Abstract: The clayey gravel layer of the Anqing Formation is a special geological body composed of gravelly pebbles and clay. Its cementation force will be greatly reduced by the influence of rainfall, causing slope instability and damaging surrounding farmland and public facilities. Therefore, in this paper, the slope rainfall erosion experiment was carried out at the site to study the failure pattern and instability mechanism of slopes with different slope angles in the process of rainfall. The results show that the formation of slope ditches in the process of rain erosion of clayey gravel layer is roughly divided into the following three stages: surface erosion stage, fine trench formation stage and gullage network formation stage. At the same time, the larger the slope of the slope, the more conducive it is to the formation and widening of the slope ditch, which is not conducive to the stability of the slope. At the same time, whether the gravel on the slope of clayey gravel rolls down depends mainly on the slope ratio. The research results can provide a reference for the protection and treatment of local slopes. 

Key words: Clayey Gravel Layer, Scouring Test, Slope Failure Mechanism, Slope Ratio