| Summary: | 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.
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