A Simplified Analytical Method to Predict Shallow Landslides Induced by Rainfall in Unsaturated Soils

In order to assess slope stability owing to rainfall, the availability of an effective and simple‐to‐use methodology, relating directly rain to eventual landslide triggering, is undoubtedly useful. To this purpose, a simplified method aimed to the prediction of rainfall‐induced shallow landslides in unsaturated soils is proposed in the present study. This method takes advantage of some closed‐form solutions to evaluate the change in pore pressure due to infiltration of a rainfall characterized by a given intensity and duration, and the simple scheme of infinite slope to calculate a threshold for the change in pore pressure when the slope is under limit conditions. Particularly, using the present approach, a critical curve can be defined to establish the rainfall events that can trigger a failure process at a given depth, where suction before rainfall is known. The proposed method appears promising from an engineering viewpoint, since it is simple to use and requires few parameters as input data. In addition, these parameters can be determined from conventional geotechnical tests. The validity of the proposed approach is corroborated by some comparisons with the results of well‐documented case studies.