Preliminary analysis on rainfall thresholds for early warning of the rainfall induced landslides based on “step” deformation characteristics

Since the occurrence of landslide disasters is random and complex, which often causes serious economic losses to people's lives and even threatens life safety, establishing landslide early warning criteria and models is an important means to reduce losses. In this paper, the effective rainfall-deformation rate-improved tangent angle is determined as the key criterion for the early warning of rainfall-type step landslide. Then, the slope single-variable point method is applied to determine the “damage inflection point” and “stability inflection point” on the landslide “step” deformation curve to extract detailed information of the deformation acceleration interval, so as to solve the effective The threshold value of rainfall-deformation rate-improved tangent angle integrated warning criterion. Finally, a 4-stage progressive integrated warning model was established by combining the macroscopic deformation characteristics of the landslide at each stage of development and the spatial and temporal evolution laws. The results show that the transport form of landslide No. 1 in Machi Village is traction type, and the cumulative displacement curve shows typical “step” deformation characteristics under the excitation of rainfall factors. The deformation of landslide No. 1 in Machi village is affected by the early rainfall, and the time interval threshold between the early rainfall and the current rainfall is 10 d, and the corresponding rainfall thresholds in the “early + current rainfall” mode are 24 mm and 32 mm respectively. The study can provide theoretical basis and technical guidance for early warning of this type of landslide hazard.