Effect of Particle Size on Stick‐Slip Dynamics of Shear Bands Considering Randomness of Initial Particle Positions in Discrete Element Modeling

ABSTRACT Stick‐slip dynamics of shear bands is vital to the evolution of geological hazards such as earthquakes and landslides. Extensive studies have been conducted to analyze the effect of the particle geometry on the stick‐slip dynamics. However, the impact of the initial positions of these particles has rarely been studied. With the aid of discrete element method modeling, the influence of particle size on the stick‐slip dynamics is revisited, with particular emphasis on initial particle positions. The initial particle positions in this study are sampled with Monte Carlo simulations. The results illustrate that a shear band with larger particles tends to exhibit fewer stick‐slip events, longer recurrence time, and more evident friction drop. The stick‐slip dynamics is strongly affected by initial particle positions, and the effects increase with the particle size. Parameteric analyses indicate that these effects could only be slightly influenced by the contact models of the particles, model parameters, boundary conditions, and model dimensions. These findings provide new insights into the stick‐slip dynamics and emphasize how the initial particle positions influence the stick‐slip dynamics of faults and earthquakes.