| 何文社,杨具瑞,方 铎,曹叔尤.泥沙颗粒暴露度与等效粒径研究[J].水利学报,2002,33(11):0044-0048 |
| 泥沙颗粒暴露度与等效粒径研究 |
| Relative exposure degree and equivalent grain size of non uni form sediment |
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| DOI： |
| 中文关键词: 泥沙起动 相对暴露度 等效粒径 非均匀沙 |
| 英文关键词: incipient of sediment relative exposure degree equival ent grain size un-uniform sediment |
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| 摘要点击次数: 1786 |
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| 中文摘要: |
| 回顾了对暴露度的研究现状及存在的问题。提出了一种定义暴露度的方法及其计算式，同时得到了计算暴露度Δ及暴露度系数ξ的表达式。经过分析，给出了ξ的取值范围为0～1，它随颗粒在床面的位置而变。同时提出了等效粒径的概念及其计算方法。并对不同粒径，在床面不同位置的暴露度、暴露度系数及等效粒径进行了计算。对非均匀沙，当相对暴露度系数一定时，大于平均粒径的泥沙颗粒的等效粒径较同等粒径均匀沙的等效粒径小，容易起动；小于平均粒径的颗粒较同等粒径均匀沙的等效粒径大，较难起动，等于平均粒径的颗粒与均匀沙等效粒径相当。经分析等效粒径是一种较符合实际的方法，且公式简单、使用方便。 |
| 英文摘要: |
| The expressions for calculation of exposure degree Δ and exposure coefficient ξ are proposed.It is found that ξ is ranging from O to 1 and dependent upon its position relative to the river bottom.Furthermore,the concept of equivalent grain size and the method for calculation is suggested.Calculations of exposure degree,exposure coefficient and equivalent grain size for grains with various size located at different position relative to the riverbed are carried out.It is concluded that the equivalent size of particles larger than average diameter in non uniform sediment movement is smaller than that for uniform sediment movement if the exposure coefficient is constant.It means that in this case the particles larger than average diameter are easy to incipient. |
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