梳子埧調節土石流功效之試驗

Experiments on Controlling Debris-flow with Slit Dams

林裕益(Yuh-Yih Lin) ； 江永哲(Yung-cheh Chiang)

《中華水土保持學報》 19卷1期 (1988/05) Pp. 40-57

https://doi.org/10.29417/JCSWC.198805_19(1).0004

摘要

梳子埧係屬開放式防砂埧的一種，其設計主要是依據溪床質粒徑分佈狀況，以決定狹縫間距之大小。本文爲瞭解梳子埧對野溪上游土石流之調節功效，乃擬利用室內渠槽試驗，探討梳子埧抑制土石流之有效狹縫間距，以供有關單位設計梳子埧時之參考。茲將本試驗結果分析所得之結論，列擧如下：（1）梳子埧狹縫間距b之大小，會影響土石流尖峰濃度C，；亦即土石流尖峰濃度對b/d_(max)對數成線性關係，其二者之廻歸關係式如下：C_p = 0.2485 +0.1819 log（b/d_(max)）r = 0.7428 **式中，d_(max)爲土石流最大粒徑。（2）梳子埧狹縫間距b之設計，若符合b / d_(max) ≦1.7的條件，則埧體便具有顯著之攔砂功效。（3）梳子埧可消減土石流尖峰流量，具調節土石流流量之功效。其中，Q_p / Q_w對b/ d_(max)成線性關係，廻歸式如下：Q_p / Q_w = 1.6080 + 0.1713（b/d_(max)）r = 0.8286 **式中，Q_p，爲土石流尖峰流量，Q_w爲供水流量。（4）當b / d_(max)值小於2.0時，則梳子埧即可將土石流集體流動型態轉變成一般土砂流動狀態；且隨b / d_(max)值減小，其分離土石流粗礫石之功效愈顯著。

關鍵字

梳子埧 ； 土石流 ； 狹縫間距 ； 土石流尖峰濃度

並列摘要

Experiments on Controlling Debris-flow with Slit Dams Slit dam 15 one kind of open dams and the design of it is primarily according to the grain-size distribution of stream bed, which can decide the size of slit width. In order to realize the effect of the slit dam to debris-flow, this study perform laboratory experiments and discuss the best design of slit width. From the results of this study, the writer hope to offer some suggestions for the authorities that would be appropriate to prevent and control the similar disasters In the future. Now the conclusions from the analysis of this experimental results were obtained as follows: 1) The peak debris-flow concentration Cp will be Influenced by the slit Width; that is, there Is the linear correlation between the peak debris-flow concentration and .the logarithm of b/d max. The regression equation is Cp =0.2485 +0.1819 log (b/d max) r = 0.7428** where d max is maximum grain-size of debris flow. 2) If the design of the silt width can meet the qualification of b/d max ≤; 1.7, the dam will have obvious effect of keeping sediment away. 3) The peak debris-flow discharge can be decreased by a slit dam; that Is, It Is able to adjust debris-flow discharge. Within It, there Is the linear correlation between Qp/Qw and b/d max. The regression equation is Qp/Qw = 1.6080 +Q.1713 (b/d max) r = 0.8286** where Qp Is peak debris-flow discharge and Qw is discharge of water-supply. 4) When the value of b/d max is less than 2.0, slit dam can transfer the type of mass movement of debris-flow Into that of tractive flow. Moreover the effect of trapping rough gravel of the debris-flow Is getting obvious with the decreasing of the value of b/d max.

並列關鍵字

Slit dam ； Debris-flow ； Silt Width ； Peak debris-flow concentration