宽级配卵石河床表层大多为不同粗化程度的粗化层覆盖,现有大多数公式只能反映特定粗化程度下的输沙特性,限制了这些公式的适用性。理论分析和试验结果表明:在同样的来水来沙条件下,粗化程度越高,输沙率越小,在计算中引入粗化程度参数可以较好地提升公式的适用性;粗化层的稳定性对卵石推移质输沙有重要影响,粗化层遭受破坏后,推移质输沙率剧增,现有公式计算结果明显偏小。因此,在计算推移质输沙率时需要科学合理地考虑粗化层破坏导致的输沙率剧增问题。
Abstract
Surface layers of gravel bed of wide gradation are usually covered by armoring layer with different coarsening degrees. Most of the existing bed-load transport formulas could just reflect the characteristics of sediment transport in a certain coarsening degree, hence are of poor applicability. Theoretical analysis and experiment results show that bed-load transport rate decreases as the coarsening degree of armoring layer increases under the same incoming flow and sediment condition. Introducing the parameter of coarsening degree into the calculation could solve this problem. The stability of armoring layer plays an important role in bed-load transport in gravel bed. Bed-load transport rate increases sharply when the armoring layer is broken. The calculation results of the existing formulas are obviously small. Therefore, the sharp increase of sediment transport rate caused by the failure of armoring layer should be considered in calculating the bed-load transport rate.
关键词
卵石河床 /
推移质输沙率 /
粗化程度 /
粗化层稳定性 /
临界条件
Key words
gravel bed /
bed-load transport rate /
coarsening degree /
stability of armoring layer /
critical conditions
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