自然土壩破壞的眾多破壞機制之一是滲流侵蝕引起的邊坡破壞。滲流侵蝕使土壤粘結鬆動，導致土壤結構失效。本研究通過實驗室試驗確定了滲流侵蝕引起的臨界地下水位。進行了砂箱實驗以模擬土壩與水的接觸。首先基於土壤的邊坡穩定性，發展破壞的臨界地下水位控制方程。其次以實驗室實驗，測試控制方程式之正確性。控制方程算出地下水的臨界高度為19.117厘米，實驗將地下水高度保持在 16 厘米、18 厘米和 20 厘米。試驗結果發現，大壩在地下水位達 18 厘米時發生潰壩，與方程式推算結果相近。 One of the many failure mechanisms for natural earth dam failure is slope failure due to seepage erosion. Seepage erosion loosens the soil bonding causing failure in soil structure. This research determine the critical groundwater level due to seepage erosion by laboratory experiment. A sandbox experiment is done to recreate the landslide dam's exposure to water. A governing equation has been developed for the critical groundwater level for the failure of the landslide dam. The governing equation is based on the slope stability of the soil. Thereafter, that governing equation has been justified by the laboratory experiment. The experiment was done by varying the height of water near the value found by the governing equation. The governing equation gave the critical height of the groundwater is to be 19.117cm. the experiment was done keeping the heights of groundwater at 16cm, 18cm, and 20cm. The experimental result showed that the dam failed at an 18cm groundwater level. The result found by the experiment satisfies the value from the equation.
