Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/33549
標題: 混合粒徑土砂之土石流剪應力特性研究
Study on the Characteristics of Shear Stress in Debris Flow with Mixed Grain size
作者: 陳柏安
Chen, Bryan
關鍵字: Debris flow
土石流
shear stress
剪應力
出版社: 水土保持學類
摘要: 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.
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。
URI: http://hdl.handle.net/11455/33549
Appears in Collections:水土保持學系

文件中的檔案:

取得全文請前往華藝線上圖書館



Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.