LI Yu-peng;GUO Li-an;HU Pan;HAO Bing-yuan;WANG Chen-long;ZHAO Ting-ting;ZHANG Tao;Shanxi Pingshu Coal Industry Co.,Ltd.;Taiyuan University of Technology;Shanxi Jichangtai Mine Engineering Technology Co.,Ltd.;During roof presplitting blasting for auxiliary air inlet and roof cutting gob-side entry retaining at Pingshu Coal Industry's 8213 working face,blast-induced fractures exhibit random propagation patterns and deviate from presplitting holes alignment due to the influence of pre-existing fractures. The presplit fractures exhibit discontinuous,rough,and serrated morphologies,resulting in rock masses interlocking that hinder effective separation along the presplitting hole plane and delay pressure relief. Consequently,the surrounding rock of the gob-side entry retaining maintains prolonged high-stress conditions,leading to significant deformations. To enhance roof-cutting effectiveness in fractured rock masses through presplitting blasting,this study employs the discrete element particle expansion method to numerically investigate how characteristic parameters of fracture distribution influence presplit fracturing outcomes. Furthermore,a multi-parameter coupling simulation system for rock mass presplitting blasting and a quantitative evaluation methodology for blast effect were established. Meanwhile,an optimized control strategy was proposed that leverages the synergistic effects of grouting reinforcement,segmented stemming,and decked charge configurations. Field validation tests confirmed the feasibility of this synergistic approach. Key findings reveal three dominant factors governing presplit blasting effectiveness:( 1) the intersection angle( β) between natural fractures and the blast hole alignment,( 2) fracture length( L_f),and( 3) fracture spacing( d). As β increases from 0° to 90°,the primary fractures' role transitions progressively from assisting to inhibiting the fracturing process. In contrast,the presplit fractures evolve morphologically from smooth,continuous linear/gentle-zigzag patterns to irregular,rough,and discontinuous X-shaped configurations. The influence of L_fintensifies with the increasing intersection angle( β),while the smoothness and continuity of presplit fractures degrade substantially. The detrimental effect of primary fractures diminishes with greater fracture spacing( d). By implementing grouting reinforcement combined with segmented plugging stemming and spaced charging,both rock mass homogeneity and uniformity of explosive energy distribution in presplitting holes are markedly enhanced,ultimately generating distinct presplit fractures along the full blast hole length at a 70% fracture rate.
2026 01 v.43;No.179 [Abstract][OnlineView][Download 1756K]