水位下降时产生的非稳定渗流不利于堤坝边坡稳定，是一个与水力学和土力学有关的复杂问题。开展了非稳定渗流作用下的边坡稳定模型试验，研究了不同土力学条件和水力学条件下，渗流对边坡稳定性的影响，探讨了水位降落指标k/μv与边坡稳定性之间的关系。结果表明：在边坡稳定性分析中，渗流方向是边坡稳定分析的关键，水位降落时渗流向上游方向，边坡安全系数远低于其他渗流方向。边坡失稳发生在水位降落过程中临水坡的渗透力或渗透坡降达到最大的时刻。不考虑渗流方向的计算结果不能正确反映边坡的稳定性，建议边坡稳定分析须正确考虑渗流作用。

The soil slope stability under unsteady seepage is a complex issue related to both hydraulics and soil mechanics. The unsteady seepage caused by water level drawdown goes against the slope stability of dams and embankments. This paper has carried out model experiment on slope stability under unsteady seepage, studied influence on slope stability caused by seepage flow under different conditions both hydraulics and soil mechanics, and discussed the relationship between water drawdown index k/μv and the slope stability. The results shows： The seepage direction is the key factor. The direction of the seepage flow points to the upstream, the safety factor is smaller in this direction than other directions. The slope failure occurs when the seepage gradient reaches the peak. The result which is not considered seepage direction can not correctly reflect the stability of slopes. The slope stability analysis which needs to be combined with seepage is proposed.