The fatigue weakening of creeping landslides by multi-stage rainfall

Large-scale landslides are widespread and undergo a long-term process of damage accumulation under multi-stage rainfall. Landslides may cause catastrophic damage months or years later, threatening human lives and property. In this study, we focus on the fatigue weakening process of landslides by multi-stage rainfall. We design innovative rainfall-step creep experiments for the shear zone materials of large-scale creep landslides to study the correlation between multi-stage rainfall and landslide deformation. The experimental results show that each rainfall will cause a rapid increase in pore water pressure, which subsequently triggers a short-term acceleration in the deformation of the shear zone material, followed by a transition into a steady-state creep phase. With the increase in rainfall, the number of rainfalls required to trigger failure decreases, the secondary creep time is significantly shortened, and the landslide enters the tertiary creep faster. Under the same rainfall conditions, the lower the stress, the significantly longer the secondary creep time, but the failure occurs earlier, showing a high sensitivity of the shear zone material to rainfall. The rainfall-step creep experiments quantitatively demonstrate the on-site behavior of landslides, showing a cumulative destructive effect of multi-stage rainfall on landslides. Our results exhibit insights for a better understanding of the large-scale landslide from creep to failure.