Mechanics of Sediment Transport of Graded Materials and Fluvial Sorting

分级材料输沙机理及河流分选

基本信息

批准号：
01550401
负责人：
TSUJIMOTO Tetsuro
金额：
$ 1.41万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1989
资助国家：
日本
起止时间：
1989 至 1990
项目状态：
已结题

项目摘要

Sediment transport of graded materials often shows non-equilibrium behavior and subsequently it accompanies fluvial sorting process. In order to describe the phenomena it brings about, non-equilibrium transport model characterized by pick-up rate and step length for each grain size.When the sediment transport supplied from the upstream region is suppressed, the bed-surface adjusts its composition (size distribution) by selective movement of sediment according to the size. Particularly, the supplied sediment is zero, the bed is coarsened and the transport rate over it becomes zero increasingly from the upstream end (armor coat formation and propagation). While, the suppressed sediment is not zero, all size-fraction of sediment are still transported (the transport rate becomes equal to the supplied one finally) but the bed surface is obviously coarsened (pavement). These two different types of bed coarsening process could be described by the non-equilibrium transport model proposed in th … More is study.Besides monotonous sorting, alternate sortings are often observed : longitudinally alternate sorting and laterally alternate sorting (longitudinal stripes of sorting). These sortings do not require the forced change of supplied sediment. Non-equilibrium transport for each grain size and the change of bed-surface composition brings about an instability of the bed-surface composition. The formation processes could be described by the non-equilibrium transport model proposed in this study.In a stream with longitudinally alternate sorting, the longitudinal change of bed roughness severely changes the turbulent structure and subsequently the characteristics of suspended sediment transport over it. Based on the turbulence measurements, a model to describe the relaxation process of Reynolds-stress distribution due to the change of the bed shear stress was derived, which was a convolution-integral type with an impulse response. The similarity between the turbulent momentum exchange and the turbulent transport of suspended sediment suggested a description of non-equilibrium concentration distribution of suspended sediment with the relaxation model prepared for the Reynolds-stress distribution. Less

分级材料的沉积物运输通常显示出非平衡行为，随后涉及河流分选过程。为了描述其带来的现象，非平衡运输模型的特征是每种晶粒尺寸的拾取率和步长。当抑制从上游区域提供的沉积物传输时，床表面通过根据大小的选择性运动来调整其组成（尺寸分布）。部分地，所提供的沉积物为零，床被粗糙，其运输速率从上游端越来越零（装甲涂层形成和传播）。虽然抑制沉积物不是零，但所有尺寸划分的沉积物仍被运输（运输速度最终等于所提供的沉积物），但是床表面显然被弄脏了（路面）。这两种不同类型的床更粗化过程可以通过提出的非平衡运输模型来描述……更多是研究。Besides单调分类，替代分类：替代分类：纵向替代性排序和横向替代分类（纵向分类）。这些排序不需要强制改变所提供的沉积物。每种晶粒尺寸的非平衡运输和床表面组成的变化都会使床表面组成的不稳定。在本研究中提出的非平衡运输模型可以描述地层过程。在具有纵向替代分类的流中，床粗糙的纵向变化严重改变了湍流结构，随后悬挂沉积物传输的特征在其上。基于湍流测量值，得出了一个模型来描述由于床剪应力的变化而导致的雷诺压力分布的松弛过程，这是一种具有冲动响应的卷积融合类型。湍流动量交换与悬浮沉积物的湍流转运之间的相似性表明，悬浮沉积物的非平衡浓度分布的描述与为雷诺压力分布制备的弛豫模型。较少的