| 摘要 |
The present invention relates to a method for forming a parallel bore hole and a slant bore hole (or V-shaped V bore hole) together within the same area of a working face, and then blasting the working face by using a delay electric detonator. The method of this invention includes the steps of drilling a number of slant holes by a predetermined angle in the horizontal angle cut pattern or in the vertical angle cut pattern about the central zone of a working face, drilling a number of parallel cut holes within a projective area of the above mentioned slant holes; loading an electric detonator in the slant holes and an explosive material by indirect priming in the parallel cut hole up to the bottom of the slant holes; blasting the slant holes to form a slant free surface; blasting a center cut hole out of the parallel cut holes to form two free surfaces having a funnel shape; and sequntially blasting a middle cut hole and an outer cut hole out of the parallel cut holes to form a cubical space, and as a result, the drilling is achieved easily, the drilling time is reduced, the necessary quantity of explosives is low, and the blasting efficiency is high.
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