Approximate upper- and lower-bound analyses of translational rainfall-induced landslides in curvilinear hillslopes

Increased frequency of rainfall-induced landslides (RILs) with global climate change is expected to be a huge challenge. Previous studies have focused on RILs encompassing the examination of rotational failure mechanisms and straightforward slope geometries, notably those pertaining to planar or cutting slopes. However, instability issues of curvilinear hillslopes have received less attention, although they are of great significance for early warning landslides in more common natural slopes. This study presents a progressive failure mechanism for curvilinear hillslopes in which the local failure initiates at the steepest zone and gradually extends to upslope/downslope flat regions. By means of upper- and lower-bound analyses, approximate criteria for the onset of a translational landslide with respect to the critical wetting front depth and the failure positions are derived. Unlike traditional theories, upper- and lower-bound analyses are unaffected by slope topology, self-weight of soil and cohesion effects. By conducting a case study at the end of the study, the suggested criteria are found to exhibit notable merits in their straightforward implementation for evaluating the stability of curvilinear natural slopes under varying precipitation patterns.