本研究在實驗室進行堰塞壩溢頂破壞而形成圓頂堰之渠道實驗，以高 速攝影機進行影像分析，並探討堰塞壩受上游入流水的影響、堆積體內部之滲流作用、洪峰流量、輸砂量、水流功率及圓頂堰之特性。本研究參考既有時域反射方法(Time Domain Reflectometry, TDR) 於沉陷量測和橋墩沖刷之初步建議，以監測各個時間點之潰壩行為，不僅可以達成壩體內部之監測，自動化監測可去除人為誤差的影響。本研究探討圓頂堰公式所預測之各時段之出流量。在潰壩歷程中，出流量與輸砂量皆呈現出單峰曲線歷程，但公式所求得之洪峰流量與本實驗中使用之連續方程式所得到之結果比較後發現有低估情形。本研究建議若堰塞壩材料與本實驗相同，則出流量之峰值可由本文提出之關係式以入流量估算。在真實情況中，若已知降雨量，以集水區公式推算入流量，便可推估潰決後最大之出流量，以達到監測和預防效果。;The overtopping process of an embankment dam was conducted in an experimental flume in this study. A high-speed camera was used to analyse images in order to understand the relationships among the upstream water level, seepage, sediment discharge, inflow, outflow and dome characteristics. This study takes into account the time domain reflectometry (TDR) for subsidence easurement, which is capable of monitoring the dam failure process at various time stages. By employing TDR, it not only achieves the purpose of stratified monitoring, but it can also reduce the chances of human errors. The overtopping outflow for each time period is obtained by using the circular-crested weir formula. During the dam break process, the outflow and sediment discharge are represented as single-peak curves, which show a monotonic decreasing trend after the peak. The experimental results are slightly lower than the circular-crested weir formula. An empirical formula for the overtopping peak discharge is proposed, which is useful for warning and monitoring purposes for landslide dams and levee overtopping.
