【摘要】 分析了现有起动标准的不足之处。在制定起动标准时,不但要考虑水流条件,还必须考虑泥沙颗粒在床面的相对位置。对同一粒径的泥沙颗粒,其起动条件不是一个常量,而是位于一个区间,它随颗粒在床面的相对暴露度而变化。根据力学原理,推导了泥沙颗粒起动时的临界无量纲切应力公式,并对其系数取值进行了理论计算。计算结果表明,对同一粒径、在同一起动状态下,泥沙颗粒的起动临界条件并非一个常量。并从理论上分析得到了临界值的范围,对个别及少量起动,其无量纲临界切应力为0 021～0 042及0 041～0 062。更多还原

【Abstract】 The shortage of the current standards for estimating the incipient motion of sediment particles is analyzed in this paper The standards for estimating incipient motion of sediment not only should consider the condition of river flow, but also consider the relative location of sediment grains within riverbed The condition of incipient motion for one diameter grain is not a constant, but a variant located in a region and varying with the relative expose degree of the grain The formula for calculating the conditions of threshold motion is obtained according rolling mode based on force and momentum balances, and the value of dimensionless critical shear stress of each status is calculated theoretically更多还原