Multi-factor contributions to blast-induced rock fragmentation behavior

Blast-induced rock fragmentation is governed by multiple factors, yet their relative contributions remain unclear. In this study, five sandstones with markedly different physical and mechanical properties were selected. A multi-dimensional dataset comprising 43 features was constructed through mineralogical identification, static and dynamic mechanical testing, and laboratory blasting. Pearson correlation and SHAP analysis were employed to systematically evaluate the influence of each factor on mean fragment size obtained in laboratory-scale single-hole blasting tests. The results indicate that blasting parameters dominate fragmentation, followed by physical–mechanical properties, and then microscopic mineral characteristics. Charge density, charge mass, and charge structure rank as the top three influencing factors. High charge density and effective stemming significantly reduce fragment size. Dense, high-strength rocks tend to produce larger fragments, whereas high-porosity rocks, when combined with high charge density and effective stemming, enable efficient utilization of blast energy. Mineral composition and grain size show limited influence, with SHAP values generally below 0.5. In engineering practice, charge density and charge structure should be prioritized as key control measures, supplemented by rapidly measurable indicators such as wave velocity and density to assess rock blastability. Blasting schemes should be tailored to lithological variations to achieve efficient and cost-effective fragmentation.