明渠匯流隔離牆之研究

Abstract

一般造成渠道排水不良之因素包含渠道狹窄、護岸高度不足或銜接角度不良等，部分問題可由清淤或設置抽水站解決，然而銜接角度不良者須徵收土地進行改道或可於渠道中設置隔離牆，本研究將探討匯流明渠隔離牆之規劃。 計算隔離牆位置先由二維勢能流假設，以施瓦茲─克里斯托夫轉換理論解得分隔流體之自然流線而設計，藉此發揮導流作用，將明渠匯流點延長至下游直線段，避免河水直接相互干擾或甚至使任一側水流受阻。然理論隔離牆位置尚須經過模擬測試，本研究分別以二維勢流邊界元素法以及深度平均之淺水流模式計算模擬隔離牆與流場作用關係，另研究邊界元素法之退化邊界問題。 現實情況中，匯流明渠隔離牆於中港大排與貴子坑溪交會處已有設置，本研究將取其作為研究案例，模擬分析理論隔離牆於真實渠道中受力情形，並與既有隔離牆比較，統整研究結果，探討隔離牆最佳規劃方案並針對原隔離牆提出改善辦法。最後透過多孔介質材料特性建造具舒緩壓力作用之隔離牆，成果良好，希冀對日後河川治理工程有所幫助。

The cause of open channel flooding includes contraction, insufficient height of embankment, inappropriate merged angle, etc. Among the above circumstance, some of the problems can be solved by cleanout or pumping, but the most complicated problem is inappropriate merged angle, it will face land expropriation for river changing. Another choice is to construct a dividing wall in the channel which is the main issue of the research. The design of dividing wall for merged flow can extend the intersection point to downstream, relative uniform flow, avoiding disturbing each side water. Planning dividing wall can follow the steps below: First, use Schwarz-Christoffel transformation to find analytical solution of dividing wall position. Second, calculate the pressure of dividing wall by BEM of 2D potential problems and solve degenerate boundary problems. Or, simulate the action between fluid and wall by depth-averaged sallow water model. For the purpose of combining the research with practice, the research will discuss the case of confluence between Zhonggang chnnel and Quizikeng river. As a sequence describe before, the optimal dividing wall can be found. Furthermore, the study successfully propose a way to improve present dividing wall by using porous material, having the property of dissipating pressure.