Abstract
The task of the article is to determine the influence of the blasting charge power on the intensity of preliminary destruction of the blasting block mass at long delays. Increase of the destruction radius r from the blasthole charges action at diagonal pattern of hole-by-hole blasting, caused by change of explosive charge energy or rock properties, decreases the number of stress waves passing in the vicinity of specific blast holes. They cause the rock disturbance in the pre-destruction area due to increasing of explosion energy absorption in the area of blasthole charges destruction. However, at the same time, the value of the predestruction factor increases. The calculation shows that 3.5 times increase of the blasthole charge destruction radius, reduces in 1.36 times the number of stress waves passing through the vicinity of specific blasthole charges, but the factor of pre-destruction intensity increases tenfold and the total impact of these factors – by a factor of 8.
Highlights
Blasting rock destruction is characterized by one type of destruction – separation under the tensile stresses action from the compression wave action in the rarefaction phase
The qualitative indices of explosions in the quarries of Navoi Mining and Metallurgical Plant using non-electric initiation systems of the ISKRA type are characterized by the compact form of disintegration of the exploded rock mass, which contributes to losses and dilution reduction; the decrease of the coarse-grained rock yield; improvement of the quality of the ledge bottom finalization and seismic effect decrease
The improvement of the above mentioned parameters is explained by multiple explosive loading of the rock mass during hole by hole blasting with long delays (150 ms and more), which contributes to the formation of additional exposed cuts, increasing the impact of blasted rock flows
Summary
Blasting rock destruction is characterized by one type of destruction – separation under the tensile stresses action from the compression wave action in the rarefaction phase. This leads to formation of a fracture system cutting the rock mass [1, 2]. The improvement of the above mentioned parameters is explained by multiple explosive loading of the rock mass during hole by hole blasting with long delays (150 ms and more), which contributes to the formation of additional exposed cuts, increasing the impact of blasted rock flows. The task has been put to determine the blasting charge power impact on intensity of preliminary destruction of an explosive block mass
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