Table 3 Model mechanical parameters.

Ball R_min/mm

Parallel bond modulus E*/Gpa

2.0

Ball radius ratio R_min:R_max

Particle stiffness ratio k_n*/k_s*

2.5

Ball stiffness ratio k_n/k_s

Parallel bond tensile strength σ_b/Mpa

32

Ball friction coefficient µ

Parallel bond cohesion c_b/Mpa

24

Clump R_min/mm

Particle friction coefficient µ*

0.2

Clump radius ratio R_min:R_max

Friction angle ƒ/°

32