Mechanics of Debris Flow Over a Rigid Bed
Kuniaki Miyamoto* and Yuki Tsurumi**
*Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Ten-no-dai, Tsukuba City, Ibaraki 305-8572, Japan
**CTI Engineering Co., Ltd., 1047-27 Onigakubo, Tsukuba, Ibaraki 300-2651, Japan
Up to the middle of the 20th Century, debris flow was a little understood phenomenon. Since then, much has been done to understand it, including observations, experiments, and theoretical considerations. Studies on constitutive equations contributed much to understanding debris flow. These include a constitutive equation set proposed by Egashira, et al. that seamlessly explains a wide range of sediment-laden flow from debris flow to typical bed-load laden flow. These results mainly considered flow over erodible beds, with little systematic study on those over rigid beds. Using the constitutive equation set, we classify the regime for debris flow over rigid beds, and the characteristics of low concentration flow are discussed. Result suggest that some nondimensional criteria characterize the flow regime. While consider the low concentration regime is not enough to predict particular flows yet, it gives us an approach to understand the flow mechanism.
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