EXPERIMENTAL STUDY OF MECHANISM AND TECHNOLOGY OF DIRECTED CRACK BLASTING

The dynamic stress-fields and their distribution characteristics around boreholes in the directed crack blasting were measured with the dynamic photo-elastic laser holography apparatus and the uitradymamic measurement system. The directed crack mechanism and its mechanical model have been analysed and expounded. Through the 43 production experiments using slotted cartridges and the double triangle center cut-holes for directed crack blasting in underground rock drift, the resuits of which the rates of half-hole marks and efficiency of borehole,and the nonsmooth grades of the cut contours are 96%, 98% and 10cm respectively have been achieved.