基于等效粒径概念的非均匀沙起动条件

Study on incipient condition for non-uniform sediment based on concept of equivalent grain size

基于Parker提出的非均匀沙起动两种极限状况,提出了一个简单的等效粒径表达式。通过取不同的荫蔽参数,该等效粒径表达式可近似表达8家有代表性的非均匀沙起动公式的荫蔽暴露作用,这表明由于床沙特性和粗化程度的不同,荫蔽参数本应是不同的。用韩其为整理的长江寸滩站卵石起动资料,回归得到寸滩站卵石起动计算公式。运用于王兴奎整理的范围更宽的寸滩站资料时,结果符合较好。为长江寸滩站合理选用卵石起动条件提供了依据。

It is convenient to use the concept of equivalent grain size to study the incipient motion condition of non-uniform sediment.A simple formula for computing equivalent grain size is put forward based on the concept of two limiting cases,which was introduced by Parker.This formula considered the variation of hiding parameter can approximately simulate the hiding effect of eight typical incipient condition formulas.It indicates that the hiding parameter should be variational along with the change of bed materials and bed armoring degree.Analyzing the experimental data of Cuntan Station in Yangtze River obtained by Han Qiwei,a simple incipient velocity formula is eslablished,the results of this formula are in good agreement with the experimental data given by Wang Xingkui.It is useful to select appropriate incipient equation for non-uniform sediment in Cuntan Station.