Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/33447
標題: An Experiment for the Debris Flow Screening Efficiency by the Screening Bar Length of the Plain Screen Device
平面柵柵棒長度對土石流篩分功效之研究
作者: 林彥志
chih, Lin yen
關鍵字: debris flow
土石流
plain screen device
screening ratio
平面柵
篩分比
出版社: 水土保持學系
摘要: 中文摘要 透過性壩中的平面柵的設置,除了能使土石流發生脫水作用而停淤,還可以避免土石流衝擊力造成的損壞及改善上游儲砂空間不足的問題。改良式平面柵在下游處增設分流河道,分離出之細顆粒土砂及水從分流河道引導至下游原河道或安全地區排放,分離之較大礫石則由主流河道運動至預計沉積處。 土石流發生時,水與坡度為其行進動力的重要因子。當其流經平面柵時大部分水被析出,較細顆粒通過柵棒與水一同流出,而較大顆粒則會因為無法通過柵棒停淤柵棒之上,土石流規模較大時,過篩的時間會相對的減少使篩分比下降,由於柵棒長度與篩分比為微幅正相關且有效柵棒長度之增加能使過篩空間增加,延長過篩時間,若能控制土石流流量找出土石流在不同渠床坡度不同柵棒長度過篩的影響,則能分析在柵棒長度因子之作用下,篩分比所呈現之正相關趨勢,並討論當渠床坡度改變時,正相關趨勢之變化情形。 關鍵字:土石流、平面柵、篩分比
ABSTRACT The plain screens can make debris flow dehydration and debris depositing. They can avoid the damage made by direct impaction of the debris flow and improve the problem of insufficient sand-trapping capacity. And the improved plain screens has channels to separate flow at downstream so that the water and fine particles can flow through by-pass to downstream. Then, the coarse cobbles can move along the main channel to the predicted deposit places. With the coming of debris flow, water and slope are the key factors of moving power. For the debris flow moving along the plain screen device, this device will screen out water and fine gravel. Coarse cobbles will block the plain screen device because the cobbles is bigger than the gap of the screening bar. For the bigger debris flow moving along the plain screen device makes the screening time and screening ratio lower. When the screening bar length increase, screening ratio and screening space will become more and more and it can extend the screening time. If we can control the debris flow discharge, we can analyze the tendency of screening ratio with the factor of screening bar length in different channel slope and screening bar length. We can disscuss the change of the tendency when the channel slope changes. Keyword: debris flow, plain screen device, screening ratio
URI: http://hdl.handle.net/11455/33447
Appears in Collections:水土保持學系

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