Abstract:  Currently, an underground lead-zinc mine in Yunnan is facing issues such as poor blastingelfects and high block rates , which significantly inerease economic costs. As mining operations continue,the ore and rock characteristics in dilferent areas become increasingly complex and variable, making asingle set of blasting parameters unsuitable for the mining operations. To optimize the blasting parametersand improve the blasting efect in on-site production, a series of uncoupled charge crater tests were con-ducted on the side of the 402 mining area of the mine, based on the Livingston blasting crater theory. Theoptimal values for the crater's hole depth, radius, critical depth, volume, hole spacing, and resistanceline were found to be 0.55 m, 0. 5 m, 1. 1 m, 0. 129 m’, 1.1 m, and 0. 85 m, respectively. After blas-ting, the fragments were collected, sereened, and classified by particle size. The R-R function was usedto predict the distribution of different particle sizes, and it was found that the R-R function could effec.tively predict the blasting fragmentation distribution. "The obtained parameters can provide theoretical support for optimizing blasting parameters in future field operations.

Key words: underground mining, blasting crater test, blasting fragmentation, optimal funnel parameters