Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/34097
標題: 土石流平面柵分流效率之試驗研究
An Experiment of Separating Efficiency on the
作者: 張繼儒
關鍵字: plain railing device;平面柵;soil halting factor;土砂滯留因子
出版社: 水土保持學系
摘要: 
The plain railing device has many steel I-beams mounted on the two consecutive check dams. Also there is an angle between the railing bar and the channel. The device can separate the coarse cobble and water when debris flow passes through it. In order to prevent the debris flow remixing, the channel is divided into main channel and by-pass. The coarse cobble can move above the I-beam screen and deposit in the main channel. The fine particle and water will drop through the I-beam screen and flow to the downstream in the by-pass.
By changing the height difference of two check dams and the railing bar length, there will be different condition of the railing slope. One purpose of this experiment is to analyze the relationship between the rate of separating coarse cobble and the railing slope in different railing bar length. Another purpose is to find out the reasonable soil halting factor to satisfy the expected rate of separating coarse cobble. At last we have to decide what kind of I-beam and what size of railing interval should be used in some cases at a job site. The result of this experiment are described as follows:
1.There is a repeated phenomenon of move and stop in three conditions of railing bar length, when the debris flow moves through the device with a gentle slope. The phenomenon is more obvious when the railing bar length is longer.
2.When the slope of the railing bar is between 30 and 40 degrees, the rate of separating coarse cobble is between 1 and 2. It is confirmed to the expected railing condition.
3.When the soil halting factor is between 5 and 10, the rate of separating coarse cobble is also confirmed to the expected railing condition.

平面柵是將數十根具有間隙之H型鋼,放置於兩座相鄰且具有高差之防砂壩上,使H型鋼產生一順坡之角度,進而讓流經其上之土石流產生土石分離效果。並設置主流河道與分流河道,使分離出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,以防土石流有再混和之虞。
本實驗藉由改變上下游壩之高差及鋼棒長度,使平面柵之坡度產生變化,期能了解在不同的鋼棒長度下,土砂分流比和裝置坡度之間的關係。並期能找出合理之土砂滯留因子以滿足所預計之土砂分流比。最後藉由探討平面柵於現場施做的狀況,以決定所應該使用之型鋼型號及鋼棒間距大小。而將所得之結果經整理後如下所列:
1.當平面柵之坡度小時,土石流流經三種鋼棒長度均會發生流動、停積、再流動、再停積之重複現象,而此種現象在鋼棒越長時越明顯。
2.當裝置坡度介於30度~40度之間時,所得之土砂分流比介於1~2之間,和預計之分流狀況相符。
3.當土砂滯留因子集中於5~10之間時,其土砂分流比和預計之分流狀況相符,也就是可藉由調整裝置之坡度及鋼棒長度,而使得土砂滯留因子為所需之值,以達到預計之土砂分離效果。
URI: http://hdl.handle.net/11455/34097
Appears in Collections:水土保持學系

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