A Numerical Simulation Study of Focused Hydraulic Blasting in Coal Seams of Open‐Pit Mines

In the process of open‐pit coal mining, traditional blasting methods often lead to issues such as uneven fragmentation, difficult vibration control, and significant dust pollution. Addressing how to improve blasting techniques to better align with the production characteristics of open‐pit mining has been a focal point for both enterprises and scholars. This study combines focused energy blasting with hydraulic blasting through theoretical analysis and numerical simulation to address these challenges. The study theoretically explains the mechanisms by which stress waves and explosion‐generated gases fracture coal seams during blasting. It also investigates the role of focused hydraulic blasting in enhancing the effectiveness of coal seam blasting, demonstrating that this method can improve the effectiveness of blast‐induced stress, increase explosive utilization, and promote better crack development. Numerical simulations using ANSYS/LS‐DYNA were conducted to study the focused energy structure. The results indicate that four‐way focused blasting saves the most explosives and reduces the peak compressive stress by a small margin but significantly increases subsequent compressive stress, with a strain range that better meets the needs of open‐pit mine blasting. The four‐way focused blasting method was thus determined to improve coal seam blasting outcomes. Further simulations to optimize the focused groove structure revealed that a groove shape with a 60° focusing angle and a focusing depth of 4R/5 produces the best blasting results. Both theoretical and simulation results confirm that focused hydraulic blasting can effectively reduce mining costs, control blasting vibrations, and reduce dust emissions, contributing positively to the development of environmentally friendly mines.