Critical conditions of bed sediment entrainment due to debris flow
Critical conditions of bed sediment entrainment due to debris flow
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DOI：
10.5194/nhess-4-469-2004
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发表时间：
2004-08
影响因子：
4.6
通讯作者：
M. Papa;S. Egashira;T. Itoh
中科院分区：
文献类型：
--
作者：
M. Papa;S. Egashira;T. Itoh
抽象的。本文通过水槽试验、数值分析和量纲分析，描述了泥石流床沙的卷吸特性。通过水槽试验研究了床沙尺寸对侵蚀床上泥石流的侵蚀速率的影响。试验结果表明，虽然侵蚀速率随泥石流含沙量的变化而变化，但侵蚀速率随泥沙粒度的增大而单调减小。为了评价泥沙夹带的临界条件，引入了一种测量有效床面剪应力的长度标尺。有效床面剪应力定义为床面总剪应力减去屈服应力。结果表明，用有效床面剪应力代替通常的床面剪应力，可以很好地用Shields曲线来评价临界卷吸条件。
Abstract. The present study describes entrainment characteristics of bed material into debris flow, based on flume tests, numerical and dimensional analyses. Flume tests are conducted to investigate influences of bed sediment size on erosion rate by supplying debris flows having unsaturated sediment concentration over erodible beds. Experimental results show that the erosion rate decreases monotonically with increase of sediment size, although erosion rate changes with sediment concentration of debris flow body. In order to evaluate critical condition of bed sediment entrainment, a length scale which measures an effective bed shear stress is introduced. The effective bed shear stress is defined as total shear stress minus yield stress on the bed surface. The results show that critical entrainment conditions can be evaluated well in terms of Shields curve using the effective bed shear stress instead of a usual bed shear stress.