不同壩高水深比對丁壩群沖刷深度之影響研究

Abstract

丁壩工法為目前國內治理規劃常見之工程手段，類型繁多包括透水與不透水、浸沒與非浸沒等，而丁壩布置後之水理、輸砂與底床沖淤交互機制頗為複雜，值得加以分析其行為。前人大部分都擇一進行浸沒或非浸沒式丁壩，鮮少去比較其沖刷分佈之差異性；因此，本研究探討不同壩高水深比對丁壩群沖刷深度之影響。 本試驗藉由長直渠槽，於非均勻粒徑條件下進行丁壩群試驗，設計不同壩高水深比之案例，分別觀察丁壩群之沖刷深度變化，藉以了解水流衝擊丁壩群之沖刷機制。 利用實驗數據分析得出在未浸沒、洽浸沒、完全浸沒條件下，丁壩群之沖刷坑範圍差異、丁壩壩間沖淤體積變化及丁壩群壩頭沖刷深度遞減率，以便於工程實務上丁壩之設計。

Spur dike, including permeable or impermeable, and submerged or emerged, is currently a common method of river engineering in our country. It is worthy to analyze the complicated interactions among flow, sediment transport, and bed erosion deposition after building spur dike. Most of previous alternative to submerged or emerged spur dike, rarely compared to the erosion of distribution difference; therefore, this study was to investigate depth dike height ratios the effects of spur dike scour depth. In order to investigate the mechanism of water impact on spur dike group, this study using long straight flume under non-uniform grain size condition, and designing case with different depth-dike height ratios to measure scour depth change in front of the dike. Using experimental data can be obtained the spur dike scour range differences, groyne scour volumes between change and decline rate of spur dikes scour depth under emerged, exactly submerged, submerged condition, so that the engineering design of spur dike on the practice.