Downhill progressive landslide hazard assessment: a simple framework for prediction of triggering thresholds and failure modes

Abstract

The pronounced discrepancies in triggering intensities and failure modes observed in downhill progressive landslides pose significant challenges to their risk prediction and mitigation. Instead of focusing on an individual triggering event and/or failure mode as done in previous studies, this study systematically explores the instability issues of downhill progressive failure in long slopes. A unified analytical model is proposed to understand these observed discrepancies, in which criteria for the initiation of slope failure corresponding to all possible failure modes are formulated. Accordingly, a simple framework is established that is capable of predicting possible triggering thresholds and failure modes in advance. This would improve the accuracy of landslide hazard assessment, which is often reduced by the unknowns of the failure mechanisms and inaccurate assumptions of stress distribution along the failure surface. Furthermore, three practical cases are analyzed based on the established framework, and the findings are compared with field observations and existing studies, showing good consistency. This work gives an insight into a systematic understanding of the various failure phenomena in downhill progressive landslides and provides a reference for their risk assessment and subsequent decision-making.