Abstract: Common geological disasters such as landslides, mudslides, rock slides, etc. usually involve the movement of particles of different shapes, and most of these particles have different sizes and contents. Based on a typical particle column collapse test, the parameters required for the discrete element simulation were first determined according to the test method, and then the random polyhedron method was used to generate large particles with a controllable slenderness ratio. After that, the discrete element method was used to determine the contents of different large particles. The effect of morphological changes on the collapse characteristics of the binary particle column was then studied. The results of the study showed that: (1) The discrete element method could better reproduce the collapse process of the binary particle system composed of small spheres and polyhedrons in laboratory experiments; (2) In a binary particle column system composed of irregular large particles and small balls with different slenderness ratios, when the content of large particles was higher than the critical content of 20%, the duration of the collapse of the binary particle column varied with the non-spherical large particles; (3) In a binary particle column composed of irregular large particles and small balls with different slenderness ratios, when the content of large particles was higher than the critical content value of 20%, under the same percentage of large particle content, the increase of the slenderness ratio of the large particles increased the average coordination number of the large particles and reduced the movement ability of the particles. A stronger interlocking effect was formed between the large particles, which reduced the overall fluidity of the particle column and made the column finally pile up to a higher height, a shorter maximum distance and a smaller normalized kinetic energy peak; (4) In the binary particle column composed of irregular large particles and small balls with different slenderness ratios, small particles could significantly reduce the friction and interlocking effect between large particles, increase fluidity, and reduce the impact of large aggregate shape on the collapse process.

Key words: binary particle column, collapse process, slenderness ratio, discrete element method