防砂壩之水理特性研究

Study on Hydraulic Characteristic of Sabo Dam

林傳茂(Chawn-Mouwn Lin) ； 黃宏斌(Hung-Pin Huang)

《中華水土保持學報》 25卷4期 (1994/12) Pp. 231-237

https://doi.org/10.29417/JCSWC.199412_25(4).0006

摘要

本研究之目的在探討防砂壩在壩後不同坡度及各種淤積情形下，其水理特性變化，並與水土保持局使用之流量公式加以分析比較。因此，本研究將藉著水槽試驗，分別探討在固定床面糙度下，上游河床坡度變化與淤積高度之不同，對壩上游狀況和流量估算之影響。本研究以梯形防砂壩，於一公尺寬水槽中從事試驗，試驗項目依壩後淤積情形分無淤積、半淤滿與全淤三種；並分別依四種坡度，0〜0.04，六種試驗流量，0.0066〜0.0579 cms，進行試驗。根據72組有效數據之分析，提出下列主要結果：（1）防砂壩上游淤積高度之增加，將相對減小有效壩高，壩上游水深降低。（2）壩上游河床坡度之增大，可促使壩上游水深降低；並隨上游淤積高度之增加，坡度變化對水深影響增大。（3）由於上游河床坡降與淤積高度之增加，將改變壩上游水深降低，經由流量公式所推估流量，將呈現低估現象。（4）壩上游淤滿時，堰流公式對於壩流量之推估將會造成極大誤差，而且曼寧公式亦需以修正係數修正後方能使用。（5）對於臺灣地區使用之防砂壩流量公式，當無淤積且觀測值h/p大於0.4，或半淤滿情形且觀測值h/p大於0.63時，均有推估流量偏低之趨勢，需以適當之h/p函數之修正値修訂其流量係數。

關鍵字

防砂壩 ； 水理特性

並列摘要

The objective of this study was to explore the variation of hydraulic characteristic of sabo dam with the various deposit slope and height, as well as the comparison of experimental data with the calculating result by means of discharge formula used by Soil and Water Conservation Bureau. Hence, this study carried out the flume experiment to, with constant bed roughness, get the effect of deposit slope and height to upstream flow condition and estimation of discharge. Associated with the trapezoidal type of sabo dam in one meter wide of flume, there were three series of experiments to be conducted in this study. That is, no deposit, half deposit and full deposit. With four slopes ranging from 0 to 0.04, six discharges from 0.0066 to 0.0579 cms, this study analyzed 72 sets of available data and got following results: (1) That the increase of deposit height in upstream zone of sabo dam would result in decrease of available dam height and approached water depth. (2) The increase of bed slope in upstream zone of sabo dam would cause the decrease of approached water depth. And, with increasing deposit height, the effect of change of slope to water depth would be more significant. (3) The decrease of approached water depth due to the increasing deposit slope or height would underestimate flow discharge calculated by discharge formula. (4) In case of full deposit, the estimation of weir formula would get big discrepancy. And, Manning formula should be modified by correction factor before estimating discharge of trapezoidal type of sabo dam. (5) For discharge formula of sabo dam used in Taiwan area, the computing result, in case of no deposit and h/p＞0.4, as well as half deposit and h/p＞ 0.63, would be underestimated and could be improved by some correction factors functioned of h/p.

並列關鍵字

Saba Dam ； Hydraulic Characteristic