Numerical simulation on fine fragmentation features of coal during pick cutting under various influencing factors

Coal cutting by shearers is the primary dust source in fully mechanized mining faces. This study explores the fundamental fine fragmentation and dust generation potential evolution mechanism, providing a mathematical basis for fine fragmentation and dust generation potential. To address the analytical model geometric idealizations, a PFC3D discrete element model was developed to quantitatively capture the effects of lateral pressure, dynamic intrusion velocity, and pick cone angle on the core evolution. Synergistic analysis reveals the core spatial distribution is highly stress-sensitive. Under asymmetric loading, the unconfined free surface core area peaks at 0.00639 m2 at a 3 MPa lateral pressure before shifting to macroscopic brittle spalling, whereas the constrained pressurized surface expands monotonically. Higher intrusion velocities exacerbate strain-rate effects, and larger cone angles induce wider stress dispersion, both expanding compacted core volumes and elevating intrusion forces. Based on the mechanical response patterns of a single cutting tooth, this article elucidates the evolutionary mechanism of microscopic coal fragmentation under the influence of multiple factors, providing a crucial theoretical basis for suppressing dust generated by coal cutters at the source and reducing the potential for dust generation.