梳子壩流量公式之研究

The Study of Flow discharge formula on slit dam

陳盈男(Ying-Nan Chen)

指導教授 ： 黃宏斌

共同指導教授 ： 陳增壽(Tzen-show Chen)

國立臺灣大學/生物資源暨農學院/生物環境系統工程學研究所/碩士(2005年)

https://doi.org/10.6342/NTU.2005.10386

摘要

本研究蒐集國內、外梳子壩流量計算相關設計案例及研究文獻，以流體力學及渠道水力學之理論為基礎，利用連續方程式、能量方程式及動量方程式，並參考計算橋墩能量損失之方法，推導出水流經梳子之能量損失，並考慮斷面束縮、梳子壩開口間距及梳子壩開口數等因子，推導出一適合梳子壩之流量推估公式，試驗分成水深過梳子與水深未過梳子兩部分，分別各設計四種不同梳子間距、三種不同跌水及河床坡度、每個坡度設計四種不同之流量以進行水理試驗，利用所得之360組流量數據進行分析，提出下列主要結果：
1. 在水深過梳子時或水深未過梳子兩種狀況下，能量消減程度皆會隨著跌水變高而跟著增加，水深此因子對於能量消減程度之改變則沒有一定之關係。
2. 水深大於梳子時，傳統防砂壩公式無法代表梳子壩之流量，依本研究之結論，流量公式需乘上一修正係數，才能切合實際情形，得到之關係式如下：
，其中R2=0.88
3. 經由本研究之分析探討，在水深未過梳子情況下可得到一梳子壩之流量推估公式如下：
，其中R2=0.87
式中：Q=梳子壩之流量（cms）； B=壩寬（m）；
b n =梳子間距總長（m）；S=河床坡度
h=觀測水頭（m）；n=梳子壩柱數目
g=重力加速度（m/s2）

關鍵字

梳子壩 ； 水槽試驗 ； 能量損失

並列摘要

The project proposes to collect the international and domestic literatures and design cases associated with flume experiments to derive the flow discharge model of slit dams and their spillways. The model utilizes the fundamentals of fluid mechanics and open channel mechanics. It employs continuity equation, momentum equation, energy equation, and the method of calculating the energy loss of piers to derive the energy loss associated with the flows between slit dams. The model also takes into account of section contraction, the distance between dams, and the number of dams to formulate the slit dam discharge equation. The flume experimental divides into the flow depth over comb and the flow depth not yet over two parts, setup involves four various distances between the dams and discharge for every slope, three different drops and bed slopes. The 360 set data obtained is analyzed to propose capital result model.
1. In the flow depth over comb or the flow depth not yet over two situaion, energy reduced rate will all be followed to increase as become high to drop, the factor of flow depth is no certain relation in this change to the thing that energy reduced rate.
2. For discharge formula of dam in soil and water conservation manual used in Taiwan area, by way of this project that there is phenomenon underestimated seriously to emerge in discharge formula estimating the slit dam with this discharge formula, it is unsuitable to use for what has been designed the slit dam on the engineering, need to do a revision of Cd value, could be geared to actual circumstances the situation, the relational formula received is as follows:
，which R2=0.88
3. When the flow depth are higher than comb, the formula of traditional check dam can’t represent the discharge of slit dam, with the result of this study, the discharge formula must multiply a correct coefficient to conform to realize situation, get a relationship formula as follows:
，which R2=0.87

Where, Q= the discharge of slit dam(cms); B=dam width(m)
b=comb interval length(m) ;S=bed slope
h=observing water head(m) ;n=numbers of comb
g=acceleration of gravity

並列關鍵字

slit dam ； flume experiment ； energy loss

參考文獻

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29. 連惠邦、柴鈁武（1998），土石流防治工法之梳子壩開口寬度設計模式，中華水土保持學報，29(3),175~187。

30. 連惠邦、柴鈁武、林忠義（1998），梳子壩對土石流防治效率之實驗研究，中華水土保持學報，29(2),127~139。

26. 柴鈁武、連惠邦（1997），切口式防砂壩對土石流之攔擋效率，中華水土保持學報，28(4),341~451。

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