Analysis of damage characteristics and optimization of fan-holes blasting design under high in-situ stresses

In deep mining, the rock mass is characterized by high in-situ stress, which makes the traditional drilling and blasting methods difficult, inefficient, and costly. To overcome this difficulty, LS-DYNA software was used to simulate the process of fan-hole blasting under in-situ stress. The blasting design was carried out for a 932.5 m depth of rock mass in combination with the actual mining conditions. The results show that the damage extent has an obvious correlation with in-situ stress level. The peak particle velocity, effective stress, and kinetic energy for rock mass were reduced under in-situ stress and the ore fragmentation was more heterogeneous. The effect of hole-bottom spacing and minimum burden on the mechanical response obtained from the simulation was analyzed by the response surface method, and the best blasting cost and effect were obtained with a hole bottom spacing of 2.48 m and a minimum burden of 1.6 m using the desirability function. This study can provide solutions to the fan-holes blasting difficulties that are encountered with deep mining.