| 摘要 |
A rock blasting method is provided in which a series of aligned boreholes a re charged with explosives and air tubes in a predetermined pattern. The air tu be is a cylindrical flexible tube having a predetermined width and length to be fitt ed with the borehole. In one preferred form, each borehole is charged with the explosives and detonator with one air tube installed above the explosives. A stemming material is installed above the air tube. For example, in a 45-millimeter diameter an d 2.5 meter long borehole, the length of explosive charging is 0.8 meters, the co- operating charge weight was 0.648 Kg, the total amount of explosives 3.24 Kg, the leng th of the air tube 1.0 meter, the diameter of air tube 40 millimeters, and the length of stemming 0.7 meters. The explosives and air tube may be alternately charged along the borehole. The use of air tubes, charged above at least one explosive lay er allows a quantitative air decking in every blasthole. A reduction in detonation velocity and noise is observed in the field test. Also, the air-deck effect can be easily obtained: an increase in fragmentation rate with minimizing the production of boulders. A reduction in explosive usage is also achieved. |
