A Numerical Study on half-three Dimension Debris Flow

• Main Authors: Yang,Maw-Rong, 楊茂榮
• Other Authors: Liu,Ko-Fei
• Format: Others
• Language: zh-TW
• Published: 1996
• Online Access: http://ndltd.ncl.edu.tw/handle/12988179610337380782

碩士 === 國立臺灣大學 === 土木工程研究所 === 84 === Debris flow is composed of grain, sand and water, and occurs in mountainous area where large amount of loose deposit and str- ong run-off can be mixed. Debris flow behaves like nonewtonian fluid, for example, Ba- gnold model is suitable for granular flow and Bingham fluid is applied to mud flow. This research emphasis on fluids which pos- sess a yield stress. From previous researches(Bagnold,1989), the boundary layer is very thin for large scale debris flow, most of flow region is under weak stress area. We assume, debris flow is incompressible fluid. This research neglects erosion, deposition and change of concentration. Firstly, let debris flow through a channel with varying wid- th and bottom, then we can solve all the velocity components. D- ebris flow is found to deposit more in deeper and narrower area. Transmitted and reflected waves are found near narrowing region. After debris flow stops, the bottom becomes smoother. Substracting physical boundary through Tong- Mem map, we use coordinate transformation method which solve Laplace equation w- ith boundary element method, to find flow net for our computati- on. Governing equations are transformed to new coordinate system . The numerical scheme is applied on rectangular, trapezoid, tr- iangular and parabolic channel. Finally, we simulate debris flow at the headwater vallery of Tong-Men.