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Numerical simulation of the Debris Flow Occurred at Izumi City on July 10, 1997.

1997年7月10日和泉市泥石流的数值模拟。

基本信息

批准号：
10680447
负责人：
HASHIMOTO Haruyuki
金额：
$ 2.5万
依托单位：
Kyushu University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10680447/
关键词：
Debris Flows Sediment Flows Natural Disasters Numerical Simulation Sediment Deposition Hazard Map

项目摘要

Debris flow occurred at Izumi city , Kagoshima Prefecture on July 10, 1997, and so 21 people died because of this event. The debris flow was caused by the failure of mountain slope of the angle of 26°. After the slope failure the debris moved down slope of 6.8° and deposited on the alluvial fan of lope angle of 3.7° 〜2.4°. It is important to make debris-flow hazard map of this area as its counter measures. The purpose of this study is to accumulate the knowledge for numerical simulation method of the debris flow.The results obtained in this study are as follows :(1) In order to examine the process of debris-flow termination, experiments of debris flow were made in an open channel with rapid decrease in slope from 4° or 6° to 2°. Bed materials used in the experiments are fine sand with the diameter of 0.17 mm and coarse sand of 0.84 mm. In the case of the coarse sand considerable deposition occurs at the changing point of channel slope. At the same time deposition area extends to the downstream and upstream directions. In the case of the fine sand considerable deposition occurs in the more downstream area from the changing point of channel slope. At the same time deposition area extends to the downstream direction.(2) Numerical simulation of these experiments was made ; the basic equations are the momentum equation and two continuity equations for solid and fluid phases. Sediment transport equation is necessary to solve the basic equations. Two different types of sediment transport equations are used ; one is a bed-load transport equation and the other a total-load transport equation. The result of computation with the bed-load transport equation agrees with the experiments in the case of coarse sand. However the result of computation with the total-load transport equation cannot explain the experimental results in the either case of coarse sand or fine sand.

1997年7月10日，鹿儿岛县泉市发生泥石流，造成21人死亡。泥石流是由26°角山体边坡破坏引起的。坡面破坏后，碎屑沿6.8°坡面下移，沉积在坡面倾角为3.7°~ 2.4°的冲积扇上。制作该地区的泥石流危险区图作为防治措施是十分重要的。本研究的目的是为泥石流的数值模拟方法积累知识。研究结果如下：(1)为考察泥石流终止过程，在坡度从4°或6°迅速减小到2°的明渠中进行了泥石流试验。实验采用的床材为直径0.17 mm的细砂和0.84 mm的粗砂。在粗砂的情况下，河道坡度变化点处发生了相当大的沉积。同时沉积区向下游和上游方向延伸。在细沙情况下，在河道坡度变化点较下游的区域会发生相当大的沉积。同时沉积区向下游方向延伸。(2)对这些实验进行了数值模拟；基本方程是动量方程和固、流两相连续方程。泥沙输运方程是求解基本方程所必需的。采用了两种不同类型的输沙方程；一个是床荷载输运方程，另一个是总荷载输运方程。用床载输运方程计算的结果与粗砂土的试验结果一致。但是，用全荷载输运方程计算的结果不能解释粗砂和细砂的试验结果。