A determination method of rainfall type based on rainfall-induced slope instability

This work presents a determination method of rainfall types based on rainfall-induced slope instability to provide an effective approach for early warning of different patterns of rainfall-induced slope failures/landslides. Firstly, 5808 scenarios of slope instability are simulated with 11 kinds of soil properties under 528 designed intensity-duration (I−D) conditions to get the threshold curves of slope failure under different rainfall conditions and soil properties. Then through analysis of the threshold curves when slope failure occurred, rainfall is classified into two types: short-duration—high-intensity (SH) type and long-duration—low-intensity (LL) type. According to the analysis results, it indicates that rainfall types affect the initiation of slope failure, i.e., different I−D conditions will affect the slope failure initiation under LL type rainfall, while the slope failure initiation will not be affected by the change of I−D conditions under SH type rainfall. In addition, the results show that the classification of rainfall types does not depend on the soil shear strength parameters (effective cohesion and effective internal friction angle), although the change of soil shear strength parameters will cause the shift of threshold curve of slope failure in the I−D conditions two-dimensional (2D) plane. The findings in this study benefit to understanding the effect of rainfall type on the mechanism of slope failure initiation, which will promote the development of an early warning system of slope failure in the future by considering the identification of rainfall types.