Influence of detonator delay scatter on rock fragmentation by bunch-holes blasting

Bunch-holes blasting (several blastholes arranged in a bunch with short spacing and detonated simultaneously to form large common crater) is typically used underground mines increase efficiency under single free surface. Considering the low accuracy of pyrotechnic detonators, which are commonly Chinese mines, bunch-holes same nominal times actually short-delay blasting, actual delay intervals induced by scatter detonators can lead unsuccessful bunch-hole seriously affects rock fragmentation. In this study, theoretical analysis firstly conducted explore mechanism formation time new surface defined as critical interval holes. Then, formula forming deduced determine blasting. detonator, probability method quantitatively analyse successful different detonators. Field experiments performed verify results. This research demonstrates that detonator increases, generally decreases. addition, charge length also has an impact on probability, positively correlated but not dramatic scatter. Hence, it recommended use high-precision or low-segment for ensure quality cutting