Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/15123
標題: 帶工法對投潭水流行為及沖刷特性之影響
The effect on Behavior of free Over-Fall Flow and Local Scouring Downstream of Sabo Dam using Fixed Apron
作者: 宋爾寧
Song, Er-Ning
關鍵字: Fixed Apron
帶工法
出版社: 土木工程學系
摘要: 摘 要 鑑於台灣地區防砂壩等水工結構物之毀損,大多由於投潭水淘刷毀壞壩體下游保護工,進而上溯影響壩基之穩定所造成。本文參酌前人相關研究成果,進行堰埧投潭水流對下游河床沖刷之研究。首先在堰壩下游無保護工下進行不同流況之沖刷試驗,以瞭解投潭水流造成沖刷坑之沖擊行為及沖刷坑特性。再配合帶工構造物之設置,研究其對下游床面之保護功效,以及變換不同渠坡探討坡度效應對堰壩投潭水局部沖刷之影響,同時並由力學的觀點,剖析投潭水帶工法之消能行為。 經試驗觀察及結果分析後,發現帶工設置會使投潭水流行為接近定床時的水理機制。從沖刷特性方面的試驗結果,諸如最大刷深減小、沖刷體積量會變小與沖刷現象會較遠離壩址,均可表彰帶工的設置有消減投潭水流沖刷潛能,以及抵擋水流垂向沖擊力而改善沖刷現象之功能。又隨著渠床坡度的變陡,投潭水流的沖刷潛能及沖擊力會變大,導致泥砂顆粒較易被水流起動沖刷,因而使得沖刷現象加劇。
ABSTRACT Most failures of hydraulic structures (such as Sabo dam) in Taiwan were due to the scouring of downstream protection works. According to the past research of other scholars and the experiments conducted here at the laboratory of the NCHU (National Chung-Hsing University), this study is to investigate the effect of local scouring by free over-fall flow on the fixed apron, which is constructed on downstream. Starting with the experiments without the fixed apron to see the behavior of free over-fall flow and the characteristics of scouring hole on downstream bed, then with the fixed apron to investigate how them protect the downstream bed. At last, change the flume-slope to see how it affects the scouring. According to the experimental results, the behavior of free over-fall flow is close to the situation of fixed bed, the maximum scouring depth and the scouring volume of the scouring hole decrease; the scouring also farther from the Sabo dam. Those show that the fixed apron could decreases the scouring energy and the force of free over-flow effectively to protect the element of Sabo dam. When the flume-slope is steeper, the scouring energy and the force of free over-flow are larger, and it easier to transmit the sand downstream, and the scouring become even worse.
URI: http://hdl.handle.net/11455/15123
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