Fig. 1. Experimental system

Fig. 2. Schematic diagram of image averaging method

Fig. 3. Image distortion correction

Fig. 4. Particle recognition algorithm

Fig. 5. Voronoi diagram of surface particles on the side of the drum

Fig. 6. Distribution of the area and number of edges of the Voronoi polygon on the side of the drum

Fig. 7. Distribution of the number of particles involved in a single rearrangement

Fig. 8. Three basic particle clusters

Fig. 9. Basic cluster division for large-scale particle rearrangement

Fig. 10. Distribution of linear cluster directional angle

Fig. 11. Difference result of two adjacent frames of images during the avalanche process

Fig. 12. Estimation of avalanche area

Fig. 13. Correlation analysis between changes in passive layer particle stacking structure and avalanche