Abstract：Based on actual survey data，the results of indoor physico-mechanical test and engineering practice，the relationship among safety factor of slope，shear strength index and saturation-area ratio of slope-mass under intensive rainfall was researched；furthermore，their mathematic statistics related expression was established. According to this related expression，difficulty in analyzing stability of shallow slope under intensive rainfall by the strength reduction limiting equilibrium method of non-separation contact elastoplastic finite element was discussed. The results are shown as follows. First，with making full use of the mathematic statistics related expression established and selecting different saturation-area ratios of slope-mass，corresponding equivalent shear strength index of slide plane under intensive rainfall is obtained，which acts as the one of contact elements on slide plane in the strength reduction arithmetic of non-separation contact elastoplastic FEM. Second，the stability of shallow slope under intensive rainfall may be more accurately analyzed by the above method，which may more clearly reflect actual state of slope disintegration，deformation and failure. Third，the results may afford more reliable and adequate bases on calculation of the safety factor and analysis of slope stability；meanwhile，according to different saturation-area ratios of slope-mass，more accurate forecast of this type of shallow landslide may be carried out more conveniently by the above method. Fourth，the mechanism of disintegration，deformation and failure of shallow landslide under intensive rainfall is revealed. Furthermore，it is confirmed that intensive rainfall is the most decisive triggering factor that leads to sudden instability of shallow landslide.
