Abstract: Aiming at the transporting characteristics of gravel sediment in low water and urgent shoal in mountainous rivers, it is found that incipient motion first starts at the foot of the slopes through the experiment observertions of the gravel on the slopes and theoretical analysis of the phenomenon. According to the gravel sediments stress state at the foot of the slopes, a rolling model is adopted to conduct a theoretic deduction; and the bottom velocity, drag coefficient, gravel underwater grav- ity and the impact of additional gravity are taken into account; then the incipient motion flow formula at the foot of the slopes is deduced, which relates to the slope gradient. Through the flume experiment, the gravel sediment incipient motion flow formula at the foot of the slopes is fitted out, and a comparision with Shamo Fu formula is made.

Key words: gravel sediment , slope , additional gravity , incipient motion flow ;

摘要： 针对山区河流枯水卵石急滩的泥沙输移特点,通过对斜坡上卵砾石的实验现象观察和理论分析,发现卵砾石 边坡坡脚处的泥沙首先起动。根据卵砾石边坡坡脚泥沙的受力状态,采用滚动模式进行理论推导,考虑了底部流 速、阻力系数、卵砾石水下重力及其附加重力的影响,推导出了卵砾石边坡坡脚泥沙的起动流速公式,该公式与边 坡坡度有关。通过水槽试验,拟合出卵砾石边坡坡脚泥沙的起动公式,并与沙莫夫公式进行了比较。

关键词: 卵砾石, 边坡, 附加重力, 起动流速