臺灣博碩士論文加值系統

水平束縮沖刷是水流在河道中橋台外所造成的河床沖刷行為。本研究利用試驗水槽進行束縮沖刷實驗，將試驗結果與前人公式之推估作比較，找出適當之迴歸式。並探討影響束縮刷深的主要因素，以了解造成底床嚴重刷深之機制，並探討改善束縮沖刷的工法。
就清水沖刷而言，束縮沖刷深度受兩因子影響；一為束縮率，一為平衡水深。當束縮率增加時，束縮刷深所在總刷深的比例會比較多。反之，則局部刷深則佔總刷深的比例較高。不過當沖刷形式為局部沖刷時，束縮率是有限制的影響沖刷深度。

The horizontal contraction scour around the bridge abutment is examined in this study by experimental study. Both short and long contractions are performed in the laboratory, and are compared with available formulae. Experimental results of the contraction scour are helpful to understand the mechanism of bed variation, and to improve the scour countermeasures.
The depth of the contraction scour is controlled by two factors, i.e. the contraction ratio and the equilibrium water depth. Increasing the contraction ratio, contraction scour will take high proportion of the total scour depth. On the contrary, the local scour depth will take a large proportion of the total scour depth. Since is mainly due to the local scour, the contraction ratio only affected the depth of the scour slightly.

中文摘要I
ABSTRACTII
目錄III
圖目錄VI
表目錄VIII
照片目錄VIII
符號表X
第一章 前言1
1.1 研究動機與目的1
1.2 研究方法2
1.3 本文架構3
第二章 文獻回顧4
2.1 長矩形束縮沖刷4
2.2 橋台之局部沖刷6
2.3 束縮沖刷與局部沖刷之關係8
2.4 估計水平束縮刷深之公式8
2.5 現有公式評估12
第三章 理論分析及實驗設備與規劃14
3.1 沖刷機制之探討14
3.2 沖刷平衡公式15
3.3 清水沖刷之平衡理論19
3.4 因次分析19
3.5 試驗設備與儀器22
3.6 試驗條件22
3.7 試驗步驟23
3.8實驗規劃23
3.8.1 實驗模型尺寸之確定23
3.8.2 馬達流量之率定23
第四章 實驗結果與討論24
4.1 束縮沖刷試驗結果24
4.2 局部沖刷與束縮沖刷24
4.2.1 局部與束縮刷坑之關連24
4.2.2 束縮刷深之定義25
4.2.3 束縮沖刷坑流況之探討25
4.2.4 局部沖刷坑之探討26
4.2.5 局部沖刷坑之幾何相似27
4.2.6 局部沖刷與束縮沖刷之分界27
4.3 濁水沖刷28
4.4 沖刷深度的影響因子28
4.4.1 水深與上游福祿數28
4.4.2 束縮比及橋台長度29
4.4.3 剪力比值與束縮率與底床質粒徑29
4.4.4 短縮刷深與理論公式之比較29
4.4.5 束縮刷深與理論公式之比較30
4.5 試驗現象30
第五章 結論與建議34
5.1 結論34
5.2 建議35
參考文獻36
附表38
附圖47
附照片78
本文架構流程圖89

張學齡，[橋涵水文]，人民交通出版社，北京，(1995)。曾明性，[影響渠道窄縮段底床沖刷因素之探討]，碩士論文，國立臺灣大學土木工程研究所，台北，(1990)。Ashida, Kazuo, “Study on the stable Channel through Contraction,” Annual Report of Disaster prevention Research Institute, Kyoto Univ., Kyoto, Japan, July,pp. 312-327(in Japanese) , (1963)Ballio F., ”local and contraction scour at bridge abutment”, politecnico di Milano, dept. I.I.A.R.(hydraulics and environment),20113 Milano italy (1999) Gill M.A. ”Bed Erosion in Rectangular long Contraction”, ASCE Journal of Hydraulics Division , vol.107, n. HY3. 273-284(1981)Hoffmans, G.J.C.M., H.J. Verheij (1997), scour manual, Cap 2,AA.Balkema, Rotterdam. Laursen E.M., ”Scour at Bridge Crossings”, ASCE Transactions, Vol.127, Part I, 166-180(1962)Laursen E.M., ”An Analysis of Relief Bridge Scour”, ASCE Journal of Hydraulics Division, vol.89, n. HY3. 93-118(1963)Komura S., ”Equilibrium Depth of Scour in Long Contractions”, ASCE Journal of Hydraulic Division, Vol. 92, n. HY5, 17-37(1966)Lim S.Y., ”Clear Water Scour in Long Contractions”, Proceeding Institution of Civil Engineering-Water, Maritime & Energy, Vol. 101, 93-98. (1993)Melville B.W., ”Local Scour at Bridge Abutments”, Journal of hydraulic engineering, vol.118, No.4, (1992)Richardson E.V., Davis S.R. (1995),”Evaluating Scour at Bridges, 3rd Edition”, HEC-18, Federal Highway Administration, U.S. Department of Transportation, Washington, D.CUmbrell E.R., Young G.K., Stein S.M., Jones, J.S.(1998),”Clear-Water Contraction Scour under Bridges in pressure Flow”,Journal of Hydraulic Engineering, Vol. 124, n. 2,236-240.Webby M.G., ”General Scour at a Contraction”, Bridge Design and Research Seminar, National Roads Boards, N.A.RRU Bulletin 73, 109-118(1984)