Notched-borehole cut blasting study by the method of dynamic caustics

In this study,digital laser dynamic caustics system being used,notched and non-notched borehole cut blas- ting are compared in crack propagation velocity and dynamic stress intensity factor to study the crack initiation,propa- gation,and interaction mechanism with empty hole. Experimental results show that blasting cracks in notched borehole cut blasting,compared with those in non-notched one,have maximum dynamic stress intensity factor in crack initia- tion,have approximately constant velocity with the larger stress intensity factor in the narrower range in crack propaga- tion,and near the empty hole,three main cracks coalesce and correspondingly three secondary cracks generate,which propagate towards main cracks and in turn increase their propagation velocity and stress intensity factor. “ It is server damage around the empty hole,so compensation space of empty hole is efficiently used benefiting for increasing cut blasting efficiency. The results have theoretical reference significance for engineering”.