粉砂含量对环形水槽混合床面冲刷特性的影响

Influences of sediment composition on scour of silt-sand mixture bed

粉砂介于黏土与细砂之间,其运动特性独特。开展粉砂运动特性研究,有助于进一步完善泥沙运动基础理论,提升混合泥沙运动数值模拟的精度。基于环形水槽实验,研究了底床粉砂含量对粉砂-砂混合床面冲刷特性的影响。结果表明:当底床粉砂含量在36%~60%之间时,粉砂-砂底床抗冲刷能力增强,且呈现出较好的相似性,当水流流速位于区间0.27~0.41 m/s时相似性更为明显。进一步分析发现,这与底床泥沙的混合效应以及底部切应力的分布有密切关系。上述发现可为粉砂质海岸泥沙运动、海床演变、保护利用等相关研究提供参考。

Silt refers to the transitional sediment fraction between clay and sand with unique dynamic properties.Deepening knowledge on silt dynamics can not only improve existing theories but also increase accuracy of numerical modelling on sediment transport.Based on annular flume experiments,impacts of silt content on scour behaviours of silt-sand mixtures have been studied.The results show that silt-sand mixtures with silt content from 36%~60%have similar stronger resistance to scour,and the similarities and peculiarities of these beds can be most prominent when the current speed ranges from 0.27~0.41 m/s,which were revealed to be closely related to the mixing effects of bed materials and the distribution of bed shear stress by further analysis.The results of this study can provide support for relevant studies on sediment transport,morphological changes,coastal protection and exploitation in silty coasts.