Borehole Layout Optimization and Numerical Analysis of Surrounding Rock Damage of Medium-deep Hole Cutting Blasting in Blind Shaft
The cutting blasting of blind shaft is only provided by the lower cutting roadway,and the rock clip is large.The selection of empty hole parameters is the key to improve the free surface,and the optimization of cutting hole layout parameters is an important way to improve the blasting effect.The hole arrangement parameters are optimized by the calculation model of empty hole effect and the damage zoning theory of rock.Based on the optimized hole arrangement parameters,the hole arrange-ment models of three kinds of straight hole cutting methods are established.The damage evolution,stress distribution and cavity range are analyzed,and the best scheme is verified on site.The results show that the empty hole arrangement in the radial frac-ture area can make the rock in the groove cavity fully destroyed,and the improved calculation formula of the hole arrangement parameters considers the influence of the free surface effect of the empty hole.The blasting cavity of the four-hole barrel cut is more uniform than that of the three-hole diamond cut,and the energy waste is less than that of the five-hole barrel cut.Based on the four-hole barrel cut,250 mm is the best spacing between the empty hole and the auxiliary hole.The field test of the best hole arrangement scheme shows that the optimized hole arrangement parameters can achieve good blasting effect.This study has guiding value for related blasting engineering design.
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