井巷掏槽爆破中空孔效应的理论与试验分析

通过对含空孔掏槽爆破作用的机理分析以及对掏槽爆破中空孔的作用进行研究,从理论上得出了空孔的应力集中效应,应力集中效应随空孔直径的增加而增加;并且空孔大有利于反射拉伸波的破岩之结论.提出了用槽腔面积、循环进尺以及单位槽腔体积形成时间3个指标来评价掏槽爆破的经济技术效果,并用这些指标对不同空孔孔径的掏槽方式进行了现场对比试验分析与评价,结果表明:适当加大空孔孔径是提高巷道爆破掘进循环进尺行之有效的方法.

Theoretical and Experimental Study on Empty Hole Effect in Tunnel Cut Blasting

From the study of the mechanism of cut blasting with empty hole and the function of the empty hole, it is concluded theoretically that the empty hole has stress concentration effect which increases with the increase in the empty hole diameter, and the larger diameter empty hole is beneficial to the rock fragmentation by reflective stretching wave. It is proposed to use the indexes of the cut cavity area, advance per attack and forming time for unit cavity volume to assess the economic and technical performances of cut blasting. The results of making an on-site test analysis and assessment show that the proper enlargement of the empty hole diameter is an effective means to raise the advance of drifting cycle.