Abstract: Indoor artificial rainfall simulation test was conducted to investigate the mechanism of retrogressive landslide, and the criteria of rainfall warning for the study were proposed. The Maijianwo landslide in Lingbao City of Henan Province was taken as a case study. In the model test, moisture sensors, tracking points and digital cameras were adopted to record variations in the moisture of crucial parts, the surface deformation and crack propagation. Research results showed that the rainstorm led to destruction from the bottom of slope to the top gradually as a retrogressive mode. The slope failure process was divided into three stages as deformation activation, deformation acceleration and integral destruction in accordance with the critical time points by analyzing the deformation characteristics and moisture monitoring data of crucial parts. According to the above failure mode, the cumulative rainfalls E₁ (75mm) and E₂ (180mm) were respectively set as the orange and red warning criteria for the Maijianwo landslide when there were penetrating cracks on the slope toe and shoulder.

Key words: retrogressive landslide, model test, cumulative rainfall, destruction regularity, warning criteria