本研究藉由渠槽實驗模擬土石壩於小流量下之滲流破壞過程。實驗之壩體由非凝聚性且粒徑均勻之越南矽砂組成，因此本身滲透性高，壩體內滲流面逐漸升高，當滲流至壩體下游邊坡處，從壩趾處開始發生破壞，而滲流造成溯源沖刷，破壞面漸次往壩體上游面發展直至壩體整個潰流。 本實驗分為二部份：第一部份為壩體未破壞時，壩體內部滲流特性之探討；第二部份為壩體發生破壞時，壩體崩塌速率及崩塌土體流動機制之探討。以實驗資料可得無因次式 ，並以此無因次式來預測非凝聚性土石壩崩潰長度與時間之關係，對斜坡土體滲流破壞引致土石流之預警及疏散有相當之功效。 The study simulates the process that dam crashed by seepage under small discharge. The composition of dam is non-cohesive and uniform, so that it has high permeability. When the seepage surface arises until seepage reaching the downstream end of dam, the initial failure occurs from the toe. Simultaneously seepage causes headcutting, the gradually develops toward upstream until dam collapsing. The experiments have two parts: the first is discussing the characteristic of seepage before the dam crash; the second is discussing the rate of collapse and the characteristic of fluid soil, when the dam is collapsing. According to the experiment data we can find the dimensionless equation to forecasting the relation between the collaped length and elapsed time, the result is very useful for prevention and evacuating the debris flow induced by the seepage failure of the dam.
