泥沙起动流速的随机分析

泥沙起动流速是河流泥沙动力学基本概念之一,对泥沙运动及河床冲淤变形研究有着重要意义.天然河流中的泥沙运动多处在紊流状态下,其影响因素极其复杂,具有显著的随机性.本文在总结前人研究成果的基础上,从流体力学层面论述了以作用于泥沙颗粒上的局部流速表示泥沙起动流速的合理性,进一步拓展分析,指出了以往公式的不足,给出了以局部点流速表示的包括散粒体与粘性颗粒在内的全沙起动流速公式,继而与各家公式作了对比；基于随机理论,给出了泥沙普遍动、少量动、个别动的判据,并将均值流速概率化,扩展了泥沙颗粒起动的范围与认知.

Stochastic analysis of threshold velocity of sediment particles

The threshold velocity of sediment particles is one of the basic conceptions of river sediment dynamics.It is significant to the research on the sediment movement and river bed deformation.Sediment in natural rivers is always in the turbulent state,of which the influencing factors are extremely complex and remarkably random.Based on the previous studies,firstly,this paper presents the rationality of the velocity of sediment starting expressed by the local flow velocity of the sediment from the hydromechanics perspective.It indicates the deficiency of the previous formulas and puts forward the threshold velocity formula including granular mixtures and cohesive particles expressed by the local flow velocity.Secondly,according to the randomness theory,the paper presents the criterion condition of different types of sediment incipient motion.It also randomizes the average velocity and expands the range of recognition of sediment incipient motion.Finally,a calculation program of threshold velocity for practical application is developed.The program can be used in various situations,including different particle sizes,different water depths and different ranges of specific gravity of particles.