ks计算方法的计算精度明显高于基于均匀沙的Ks计算方法;本文公式既适用于均匀沙粗糙度计算,也适用于非均匀沙粗糙度计算,且计算精度明显高于其他学者的计算精度;床面沙波及泥沙输移对公式计算精度的影响均较小,沙波的影响程度小于泥沙输移的影响程度。

Bed roughness calculation method based on resistance characteristics

Bed roughness (Ks) is a leading factor in calculations of sand grant resistance, and its accuracy is crucial to the determination of velocity distribution, bed-load movement, and sediment transport rate. Based on the resistance characteristics and a comprehensive consideration of water and sediment conditions, this paper develops a calculation formula of bed roughness using the variables of sediment median grain size, sediment non-uniformity coefficient, hydraulic radius, and bed slope, including more hydraulic factors than those in previous studies. This formula is verified against measured data and its mean square errors are compared with those of the previous methods. The verification reveals that it is applicable to the uniform and non-uniform sediment cases, and the bed roughness calculations based on non-uniform sediment achieve much higher accuracy than those on uniform sediment. The effect of sand waves on its accuracy is smaller than that of sediment transport.