A型梳子壩防治土石流功效之試驗

Experiments on Preventing Debris-Flow by A-type Slit Dam

江永哲(Yung-Cheh Chiang) ； 吳道煦(Daw-Sheu Wu)

《中華水土保持學報》 21卷2期 (1990/11) Pp. 29-43

https://doi.org/10.29417/JCSWC.199011_21(2).0002

摘要

本試驗為明瞭A型梳子壩對於土石流之調節功效，乃利用室內渠槽試驗，探討A型梳子壩開口間隔之設計，對於防治土石流功效之影響。茲將本試驗所得之結果說明如下：1.A型梳子壩之開口間隔b會影響土石流尖峰濃度；開口間隔愈小，則過壩後之土石流濃度愈低。由土石流之尖峰土砂濃度Cp對b／dmax値之迴歸關係式為：Cp = 0.3486（b／dmax）^(0.339259)，r=0.7278^(..)式中，dmax為土石流最大粒徑。2.A型梳子壩之開口間隔b會影響壩體之貯砂效果；由壩體之貯砂率R（％）對b／dmax之迴歸關係式如下：R = 0.414148-0.87954 log（b／dmax），r = 0.8215^(..)3.A型梳子壩之開口間隔b會影響土石流尖峰流量；由土石流尖峰流量Qp和供水流量Qw之比値Qp／Qw對b／dmax值，進行迴歸分析，所得之迴歸關係如下：Qp／Qw = 1.273172 + 0.550243（b／dmax）-0.7185^(..)4.A型梳子壩可分離土石流之粗礫石，而將土石流之集體搬運型態轉化為一般土砂流出狀態；其中dm'／dm對b／dmax之迴歸關係式如下：dm'／dm = 0.6991（b／dmax）^(0.502914)，r = 0.7394^(..)5.當b／dmax之值小於1.5以下，則壩體較顯著之貯砂效果，而當b／dmax小於2以下，則壩體有分離土石流粗礫石之功效。6.在設計A型梳子壩時，若礫石粗細懸殊，宜考慮其分離效果；否則應以貯砂效果為著眼。

關鍵字

土石流 ； 梳子埧 ； 土石流尖峰濃度 ； 狹縫間隔

並列摘要

In order to realize tile effect of the A-type slit dam on controlling debris-flow, Г aimed at investigating how the widths of the slit dam would influence the prevention of debris- flow in laboratory experiments and establishing their relationship. The results of this study were as follows: 1. Different slit widths of A-type dam would influence the peak debris-flow concentration, and the relationship between them can be given by the following regression equation: Cp= 0.3486 (b/d_(max))^(0,339259), r = 0.7278** where d_(max) is the maximum grain-size of debris-flow. 2. The slit width of A-type slit dam would influence the proportion of sediment capacity, and the relationship between them can be given by the regression equation: , R =0.414148 - 0.87954log (b/d_(max)), r =0.8215** . 3. The peak debris-flow discharge is influenced by the slit width of the A-type slit dam, the relationship between Q_p/Q_w and b/d_(max) can be given by the following regression equation: Qp/Qw = 1.273173 +0.550243 (b/d_(max)), r = 0.7185** where Q_p is the peak debris-flow discharge and Q_w is the discharge of water-supplier, 4. Due to the effect of trapping rough gravel of the debris-flow, the A-type slit dam can transfer the type of mass movement of debris-flow into tractive flow, the relationship between d_m'/d_m and b/d_(max) is given by the following regression equation: d_m'/d_m = 0.6991 (b/d_(max))^(0.502914), r =0.7394** where d_m' and d_m are the mean grain-size of the discharged sediment and the experimental sample respectively. 5. The A-type slit dam is more effective in catching sediment when b/d_(max) ≤ 1.5 and in trapping rough gravel of debris-flow when b/d_(max) ≤2. 6. If the difference of diameter between gravel is big, the design of the A-type slit dam is suggested to consider the effect of trapping rough gravel: otherwise to consider the effect of reserving sediment.

並列關鍵字

debris flow ； slit dam ； peak debris flow concentration ； slit width