切槽孔掏槽爆破机理动态焦散线实验研究

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

为研究切槽孔掏槽爆破爆生裂纹起裂、扩展及其与空孔相互作用机理,采用数字激光动态焦散线实验系统,对比分析了切槽孔与普通孔掏槽爆破裂纹扩展速度及动态应力强度因子的变化规律。实验结果表明:与普通孔相比,切槽孔掏槽爆破主裂纹在起裂阶段,应力强度因子出现最大值;扩展阶段,裂纹近似匀速稳定扩展,应力强度因子波动范围较小,整体数值较大;与空孔相遇阶段,3条主裂纹相互贯通,相应地产生3条次生裂纹,并与主裂纹相向运动,提高了各自的扩展速度和应力强度因子。空孔处破碎较严重,其补偿空间得到充分利用,有利于提高掏槽效率。

In this study,digital laser dynamic caustics system being used,notched and non-notched borehole cut blasting are compared in crack propagation velocity and dynamic stress intensity factor to study the crack initiation,propagation,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 initiation,have approximately constant velocity with the larger stress intensity factor in the narrower range in crack propagation,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＂.