Dam break flows and resulting river bed erosion can have disastrous impacts on human safety, infrastructure, and environmental quality. However, there is a lack of research on the mobility of non-uniform sediment mixtures resulting from dam break flows and how these differ from uniform sized sediment. In this paper, laboratory flume experiments revealed that coarse and fine fractions in non-uniform sediment had a higher and a lower bed-load parameter, respectively, than uniform sediments of the same size. Thus, the finer fractions were more stable and the coarser fractions were more erodible in a non-uniform bed compared to a uniform-grained bed. These differences can be explained by the hiding and protrusion of these fractions, respectively. By investigating changes in mobility of the mixed-size fractions with reservoir water levels, the results revealed that at low water levels, when the coarser fractions were only just mobile, the bed-load parameter of the finer fractions was higher than the coarser fractions. The opposite was observed at a higher water level, when a significant proportion of the coarsest fractions was mobilized. The higher protrusion of these grains had an important effect on their mobility relative to the finer grains. The transported sediment on these mixed-sized beds was coarser than the initial bed sediment, and became coarser with an increase in reservoir water level.

溃坝流量和由此引起的河床侵蚀可能对人类安全，基础设施和环境质量造成灾难性影响。但是，关于由溃坝水流引起的非均匀沉积物混合物的流动性以及这些与均匀大小的沉积物有何不同的研究尚缺乏研究。在本文中，实验室水槽实验显示，与相同大小的均匀沉积物相比，非均匀沉积物中的粗颗粒和细颗粒分别具有更高和更低的床荷参数。因此，与均匀颗粒床相比，在非均匀床中较细的馏分更稳定，而较粗的馏分更易腐蚀。这些差异可以分别通过这些部分的隐藏和突出来解释。通过调查混合尺寸馏分的迁移率随储层水位的变化，结果表明，在低水位下，当较粗的馏分仅处于流动状态时，较细馏分的床载参数高于较粗的馏分。当较高比例的最粗级馏分动员时，在较高的水位下观察到相反的情况。这些晶粒的较高突起相对于较细的晶粒对其迁移率具有重要影响。这些混合床的沉积物比初始床的沉积物更粗，随着储层水位的增加而变粗。这些晶粒的较高突起相对于较细的晶粒对其迁移率具有重要影响。这些混合床的沉积物比初始床的沉积物更粗，随着储层水位的增加而变粗。这些晶粒的较高突起相对于较细的晶粒对其迁移率具有重要影响。这些混合床的沉积物比初始床的沉积物更粗，随着储层水位的增加而变粗。