卵石透水河床渗流阻力研究

大多数卵石河床阻力研究分析了卵石粒径或相对粗糙度对阻力系数的影响，而忽略了对卵石透水层本身的阻力研究。本文用玻璃球在矩形水槽中铺设不同层数的透水层模拟卵石河床，测量了不同渗流量通过玻璃球透水层产生的水头损失及相应透水层的孔隙率；以Ergun方程的无量纲形式，分析了水流通过玻璃球透水层的阻力系数变化规律。实验表明，考虑边壁影响的Ergun方程能很好的描述水槽中不同厚度透水层阻力系数随雷诺数变化的关系。

Experimental Study on the Friction Factor of Permeable Gravel Bed

Flow resistance in gravel-bed rivers is usually investigated by considering variation in relative roughness height, while relevant friction law for the porous permeable layers is not well understood. By applying Ergun equation, this study investigated the friction law of seepage through packed beds composed of glass beads. Different flow regimes were observed with varying head loss measured. The results show that the friction factor decreases with increasing Reynolds number and the data collected for different cases collapse almost into a single curve when the wall effects are considered. Finally an improved Ergun correlation is proposed to evaluate the flow resistance of packed permeable beds with small bed-to-particle ratios.