Experimental study on the effect of rainfall patterns on the failure mode of debris flows after earthquakes: A case study of Tiantanggou, Jiuzhai

Abstract

Variable rainfall intensity can influence soil permeability and saturation processes, change the mechanical properties of soil, and affect the initiation mode and damage scale of debris flows. To explore the response mechanism of debris flows under different rainfall modes after earthquakes, laboratory tests of artificial rainfall-induced debris flows was performed through a small-scale model trough and rainfall simulation system. Based on the starting process of debris flow under different rainfall patterns, the variation of water content and pore water pressure in the slope was studied. The results show that the landslide transforms to a debris flow under the increasing rainfall model, and the damage scale of the accumulation is the largest; the debris flow under the decreasing rainfall occurs after the backward breaking instability; the initiation of debris flow under uniform rainfall mode results from traceable erosion; local landslides are transformed into debris flows under the middle-peak rainfall pattern; under the Ⅴ-shaped rainfall pattern, the slope erosion is intensified and transformed into debris flow, with the smallest damage scale.The research results can provide reference for the forecast and warning of debris flow in Jiuzhaigou area.

Keywords

• rainfall pattern
• debris flow
• physical model experimentation
• water content