Research and Application of Axial Staggered Charge Blasting Technology in Layered Rock Masses Under Deep-Hole Blasting

To solve the problems of high explosive consumption, coarse fragmentation, and low energy utilization efficiency in open-pit blasting of layered rock masses, an axial staggered charging technology is proposed. The core idea of this new technology is to adjust the explosive structure according to the thickness of layered rock mass by setting ‘in-hole axial spacing charge and inter-hole staggering space’. By inserting air decks within boreholes and alternately offsetting the explosive sections between adjacent holes, the spatial distribution and timing of energy release are effectively regulated, leading to a more uniform stress field and improved utilization of explosive energy. An on-site field experiment was conducted at the western-262 region of the Yanshan Iron Mine. Both the rock fragmentation process, the vibration velocity and the distribution of rock fragment size were analyzed. The results show that, when compared with the ordinary continuous blasting technology, the axial staggered charging technique can effectively reduce the flyrock distance and produce a more compact muckpile, while peak vibration velocity is reduced by approximately 8.7% and explosive consumption is decreased from 0.19 kg/t to 0.17 kg/t, representing a decrease of about 10.5%. Moreover, the rock fragments exhibited a more uniform fragmentation size under the axial staggered charging technique, and the rock fragment size beyond 0.5 m decreased significantly. This study indicates that the axial staggered charging technology can reduce both the explosive consumption and rock fragments size in layered rock masses, providing a practical and technically feasible approach for optimizing deep-hole blasting design in such strata.