- 期刊
矩形防砂壩流量公式之研究
Discharge Formula for Retangular opening Check Dam
摘要
本研究旨在探討現行防砂壩上游未淤積泥沙時，其溢壩水流流量公式之適用性，並據以提出適當之修正公式，提供防砂壩設計技術準據之參採。研究結果顯示，矩形溢洪口防砂壩溢壩水流所採行之流量公式，因僅適用於溪床水平且斷面無束縮之流況，當溪床坡度逐漸陡化或溢洪口斷面逐漸束縮時，計算流量與實際流量間產生了顯著的偏差，惟經引入溪床坡度及斷面束縮兩修正因子後，計算流量與實際流量間的偏差現象可以獲得明顯地改善。同時，本文也提出了形狀因子，將梯形、矩形及三角形等溢洪口斷面之流量公式予以整合。這樣，綜合考量溪床坡度，斷面束縮及形狀等三個因子之溢壩水流流量公式，可表爲Q = 0.35 b_u（2 + 3χ）[λtanθ]^(-2.038)h^(1.5 [1-0.006(1/λ-1)])式中，Q =溢壩水流流量（cms）; b_u =水面寬度（m）：χ=形狀因子(=b_o/b_u，b_o爲壩頂寬度）；溪床傾角θ=0°~7°；斷面束縮因子λ= b/W = 0.1~1.0；b=溢壩水流均寬[=（b_o +b_u）/2]。
並列摘要
As reference for design criterion, the main purposes of this study were to investigate the feasibility of current overflow discharge formula for check dam and to provide appropriate modification of the formula, if necessary. Based on our research results, the current formula only applies for the check dam with rectangular opening under the conditions of horizontal channels and non-contraction sections. Significant bias between calculated and observed discharges appears when either of these conditions is violated. However, the bias will be decreased significantly by introducing the factors of channel slope and section contraction. Besides, three discharge formulas for different openings (i.e., trapezoid, rectangular, triangular) were integrated into one single formula by the shape factor such that a comprehensive formula considering factors of channel slope, section contraction, and opening shape is represented as: Q = 0.35 b_u（2 + 3χ）[λtanθ]^(-2.038)h^(1.5 [1-0.006(1/λ-1)]) where Q is the overflow discharge of sabo dam; b_u is the width of channel: χ is the shape factor(=b_o/b_u, where b_o is the width of check dam). Channel slope θ ranges from 0 to 7 degrees while section contraction factor, λ=b/W ranges from 0.1 to 1.0. The average width of overflow, b= (b_o+ b_u)/2.