Abstract:
Rockburst prevention is critical for the safe and efficient extraction of coal resources. Current assessments of impact tendency mainly rely on macroscopic experimental tests. However, the complex meso-structure of coal fundamentally governs its macroscopic behavior, making it difficult for existing experimental methods to reveal how meso-structure influences impact tendency. To address this gap, this paper employs the discrete element method(DEM) to systematically investigate the influence of mesoscopic parameters on the impact tendency of coal, aiming to establish a quantitative relationship between mesoscopic characteristics and macroscopic mechanical responses, thereby providing a theoretical basis for rockburst control. The study focuses on three key factors——particle friction coefficient, bond strength, and micro-fissure distribution——and analyzes their effects on impact tendency indicators, while also examining the discrepancies among different indicators under identical conditions. The main findings are as follows: ① the friction coefficient plays a significant role in regulating the impact tendency of coal. As the friction coefficient increases from 0.20 to 0.50, the uniaxial compressive strength(UCS) increases from 20.9 MPa to 23.6 MPa, while the dynamic failure time decreases from 101.6 ms to 34.6 ms. Under low friction coefficient conditions, inter-particle deformation becomes more coordinated, and damage develops more thoroughly, leading to deviations between different impact tendency indicators. ② Bonding strength shows a positive correlation with impact tendency indicators. When bonding strength increases from 5 MPa to 30 MPa, UCS increases by 545%, dynamic failure time decreases by 91.4%, and the failure mode transitions from progressive multi-crack propagation to brittle-dominated fracturing, with more concentrated energy release. ③ For both single- and double-fissure specimens, the weakest impact tendency is observed at a fissure inclination of 30°. Compared to single-fissure specimens, double-fissure specimens exhibit more pronounced degradation in mechanical parameters. Furthermore, results across different fissure distribution angles indicate that the orientation of fissures relative to the loading direction not only weakens coal strength but also significantly affects fissure propagation, thereby influencing impact tendency indicators. Based on these findings, this paper suggests that engineering measures for rockburst prevention should focus on three strategies: reducing the friction coefficient, softening the bonding strength, and inducing complex fissure networks.