A Study on the Energy Dissipation of Stone Revetment and Concrete Block on the Downstream of the Flood Detention Dam

滯洪壩水舌呈豎一字形, 勢必對下游河床產生沖刷與破壞. 一般即於 壩下游舖設水泥護坦或元鼎塊以達消能效果, 但隨著環境及生態的觀念高 漲, 傳統之施工方式己漸漸受到社會大眾的垢病. 本試驗於滯洪壩下 游以堆石護岸及水泥塊代替元鼎塊及水泥護坦, 探討於不同渠床坡度, 流 量及矩形開口寬度, 於壩未游滿之情況下, 堆石護岸及水泥塊對消能效果 及下游沖刷深度之影響. 經試驗得知, 消能效果隨流量, 坡度增加而 增加, 而隨矩形開口寬度之增加而減小.就堆石護岸及水泥塊排列方式而 言, 在本試驗之範圍下堆石護岸長度愈長下游沖刷坑較淺; 堆石護岸寬度 愈寬則下游沖刷坑較深. 本試驗以生態環境為考量, 並與前人之試驗 研究比較, 得到一較佳之結果, 壩下游舖設堆石護岸及水泥塊確實可以安 定河床; 故此設計可供日後河川治理一較好之選擇.The flow from the rectangular opening of the flood detention dam will produce scouring and damage on the downstream riverbed. Generally, the way to reach theeffectiveness of energy dissipation is building concrete apron or Hexa-HollowTri-Leg Structure. Now, the environmental and ecological considerations are toattach much importance. Traditional apron structure are not accepted by people. On the downstream of the dam, the stone revetment and the concrete block gaveplace to the concrete apron and the Hexa-Hollow Tri-Leg Structure. This studydiscusses the effectiveness of energy dissipation and the downstream scouring hollow deep under different slopes, discharges and widths of the rectangularopening in the case of having not deposited yet on the upstream of the dam. In this research, we find that the effectiveness of energy dissipation ofapron will increase with the increasing of slop and discharge, but will decreasewith the increasing of width of the rectangular opening. According to the type of the stone revetment being arranged, the longer the length of stone revetmentis and the shallower the downstream scouring hollow deep is. The width of stonerevetment is and the deeper the downstream scouring hollow deep is. We studied the study ecologically and the result in comparison with other study. We find that the stone revetment and the concrete block being arrangedbeside the downstream the dam has its efficiency on steadying riverbed. Whenapplying to the river treatment, it must be a good choice