METHOD OF BREAKING DOWN ROCK IN QUARRIES Russian patent published in 1995 - IPC

FIELD: mining. SUBSTANCE: this method prescribes boring, charging and shooting additional holes prior to drilling breaking holes, boring additional holes in parallel groups distance between which should be preset according to ratio of L = 2Kd (in terms of meters), where K represents coefficient defining distance covered by stress wave that governs development of microfractures and accounting for 50 to 75 and d is diameter of explosive charge cylinder in meters. Specific rate of consumption of explosives in additional holes ranges from 1.0 to 1.3 of that in breaking holes. Disclosed method further prescribes drilling holes in each additional group of wells in single diagonal row and instantaneously shooting explosive charges in all additional holes. Another possible version prescribes drilling holes in each additional group in several diagonal rows, shooting charges starting from central row and extending to periphery and exploding appropriate rows of all groups instantaneously and at same time. Shooting in additional holes in shoulder rock causes initiation of main cracks that converge in rock fracturing zone and thus enables water to run down via cracks into rock fracturing zone and then shoulder bottom. EFFECT: greater efficiency of breaking owing to reduction in strength of rock and extent of flooding. 3 cl, 3 dwg