Modifying Sadov’s Empirical Formula for Group-Hole Blasting in Open-Pit Mine Conditions

Sadov's formula is widely used to solve the seismic wave velocity problem of single-hole blasting in calculations in blasting engineering. There is a significant difference between the calculated results for group-hole blasting and the actual situation in an open-pit mine. The modification and application of Sadov's formula for group-hole blasting in open-pit mines is discussed in this paper. First, the insufficiencies of Sadov's formula under the condition of group-hole blasting in an open-pit mine are analyzed. A theoretical derivation method for modifying the maximum charge coefficient is proposed. Second, blasting vibration data of the Hejing limestone mine of Guangxi Huarun Cement (Pingnan) Co. Ltd., obtained by onsite monitoring, are analyzed. The vibration data of the single-hole blasting are processed by linear superposition and fitting. The difference between the superposition results of the same single-hole vibration signal and different single-hole vibration signals and the onsite monitoring data is compared and analyzed. A modified expression of Sadov's formula is obtained. The onsite blasting parameters of the group-hole blasting are verified. Finally, the safety distance problem of the grouting curtain in blasting construction is solved using the modified Sadov's formula. The results show that the modification scheme of maximum charge Q in Sadov's formula is determined through theoretical analysis and formula derivation. The peak vibration velocity of the group hole blasting suitable for the Pingnan mining area is deduced, and the correctness of the peak vibration velocity is verified.