1997 Fiscal Year Final Research Report Summary
Prediction of Viscous Debris Flow and Its Mitigation
| Project/Area Number |
07044144
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Field |
Natural disaster science
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| Research Institution | Kyoto University |
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Principal Investigator |
TAKAHASHI Tamotsu Kyoto Univ., Disaster Prevention Reserach Inst., Prof., 防災研究所, 教授 (40027230)
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| Co-Investigator(Kenkyū-buntansha) |
OU Gochan Chinese Academy of Science, Inst. of Mountain Disasters and Environment Prof, 成都山地災害環境研究所, 教授
ARAI Muneyuki Meijo Univ., Faculty of Science and Engineering, Assoc.Prof., 理工学部, 助教授 (90103259)
MIZUYAMA Takahisa Kyoto Univ., Graduate School of Agriculture, Prof., 農学研究科, 教授 (00229717)
SUWA Hiroshi Kyoto Univ., Disaster Prevention Research Inst., Assoc.Prof., 防災研究所, 助教授 (00093253)
SAWADA Toyoaki Kyoto Univ., Disaster Prevention Research Inst., Assoc.Prof., 防災研究所, 助教授 (60027258)
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| Project Period (FY) |
1995 – 1997
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| Keywords | viscous debris flow / intermittency / mechanics / material property / occurrence condition / deposition / topographical change / countermeasures |
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| Research Abstract |
The research aimed to make clear the mechanism of flow, the process of occurrence and the method to cope with for the viscous type debris flows. The joint research has been implemented by observing the actial flow in the Jiangjia test field in Yunnan Province, china together with the basic research in the laboratory.
Every time when the Japanse staff members visited the test field, the debris flow occurred and the details of the actuality of the flow were grasped. Different from the stony type debris flow, the viscous type debris flows have happened rather long after the intense rainfall and they have appeared as the numerous surges. From these characteristics a conclusion that each surge has been produced by a small scale landslide has deduced.
The viscous debris flow used to be explained by the Bingham fluid model that attributed the stoppage of the flow between the successive surges to the yield strength of the material. The data of the observation, however, denied the existence of such a strength, and therefore a new Newtonian fluid model was introduced. The mechanism for supporting concentrated solid particles in the laminar Newtonian fluid was made clear and formulae for deposition velocity of the particles and for the resistance to flow were deduced. Thereby, a numerical simulation of the debris flow became possible.
The deatailed survey of the topographical change before and after the debris flow and the examination of the effectiveness of the countermeasures in the actual basins suggested the principle to cope with the viscous debris flows.
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