Abstract: In view of high rate of large blast fragmentation, a big difficulty in long and medium-hole drilling and blasting, it is pointed out at the same time of taking integrated technical management measures, the key is to optimize the drilling and blasting parameters, adopt “minimum burden” blasting technique, renew the fragmentation process, and use new process of hole bottom reverse initiation; and optimize the initiation network and use safe, reliable and economically rational duplex initiation network.The production practice shows that under the guarantee of strictly controlled construction quality, the application of optimized blast fragmentation technique has radically solved the problem of high rate of large blast fragments, thereby achieving good technical and economical indexes.

Key words: Long and medium hole blast fragmentation technique, Optimization of structural parameters, Underground mining