Reasearch on and proposal for proper design methods for cut hole group when drilling & blasting roadways in rock

Abstract

A complete blasting passport usually consists of 3 groups of blastholes: Cut holes, auxiliary holes and contour holes. The cut hole group is the first group which is detonated to create a second free surface on the roadway face and facilitate the detonation of other blasthole groups. The blasthole utilization coefficient (or efficiency) of a blasting passport largely depends on the depth of the detonation of the cut hole group. However, in reality, the the design for the cut hole group in our country has not really been focused on. The designer often chooses the blasting parameters based on experience, sometimes the error is very serious when there is no method and reference parameters for the selection and calculation of an appropriate cut hole group.

In this article, based on the synthesis and analysis of the cut hole group using methods used in Vietnam commonly; Some designs have been proposed to meet with different blasting conditions for roadways in rock in underground mining. Finally, based on the theoretical research and the results of the graph analysis, which are obtained by analyzing the data compiled from the practical research, the parameter calculation principle for cut holes designs has been proposed. This is considering as a scientific basis for developing a software which can automatically design drilling & blasting passports in AutoCAD.