RESEARCH ON THE APPLICATON OF STRESS CONCENTRATION CONTROLLED BLASTING TO DEMENSYION STONE QUARRYNG

Stres concentration controlled blasting" for dimension stone quarrying contains two key parts:easy and convenient notching technique; safe and cheap low explosives. Rocks are brittle. Notching on rocks is a common interested problem to study, It can be Known from Griffith's theory that at the tip of cracks the stress field shows the singularity of r-1/2, that is to say, it possesses the property ot high stress concentration. In dimension stone quarrying by " stress concentration controlled blasting ", the notches are cut by hand rock brills, drilling the boreholes first and cutting the notches afterwards. The notching period is only 1/15 ¹/20 of the drilling time either on granite or on marble. The aulhor considers that mechanic notching will be the inexorable trend for future development. The reaction type for exploding materials-explosion or deflagration-is determined to a great extent by the exciting style, the combustion initiation.