Failure process analysis of a catastrophic landslide in Zhenxiong triggered by prolonged low-intensity rainfall using centrifuge tests

Rainfall-induced landslides are a prevalent geological hazard worldwide, causing severe ecological and socio-economic impacts. While they can be triggered by extreme rainfall, typhoon storms, and prolonged low-intensity rainfall, the damage caused by landslides from prolonged low-intensity rainfall is often underestimated. However, catastrophic landslides can occur when such rainfall couples with fragile geological conditions and groundwater seepage. In January 2013 and January 2024, two devastating landslides occurred in Zhenxiong County, each causing over 40 fatalities. Both events occurred during Zhenxiong's unique prolonged rainy (snowy) season, drawing significant attention from researchers. We conducted a centrifuge test to simulate the failure process of the Zhaojiagou landslide in 2013 under the influence of prolonged low-intensity rainfall and groundwater seepage. Furthermore, the high mobility genesis and post-disaster deformation evolution of the disaster were analyzed based on ring shear tests and remote sensing interpretation. Our work reveals the destabilization behavior and failure characteristics of catastrophic landslides induced by prolonged low-intensity rainfall. It also offers insights into the coupling effect of geology, rainfall, and groundwater on small-scale landslides that turn into major disasters.