投潭水沖擊位置受制上下游渠床坡度影響之探討

The Effect of Free Over-fall by Upstream and Downstream Channel Bed Slopes on Impact Position

10.29417/JCSWC.201512_46(4).0005

黃劼暉(Jie-Hui Huang)；謝俊賢(Chun-Hsien Hsieh)；陳正炎(Jen-Yan Chen)

沖擊位置 ； 渠床坡度 ； 投潭水 ； Impact position ； channel bed slopes ； free over-fall

中華水土保持學報

46卷4期（2015 / 12 / 01）

233 - 238

繁體中文

台灣河道大多坡陡流急，縱向沖刷能力大，為達消減洪水沖刷能力，達到穩定河床，保護跨河、防洪構造物安全及取水供民生、灌溉之目的，設置跌流工、防砂壩或攔河堰等橫向構造物為慣常使用之方法。雖可穩定上游河道，卻因砂石無法向下運送，而淤積於跌水工前河道渠床，導致跌水工上游渠床產生坡度，使水流成超臨界流況沖擊下游渠床，亦是消能工最易受損之處。本研究主要係藉由理論推導與實驗比較，探討投潭水沖擊位置受制跌流工上下游坡度改變之影響。

Most Taiwanese rivers are rapid and steep, with a large capacity for vertical erosion. Hydraulic structures that cross rivers, such as drop structures, check dams and weirs, are widely used to decrease flood erosion, to stabilize riverbeds, to protect structures that cross rivers and to provide public water and irrigation. The hydraulic structures make the upstream channel stable and sediments cannot be transported downstream so they remain in front of the riverbed of drop structures on the other side. These structures usually induce a change in the upstream slope and the super critical flow condition, which produces a large impact force downstream and destroys energy dissipating structures. This paper studies the impact location for different upstream and downstream channel bed slopes and compares a theoretical analysis and experimental results.