Antecedent rainfall induced shallow landslide: A case study of Yunnan landslide, China

We present a case study of antecedent rainfall induced failure of engineering slope. The impacts of pore-water pressure, pore-water pressure increment, water content, and the factor of safety are investigated by numerical models for an actual slope in Yunnan, China. The results indicate that antecedent rainfall plays an important role in the stability of the slope. The model reasonably explains the time lag between the occurrences of rainfall and landslides. Pore-water pressures signicantly change at the upper layer of redclay slope; the occurrence of cracks at the top of the slope agrees with the field observations before landslide. The saturated zone of the slope gradually expands from the top to bottom of the slope; the major reason for landslide is that the surface stagnant water, after rainfall, gradually inltrates into the weathered gneiss rock, resulting in decrease in the strength of weathered gneiss rock. Then, the weight of the later rainfall leads to landslide of the slope. The factor of safety of the slope is evaluated by the modied limit equilibrium methods. It is shown that the actual failure occurs when the calculated factor of safety approaches its minimum, i.e., 0.97. The landslide is characterized by shallow landslides.