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首页> 外文期刊>Earth Surface Processes and Landforms: The journal of the British Geomorphological Research Group >The effects of kinetic sorting on sediment mobility on steep slopes
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The effects of kinetic sorting on sediment mobility on steep slopes

机译：动力学分类对陡坡沉积物迁移率的影响

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In poorly mobile static armour, sorting is usually considered the result of hiding/exposure effects.We called this effect 'static sorting' in opposition to very efficient grain-to-grain mechanisms produced by a mobile mixture, called 'kinetic sorting'. We hypothesized that kinetic sorting can be an important contributor to the morphodynamics of mountain streams and attempted to demonstrate this with new flume experiments. Two long runs were produced with natural poorly sorted sediments, and with transport stages of the coarse fraction (defined by the ratio between the shear stress and the critical shear stress for transport), smaller and higher than 1, respectively. Both runs produced an efficient transfer downstream of the injected material, but with a major difference: the first run (no kinetic sorting) produced permanent armour figuring clusters, akin to what has already been observed in similar experiments; the second run (with kinetic sorting) also produced bed armouring, but this armour was periodically totally destroyed, leading to substantial bed erosion. This phenomenon was explained by kinetic sorting, the effects of which are to produce an efficient downward migration of fine materials and bed surface armouring. The consequence is that fine materials are hidden to the flow during aggradation, allowing the slope to attain values much steeper than would have been expected at equilibrium for the mixture. However, whereas the surface armouring tends to stabilize the bed, construction of a layer of fine sediments at the subsurface also contributes to making it very unstable. These two contradictory effects explain the complex bed behaviours and the existence of very large bedload and slope fluctuations.
机译：在活动性差的静态装甲中，通常将分类视为隐藏/暴露效应的结果。我们将此效果称为``静态分类''，与由移动混合物产生的非常高效的粒间机制相反，称为``动力学分类''。我们假设动力学分类可能是山间溪流形态动力学的重要贡献者，并尝试通过新的水槽实验证明这一点。产生了两个长期运行，其中天然沉积物分类不佳，并且运输阶段的粗级分（由运输过程中的剪切应力和临界剪切应力之比定义）分别小于和大于1。两次运行都有效地转移了注入材料的下游，但有一个主要区别：第一次运行（没有动力学分选）产生了永久的装甲图集，类似于在类似实验中已经观察到的;第二次运行（采用动力学分选）也产生了床装甲，但该装甲被定期完全破坏，导致床层大量腐蚀。动力学分选解释了这种现象，其作用是使细料有效地向下迁移，并使床面铠装。结果是细小物料在凝结过程中隐藏在流动中，从而使斜率获得的值比混合物在平衡时所期望的值陡得多。然而，尽管表面加固趋于使床稳定，但在地下构造一层细小的沉积物也使其变得非常不稳定。这两个矛盾的作用解释了复杂的床层行为以及非常大的床层荷载和坡度波动的存在。

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