Hybrid FEM-DEM and AHP-entropy framework for blasting parameter optimization: A case study of hard rock metal mine in China

• A coupled FEM-DEM numerical simulation model is established to systematically investigate the effects of multi blasting parameters on blasting outcomes, providing a reliable numerical analysis basis for parameter optimization. • A multi-index comprehensive evaluation model integrating the AHP-entropy method, which effectively combines subjective expert experience and objective data characteristics, enhancing the scientific rigor of blasting effect evaluation. • Field tests validate that the theoretical evaluation findings and numerical results are in good agreement with field observational data, confirming the feasibility and reliability of the proposed parameter optimization method. In underground mining, blasting effect is a key factor influencing production efficiency. Taking a specific hard rock mine as the engineering backdrop, a coupled LS-DYNA/PFC numerical modeling approach was adopted to develop a 3D-model for simulating the blasting process. To investigate the influences of key blasting parameters on blasting outcomes, systematic variations were conducted for three bottom-hole spacing levels, four row spacing levels, and three blasthole diameter levels. The results indicated that different parameter combinations exhibited distinct performance advantages in terms of core indicators, including rock mass block volume, rear-row blasthole damage, and underbreak volume. To achieve the optimal comprehensive blasting effect, a multi-index comprehensive evaluation model was further established based on the AHP-entropy method. The AHP-entropy method incorporates two primary indexes (blasting quality and blasting cost) and five secondary indexes (Maximum block size, Large block rate, underbreak volume, damage rate of rear-row blastholes, and unit explosive consumption). This hybrid AHP-entropy framework effectively integrates the advantages of objective and subjective weights of the indexes, rendering the model’s evaluation results more scientifically rigorous. the optimal combination of blasting parameters was determined by the AHP-entropy method: the blasthole diameter is 65 mm, the row spacing is 1.3-1.5 m, and the bottom-hole spacing is 1.5-1.8 m. Field blasting tests verified that the theoretical evaluation and numerical results are highly consistent with practical observations, demonstrating the high feasibility of the proposed blasting optimization method. This research method provides valuable references for the mining operations of similar underground metal mines.