基于休止角模型的非均匀沙分级起动流速公式

利用临界状态下的泥沙颗粒受力与休止角的关系建立了非均匀沙的临界平衡方程式，并且以此为基础在假设底部瞬时流速符合正态分布以及对数正态分布的条件下求出了两个起动概率模型。在这两个起动概率模型基础之上推导出了两个非均匀沙的起动流速模型，并且利用现有的实验数据以及野外数据对模型进行了检验。分析表明基于对数正态分布底部流速得到的非均匀沙分级起动流速模型具有比较高的精度。

Study on the Incipient Velocity for Non-uniform Sediment Based on the Concept of the Angle of Repose

Based on the relationship of relavent forces acted on particles and the angle of repose at the condition of incipient motion, the author get two pickup probability models for sediment entrainment under the normally distributed instaneous velocity and log-normally distributed instantaneous velocity and hence two incipient velocity for nonuniform sediment models are derived. The results are compared with the published experimental data and field data and the results show that the mechanism of incipient motion of gravel and cobble which are the main components of mountain river bed may be different from that of sand. The analysis implies that the results for the log-normal distribution reveal a significant improvement of accuracy for the mixtures with or without gravel and cobble.