Optimization of Blasting Parameters for Open-pit Bauxite Mine under Interbedded Mudstone Geological Conditions

In mudstone interbedding geological formations, critical blasting parameters including the distance between blast holes and mud layers, borehole spacing, row spacing, and initiation delay intervals significantly impact explosive energy utilization efficiency and overall blasting performance in open-pit bauxite mining operations. To identify optimal blasting parameters for bench blasting in interbedded mudstone geology, representative rock samples were systematically collected from the target mining area, processed under standardized conditions, and subjected to comprehensive static mechanical testing to characterize fundamental geomechanical properties. Subsequently, a single-hole blasting simulation model for interbedded mudstone was developed using LS-DYNA to analyze damage characteristics and peak effective stress at varying distances (L) between the bottom of the blast hole and the mudstone interlayer, thereby determining the optimal L value. Furthermore, a multi-hole blasting simulation model for interbedded mudstone was established to extend the investigation. A comprehensive analysis was performed to evaluate damage characteristics, peak effective stress distribution, and peak vibration velocity under varying blast hole spacing (d₁), burden (d₂), and delay interval (T) configurations, ultimately identifying optimal parameter combinations. Field blasting experiments were subsequently conducted to validate the simulation findings. The results demonstrate that explosive energy dissipation becomes significant when blast holes are positioned near mud layers, with the optimal vertical distance from the hole bottom to the mud layer set at 1 m. For interbedded mudstone formations, the ideal blasting parameters are 3 m hole spacing, 2 m burden, and a 50 ms delay interval, achieving both effective rock fragmentation and minimized vibration impacts. These findings provide valuable guidance for precision blasting design in comparable open-pit mining operations with similar interbedded mudstone geological conditions.