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題 名 | 防砂壩壩體移除之模型試驗--以七家灣溪一號壩為例=Model Experiment on the Check Dam Removal: A Case Study of Chi-Chia-Wan Creek Dam NO.1 |
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作 者 | 王傳益; 葉昭憲; 鄭人豪; 段紀湘; 呂其倫; | 書刊名 | 水土保持學報 |
卷 期 | 42:4 2010.12[民99.12] |
頁 次 | 頁423-437 |
分類號 | 443.92 |
關鍵詞 | 防砂壩; 槽偏量; 最大沖刷深度; Check dam; Horizontal channel trough-line shifting; Maximum scour depth; |
語 文 | 中文(Chinese) |
中文摘要 | 台灣河川坡陡流急,豐枯季節流量差異大,因此河床沖淤變化劇烈,加上橋墩基礎之阻水 作用下,產生局部沖刷,威脅到橋樑的安全。因此瞭解橋墩局部沖刷機制,提出適合之沖刷深 度推估公式,成為當前重要課題。 研究結果顯示,於各評鑑標準下,遺傳演算法(GA, Genetic Algorithms)產出結果之精度絕 大部分優於傳統迴歸方法(Kothyari)。而各項評鑑標準所得之最佳公式與傳統迴歸方式比較其線 性關係及判定係數後,結果顯示以評鑑標準為MAPE 時,GA 所搜尋之優化解於全局搜尋及驗 證與預測上,均較其他評鑑標準準確,其中又以MAPE3 推估所得之結果精度最佳,未來可利 用該式推估均勻橋墩之沖刷深度。 GA 可在一種相對較簡單且穩定的模式中建立,使用遺傳演算法可以有效推估橋墩的沖刷 深。發展GA 只需克服部分困難即可解決許多複雜的問題,且GA 之執行時間較傳統複迴歸分 析方法更為省時。此外,本研究新增各種不同文獻資料做驗證,證明GA 演算結果具適應性及 可靠性。 |
英文摘要 | Check dam is one of the most common sediment prevention structures for rivers in Taiwan. Its main functions are to intercept the coarse sediments, regulate sediment transportation, prevent erosions and restrain the debris flow. However, it also causes a great influence to the river ecosystem. In recent years, check dam improvement becomes a very important issue due to the bank safety and river ecological restoration considerations. This study is aimed to investigate the effect of the improvement of deposit check dam on riverbed stability and habitat variation. The check dam No. 1 of Chi-Chia-Wan Creek is selected as the research target to evaluate various dam removal cases by using hydraulic experiments to understand riverbed stability before and after dam removal. The improvement cases included the removals of the left, middle, and right parts of the dam under usual flood flow Q2 and the 50 years flood flow Q50. To fulfill the riverbank safety requirement, this research provides appropriate dam removal strategy using the indicators of horizontal channel trough-line shifting and longitudinal slope stability, which can be served as a design and management reference for relevant units in the future. The results showed that all kinds of dam removals induced riverbed scours upstream, and depositions and increase stability downstream. The location of maximum scour depth usually occurs at the concave bank and nearby the upstream of dam removal site. The relative horizontal channel trough-line shifting for the removal of the left bank of the dam is smaller than those for the other cases, and the channel slope is milder than those for the other cases. In addition, the location of maximum scour depth is far away from the levee bank when the left bank of the dam is removed. Therefore, this study suggests that the removal of the left bank (top width b/2 and bottom width b/3) of the dam to be an appropriate improvement program. |
本系統中英文摘要資訊取自各篇刊載內容。