Application study on two-step cutting technology for rock drifting

In order to solve the problems of low utilization rate of blasthole, high boulder yield and long casting distance in rock roadway excavation of Yangmei No.1 coal mine, the two-step cutting technology is applied in rock drifting.Based on the analysis of rock-breaking mechanism of two-step cutting, the radius formulas of fragmentation zone and crack zone formed by explosive explosion in rock are derived.The blasting parameters of the two-step cutting are determined, including the key parameters of the first and second order cutting notch spacing and hole bottom spacing, and are applied in the field.Field test results show that compared with the original scheme, the utilization ratio of blasthole increases from 81% to 90%, the boulder yield decreases by 72%, the casting distance decreases by 29%, and the monthly footage increases by 50% from 60 meters to 90 meters.The application results show that the two-step cutting technology has good adaptability and high technical and economic effects, which can provide reference for rapid tunneling of the same type of roadway.