Doludareva Y. Motivation of rational parameters blasthole charges to reduce the softening of rocks in the directed split

Object: The process of softening and destruction of solid media explosion. Objective: To improve the quality of the stone blocks formed directed cleavage by an explosion, due to the growing influence of gas flow of detonation products in the desired direction while decreasing the probability that a gas micro-cracks formed outside the line of division. Methods: A feasibility study of rational parameters of blasting on the basis of the theory of fracture and microcracks of rocks; physical simulation of fast processes of the theory of elasticity for the evaluation of the stress state of rock under impulse loads; feasibility study developed recommendations. Theoretical and practical results: theoretically the influence of the shape of an explosive charge on the distribution of stress and the effectiveness of directional splitting, theoretically justified influence of stress concentrators on the magnitude and distribution of stresses around them to create dynamic loads on the part of the mountain range to be destroyed; experimentally studied the effect of impulse loads posed in various ways, to change the strength of the material models after the pulsed exposure, theoretically and experimentally, the influence of boundary conditions on the edge of the reflecting unit in the fracture models under explosive loading; experimentally investigated the relationship changes in the strength of the samples after the explosive impact of the degassing process of the detonation products of educated and natural cracks, developed special design of the charges to separate blocks of the desired shape and size of the directed split. Novelty: theoretically grounded influence of the shape of the charge on the distribution of stress and effective direction of the split, the first time experimentally established the volume of detonation products, which fall into the cracks and the effect on the parameters of change in the strength of the rock after the blast impulse loads, the first time experimentally established parameters of the process changes in the strength of rock after the blast impulse load (abrupt decrease in strength and its subsequent recovery by the gradual closing of microcracks after complete or partial leaking of these gaseous products of detonation). The proposed design the explosive charge was pilot production test on the granite quarries of Kremenchug region, JSC "UKRAGROVZRYVPROM" specialized enterprise № 4 Kapustinskaya plot for the extraction of granite blocks JSC Elgran. Scope: open pit mining.