均匀球体泥沙典型分布状态及其起动流速研究

Three Typical Distribution States and Incipient Motion Modes of Uniform and Spherical Sediment

为了研究床面泥沙三维随机分布状态及其起动条件,将泥沙颗粒概化为三维球体,采用粒径为12mm的均匀玻璃球,在边长为150mm的立方体容器中进行了床面泥沙随机堆放试验.试验发现,床面泥沙存在3种典型分布状态,统计分析了3种状态各占的比例,建立了对应的泥沙起动力学平衡方程,推导出了3种模式泥沙瞬时起动流速公式.假定3种模式的暴露角均符合正态分布,将3种分布模式对应的起动流速影响函数加权平均,得到基于3种分布状态的泥沙综合起动流速公式.经实测资料验证,本文起动流速公式与不同泥沙粒径起动流速实测数据符合良好.

Random pile tests were carried out using 12 mm glass ball and a 150 mm cubic container,to investigate sediment random distribution states and their incipient motion condition on riverbed surface.Three typical states for sediment distribution have been observed,of which the frequency was statistically analyzed.Sediment dynamic equilibrium equations of the three typical distribution states were set up based on the rolling incipient motion modes,and the formulas of sediment incipient motion velocity containing exposure angle were deduced.According to 2-D exposure angle experiment,it is assumed that sediment exposure angles of three typical distribution states are accord with normal distribution.The total formula of sediment incipient motion velocity was finally acquired considering the influence of the three typical distribution states of sediment on riverbed surface.The results show that the calculated values of the formula in this paper were well consistent with the measured data.