顆粒外形對顆粒體在滑坡道流動行為之影響及內部性質之探討

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Title:	顆粒外形對顆粒體在滑坡道流動行為之影響及內部性質之探討
Authors:	林昊勳;Lin, Hao-Hsun
Contributors:	機械工程學系
Keywords:	離散元素法;顆粒體崩塌;傳輸性質;內部性質;摩擦啟動因子
Date:	2019-11-08
Issue Date:	2020-01-07 14:39:34 (UTC+8)
Publisher:	國立中央大學
Abstract:	本研究使用離散元素法(Discrete Element Method, DEM)模擬三種質量相同但形狀不同(球形、雙球形及三球形)的顆粒體於一傾斜滑坡道自由崩塌之流動行為，並探討顆粒形狀對流動行為的影響，觀察三種顆粒體在滑動及沉積靜止時的外觀及其對應的物理性質。研究結果顯示球形顆粒體堆積高度較低且沉積的範圍較為廣泛，雙球形及三球形顆粒體堆積高度較高且較集中，顆粒間互鎖效應(interlocking effect)的強度依次為: 三球形顆粒體>雙球形顆粒體>>球形顆粒體。球形顆粒體在運動中易於滾動，整體運動速度較快，碰撞耗能比例較另外兩者更高，雙球形及三球形顆粒體外形較易互鎖，由摩擦主控著耗能及運動行為。雙球形及三球形顆粒體在運動過程中粒子體積佔有率及平均配位數較球形顆粒體大，而在沉積靜止時則是球形顆粒體較大。球形顆粒體在運動中的平均接觸力最大，而在沉積靜止時則為最小。研究結果進一步顯示顆粒體在運動過程中並非全然是滑動摩擦，同時也存在滾動摩擦。雙球形及三球形顆粒體接近滑動摩擦的比例皆較球形顆粒體高，數值最高的情況發生在三球形顆粒體中顆粒與牆壁的接觸，但也僅佔據約整體的70%。;The aim of this study is to investigate the gravity-driven free surface flow of granular avalanches over complex basal topography by using Discrete Element Method (DEM). Three different kinds of particle shape are used in the study, that is, spherical, double-spherical and triple-spherical. The influence of particle shape on the flow behavior is explored. Numerical results show that the particle interlocking effect follows the sequence: triple-spherical > double-spherical >> spherical. The spherical granules show a low packing height and a wide range of deposition, while the double-spherical and triple-spherical granules show a high packing height and a narrow range of deposition. The spherical granules intend to rotate during avalanche, move faster, and exhibit higher energy consumption from collision mechanism. The double-spherical and triple-spherical granules are easier to interlock, and the energy dissipation is mainly dominated by friction. The double-spherical and triple-spherical granules show higher solid fraction and coordination number during avalanche, while the spherical granules show more densely packed configuration at settlement. Not only sliding friction but also rolling friction occurs during avalanche. The percentage close to sliding friction of the double-spherical and triple-spherical granules is larger than that of spherical granules. Only 70% of particle-wall contacts in triple-spherical granules, the highest percentage, can attain sliding friction.
Appears in Collections:	[Graduate Institute of Mechanical Engineering] Electronic Thesis & Dissertation

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