不同間距丁壩群之局部沖刷試驗研究

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，而丁壩佈置後之水理、輸砂與底床沖淤交互機制頗為複雜，值得加以分析其行為。本實驗針對濁水溪常見之手槍型丁壩工法進行探討。 本研究藉由長直渠槽，於清水沖刷條件下進行浸沒式手槍型丁壩群試驗，設計不同間距與不同福祿數之案例，分別觀察手槍型丁壩群之壩頭沖刷深度變化，藉以了解水流沖擊手槍型丁壩群之沖刷機制。 利用實驗數據獲得之迴歸式，當得知福祿數、水深壩高比(h/H)及間距壩長比(D/L)時，即可預估丁壩頭之最大沖刷深度，作為工程實務應用之參據。

Spur dike including permeable, impermeable, submerge and emerge, is currently a common method regarding engineering in our country. After building spur dike, it brings complicated interaction mechanism of water management, sediment, and seabed erosion, which is a worth analyzing process. This experiment focuses on investigating Pistol -shaped Spur dike construction method in Jhuoshuei River. In order to investigate the mechanism of water impact on Gun-shaped Spur dikes, this study concentrates on submerged Gun-shaped Spur dikes test, using long straight flume experiment in clear-water scour condition, and designing different spacing and random Froude number case to observe scour depth change on Gun-shaped Spur dikes. We can use Froude number, water depth of the dam height ratio (h/H) and spacing ratio (D/L), obtaining from the regression equation in the experiment data, to estimate the maximum scour depth as the basis for the practical application of engineering reference.