The result shows that residual hole is resulting from rock extruding, and that residual length of hole can be reduced as application of divided charge and millisecond delay firing in hole.

• 研究结果表明:由于炮孔深部岩石的夹制作用,炮孔装药爆破后易产生一定量的残孔,而采用孔内装药分段微差爆破则能减少残孔长度,提高爆破效率。