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研究生:陳柏安
研究生(外文):Chen, Bryan
論文名稱:混合粒徑土砂之土石流剪應力特性研究
論文名稱(外文):Study on the Characteristics of Shear Stress in Debris Flow with Mixed Grain size
指導教授:游繁結游繁結引用關係
指導教授(外文):Yu Fan Chieh
學位類別:碩士
校院名稱:國立中興大學
系所名稱:水土保持學類
學門:農業科學學門
學類:水土保持學類
論文種類:學術論文
論文出版年:1996
畢業學年度:84
語文別:中文
論文頁數:62
中文關鍵詞:土石流剪應力
外文關鍵詞:Debris flowshear stress
相關次數:
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為瞭解土石流之流動應力組成,並進而知悉其流動之各種特性,本
研究藉由室內渠槽之 實驗,以不同粒徑土砂調配成21種試料,實際測定
其流動剪應力,經分析結果而得結論如下 : 1.應變片製作而成之簡易
剪力計,可測得土石流流動之總剪應力,惟受儀器之限制,濾波之 效
應有再改進之必要。 2.段波高度為影響剪應力之重要因子,段波高度愈
大,實測剪應力亦隨之增加,而體積濃度 同樣也有類似之趨勢。
3.實測平均流速與實測剪應力似有負變之趨勢,推測影響剪應力大小應與
速度梯度之大小有 較高相關程度,而並非完全由平均流速之大小所決
定。 4.由動摩擦之觀點而言,土石流之動內摩擦係數隨H/D50之增大而
有增加之趨勢,而隨體積 濃度之增加乃呈減少之趨勢,同時似有隨渠
床坡度增加而增大之傾向;而對於鋼鈑鈑面之 動摩擦係數來說,則隨
渠床坡度之增大則呈遞減之情形,另鋼鈑鈑面之動摩擦係數有隨 H/
D50增加而減緩之情形發生。 5.游之流速推估式,在本實驗中驗證結果
,大體來說尚稱吻合,而高橋之理論式則多所偏估 ,此可能因土石流
體通過測量段時處於加速或減速階段未能有效掌握,使理論推估有所偏
差。 6.實驗中由於包含了土石流段波對床面加糙部份之作用力,導致實
測剪應力較之理論剪應力 為大,對於此一因素之影響或尚有其他應力
作用,可於往後之試驗改進後進一步探討。
The purpose of this paper was going to measure the total
shear stress in order to understand the flowing characteristics
of debris flow. Twenty-one kinds of soil materials which were
composed with different grain size were used to conduct the
flowing experiments in flume channel. And the results were
concluded as follows: 1. A shearmeter which was made with
strain gage could measure the total shear stress during
debris flowing. But the output signals still could not regulated
perfectively because of the restriction of recorder. 2. The
bore height is an important factor to affect the shear stress in
debris flow.Measured shear stress would increase with the
bore height, so does the volumetric concentration. 3.
Velocity had an inverse tendency to the measured shear stress.
The velocity gradient might be play the main role rather
than the velocity to affect the shear stress. 4. In the
viewpoint of dynamic friction, the inner dynamic friction
cofficient would increase with H/D50 and the flume channel
slope but in inverse of the volumetric concentration. For
the surface friction of shearmeter, the friction cofficient
would have the inverse tendency to H/D50 and the flume channel
slope. 5. Comparing with Takashi''''''''s velocity equation, Yu''''''''s
equation might comparatively match with the measured
velocity. The measured velocity could not match well with
the theoretical velocity, because some parts of observations for
flowing velocity were not in the state of steady flow. 6.
Synthetic roughness on the channel bed made the shear stress
higher than the theoritical shear stress. The observed shear
stresses could not confirm whether the real shear stress
was or other stress effects were contained.
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