中文摘要：

通过理论分析提出了与泥沙起动水力条件及泥沙重度有关的泥沙等效粒径的概念及其计算方法，并在此基础上提出了一种计算粗化后床面沙粒粗糙尺度的简化公式，对其取值方法及区间进行了说明。该式表明床面上沙粒粗糙尺度不仅与泥沙颗粒的重度及水的重度有关，且与一定水流条件下形成粗化层时床面上泥沙颗粒的最大起动粒径有关。采用国内外70组天然河道及试验室实测资料，对本文提出的床面沙粒阻力计算公式进行了验证，结果表明该公式的计算精度令人满意。该公式可以用来计算冲积河流粗化后的床面沙粒阻力。

英文摘要：

Based on a theoretical analysis, a concept and a the equivalent grain size of sediment in this paper. Then, the magnitude of sand-grain roughness on an armored bed the range for sand-grain roughness were further discussed. method have been advanced at first to calculate a simplified formula was developed to compute surface of alluvial river, and the approach and The formula indicates that on an armored bed surface of alluvial river with a given hydraulic condition, the sand-grain roughness is closely related not only to the specific weights of sand-grain and water, but also to the maximum grain size of incipient motion of sediment. Finally, 70 data sets measured in natural river channel or experiments were used to perform the identification on the simplified formula. A good agreement between the calculated results and measured data reveals that the simplified formula is available to calculate the sand-grain resistance of an armored bed surface of alluvial river.