Abstract: This paper first briefly introduces the principles of seepage in the unsaturated soils. Then, a case history is presented to analyze the effect of the precipitation on the stability of the slopes. The distribution of the pore pressures along the slopes is numerical simulated. A new slope stability analysis approach is presented by introducing the matric suction into the stability analysis.

Key words: Unsaturated Soils, Precipitations, Matric Suction, Slope Stability