Influence and Optimization Design of Step Blasting on Slope Stability in Open-pit Mines

Aiming at the problem of unstable blasting effects and damage to slope stability caused by factors such as large differences in rock strata hardness, complex geological structures, harsh hydrological and climatic conditions and others during the open-pit mine step blasting operations in Zhundong mining area, a slope stability analysis model is constructed by adopting finite element method and discrete element method, the action mechanism of blasting vibration, flying stones, and shock waves on rock mass is systematically discussed. Optimized and designed measures include adjusting drilling parameters such as hole depth, hole diameter, hole spacing, and row spacing to adapt to differences in rock strata hardness, accurately controlling the explosive loading capacity to implement segmented differentiated geological charges, adopting the joint tiny difference detonation technology in holes and between holes to optimize the detonation sequence, and applying a combination process of step deep hole tiny difference blasting and presplitting blasting. The engineering application verification shows that after optimization, the blasting vibration speed is decreased from 1.64 m/s to 1.16 m/s, the flying distance of flying stones is reduced from 120 m to 90 m, the slope stability coefficient is improved to 1.26, the occurrence rate of slope collapse is decreased from 5% to 2.5%, and the blasting cost is decreased from 800 000 yuan to 750 000 yuan, achieving synchronous improvement in operation safety, stability, and economy.