梳子壩對土石流防治效率之實驗研究

An Experimental Study on Controlling of Debris Flow with a Slit Dam

連惠邦(Hui-Pang Lien) ； 柴鈁武(Fang-Wu Tsai) ； 林忠義(Chung-Yi Lin)

《中華水土保持學報》 29卷2期 (1998/06) Pp. 127-139

https://doi.org/10.29417/JCSWC.199806_29(2).0005

摘要

本研究以貯砂效率及過壩泥砂體積濃度比兩個參數評估梳子壩對土石流防治之效率，並通過土石流固液兩相質量守恆定律及渠槽試驗方式，建立了兩個參數間的半經驗公式P=1-0.9 R(1-C_(da))/(1-R C_(da))結果證實，上式可以表徵土石流經梳子壩攔擋之後，其泥砂體積濃度和攜出土砂數量的減少程度。式中，P：貯砂效率; R：泥砂體積濃度比（= C_(db)/C_(da)，C_(db)爲土石流過壩後之泥砂體積濃度）; C_(da)：土石流臨前泥砂體積濃度。其中，泥砂體積濃度比與壩體開口寬度相關，若以相對寬度及狹縫密度表示壩體開口寬度之變化時，則由迴歸分析可得土石流過壩泥砂體積濃度比之經驗方程式爲R = 0.144 ln（b / d_m）+1.06 ln（Σb / B）+0.797式中，b / d_m：相對寬度（=1.34~13.98）;Σb/ B：狹縫密度（= 0.45~0.85）。

關鍵字

梳子壩 ； 土石流 ； 貯砂效率 ； 泥砂體積濃度

並列摘要

Based on the conservation of mass principle for solid and liquid in flow and numerous flume experiments, the present study indicates that the dimensionless parameters of numerous flume the dam trap efficiency and the rate of volumetric sediment concentration in a debris flow can reflect the volumetric sediment concentration and the reduction of the sediment after the flow passes through the dam. This semi-empirical expression can be written as P=1-0.9 R(1-C_(da))/(1-R C_(da)) where P= trap efficiency; C_(da)= sediment concentration of debris flow before being passed through the slit-dam, R =ratio of sediment concentration (=C_(db)/C_(da), C_(db), sediment concentration of debris flow after being trapped in the slit dam). From the equation, we realize that the ratio of sediment concentration by volume, relative to the opening width and slit density are closely related, which can be formulated as follows: R = 0.144 ln（b / d_m）+1.06 ln（Σb / B）+0.797 in which b/dm= relative opening width; Σb/B =slit density. The result of the experiment shows that the wider the opening width of the slit dam, the higher is the solid volume concentration of the debris flow after it is trapped in the slit dam.

並列關鍵字

slit-dam ； debris flow ； trap efficiency ； sediment concentration