Abstract: This paper presents a case history results of evaluating the stability of high mountain slopes after the soaking of rainfall waters, and the hazards of localized storm water accumulation induced by the blocking of drainage ditches by tree leaves on the slope stability. A case history of a building near the high mountain slope was numerically analyzed by using commercial finite element analysis software PHASE2. The numerical slope stability model of the soaked soil with rainfall accumulated at the toe of the slope was established by using the strength reduction method. The results indicate that, the controlling factor of the slope stability is governed by the properties of at the interface of the red clay and the highly weathered bedrock. Under the soaking of rainfall water, the stability of the slope reduces significantly, under this condition, the stability of the slope is controlled jointly be the soaking line and the above-mentioned interface. When the soaking line is close to the interface between the red clay and the highly weathered bedrock, the global stability of the mountainous slope reduces significantly, and even causes slope instability.

Key words: high slopes, precipitations, local areas, slope stability, mountain area