溪床礫石堆積在逕流作用下產生土石流之渠槽實驗; Experimental Study of debris flow induced by runoff at the gravel deposition riverbed

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Title:	溪床礫石堆積在逕流作用下產生土石流之渠槽實驗;Experimental Study of debris flow induced by runoff at the gravel deposition riverbed
Authors:	徐羽平;Yu-ping Hsu
Contributors:	土木工程研究所
Keywords:	顆粒流;土石流;速度剖面;潰壩;Velocity profile;Dam failure;Debris flow;Granular flow
Date:	2010-07-30
Issue Date:	2010-12-08 13:35:53 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究進行之礫石型土石流之渠槽實驗，透過高速攝影機捕捉顆粒運動之影像，及Matlab 程式進行顆粒流場之分析。本研究以Voronoi Patterns 方法獲得流場內顆粒之速度向量，藉此分析顆粒體的速度分佈及流動特性，實驗之特色在於堆積顆粒在上游受水的壓力與潤滑作用發生群體運動，一直到產生穩定的顆粒流體化狀態的過程中，在前端顆粒群體與水的混合狀態是不均勻的，且顆粒將集中於前方具有隆起的前端，前後段的顆粒濃度也不相同，並與現地土石流具有類似之特徵。在實驗中將改變上游供水速率和渠槽角度，分析上視和側視的速度剖面，並與前人之實驗與數值結果相比較，顯示此種的顆粒運動接近於Bagnold 流變學的條件，並與礫石型土石流有相同的特性，進而比較水量與土石流型態的關係。 In this study, we setup a flume experiment to simulate the initiation of stony debris flow. We use high speed camera to capture the motion of particles, and Matlab to analyzing the flow field. We get the velocity vector in the flow field by Voronoi Patterns method. By the method, we can analyze the velocity distribution and the flow characteristics. In the experiment, the accumulated particles at upstream are saturated water reduces the friction resistance, so the particles will move entirely. The flow process is non-uniform, combining water and particles, in the snout. The particles accumulated in the snout are not saturated and the wave front becomes a bulb. The characteristic of bulbous wave is similar with the field debris flow. In the experiment, we change either the angle of flume or the flow rate to analyze the velocity profiles from both top view and side view. Comparing with the reference, the velocity profile can be described by Bagnold theory, and then we also show the relationship between peak flow rate of the debris flow and the type of dams and inflow.
Appears in Collections:	[Graduate Institute of Civil Engineering] Electronic Thesis & Dissertation

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