Journal of the Japan Society of Erosion Control Engineering
Online ISSN : 2187-4654
Print ISSN : 0286-8385
ISSN-L : 0286-8385
Original Articles
Numerical simulation for run out process of large-scale debris flow focused on fine sediments behaviors -application for debris flow triggered by a deep catastrophic landslide-
Yuki NISHIGUCHITaro UCHIDATadanori ISHIZUKAYoshifumi SATOFUKAKana NAKATANI
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JOURNALS OPEN ACCESS

2011 Volume 64 Issue 3 Pages 11-20

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Abstract

Deep catastrophic landsides have triggered large-scale debris flows that have had serious impacts on humans. Therefore, it is important to predict the run-out process of debris flows and to identify debris flow hazard areas. Here we developed a new technique for simulation of large-scale stony debris flows. Debris flows have been modeled by mixture of solid and fluid phases. In this study, we assumed that fine sediment in debris flows behaves as fluid phase rather than solid phase. Based on this hypothesis, we developed new methods to evaluate key parameters to simulate largescale debris flows, such as sediment concentration, fluid density, and representative particle diameter and modified the continuity equation for sediment. We also proposed a new process-based method for determination of hydrographs at the lower end of the landslide scar. We conducted detailed field surveys of the past debris flow in Atsumari river in Minamata city and used topographic data from LiDAR imagery, porosity measurements of soil and weathered bedrock and the grain size distribution of the debris flow sediments to test our model. Using these new data and methods, we conducted numerical simulations of the past debris flow, which reproduced well the observed erosional and depositional pattern.

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© 2011 Japan Society of Erosion Control Engineering
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