周边空孔与炮孔间距对爆破时围岩断裂损伤的影响OA北大核心CSTPCD

In order to explore the influence mechanism of spacing between empty hole and blast hole on blasting crack propagation and surrounding rock damage in perimeter blasting,on the basis of theoretical analysis of the influence of borehole spacing on reflection of oblique incident stress waves and unloading waves on surrounding rock stress distribution,numerical models were combined to analyze the changes of fracture and damage under different blasthole spacing during perimeter blasting with or without empty hole.Results show that the spacing between empty hole and blast hole is a key fac-tor in exerting the empty-hole effect.If the spacing is small,the energy utilization rate of explosives decreases,and the guiding effect of empty hole on crack propagation cannot be exerted,resulting in severe damage to surrounding rock.When the spacing is large,the reflection effect of empty hole on stress waves is weakened,and the empty-hole effect is not suffi-cient for the cracks between the two holes to penetrate each other,which cannot meet the excavation requirements.When the spacing between two blast holes is 800-1000 mm,the outcome of the empty-hole perimeter blasting is the best,and the addition of empty holes can increase the blasthole spacing by 30%.