Abstract: The failure of bedrock laminar slope mostly happens due to heavy rainfall; and it causes huge losses to people’s lives and property. To explore the process of rainfall infiltration into bedrock laminar slope under heavy rainfall, a new rainfall infiltration model for this slope is built and then a formula of calculating infiltration rate and wetting front depth about slope is obtained for different stages based on Green-Ampt infiltration model. The geometric characteristics of slope and the seepage of saturation zone are considered in this new model. Based on the rainfall infiltration model and limit equilibrium method, an analytical expression of safety factor is developed for bedrock laminar slope under different rainfall durations by considering the seepage of saturation zone. The expression is used to analyze the variation of the surface of bedrock and the surface of wetting front. It is shown that the calculated results have a high consistency with that of slope model test. Moreover, the proposed procedure and the traditional method are employed to analyze the process of rainfall infiltration and the regularity of stability of Zhangjiawan landslide under the rainfall intensity of 30 mm/h. The variations of wetting front depth and safety factors with the increase of rainfall duration are obtained. The results show that, the proposed procedure is superior to traditional method in analyzing the stability of bedrock laminar slope.

Key words: heavy rainfall, laminar slope, rainfall infiltration, wetting front, stability, safety factor