TY - GEN
T1 - A numerical investigation of the effect of blasthole delay in rock fragmentation
AU - Mortazavi, A.
AU - Salmi, E. F.
PY - 2010/12/1
Y1 - 2010/12/1
N2 - One of the main objectives of all blasting operations is good fragmentation. Rock fragmentation by blasting is a complicated process which involves consecutive loading phases. Additionally the initiation of multiple holes in a blasting operation adds complexity to the process. The intention of this study is to investigate the effect of delay between blastholes in a qualitative manner and in an actual bench scale. The 3D finite difference code (FLAC 3D) was used to model multiple blasthole initiation in a typical bench. The blast loading history was simplified and applied to the blasthole walls. Accordingly, the interaction of explosive energy transferred to rock from each hole was examined as a function of blast-hole delay. A Mohr-Coulomb material model was used for host rock to allow for plastic failure calculations. The conducted numerical study describes the role of delay time in blasting in a qualitative manner. The obtained results show that, at the end of stress wave loading phase, long delays cause the burden to be under a higher stress state and closer to the rock mass failure envelope. In the case of 0 ms delay, in spite of high and fast delivery of energy to the rock mass, the final stress state in the burden is fairly lower than the 7 ms delay case. In other words, in this case, the burden material has a longer stress path to reach the rock mass failure envelope.
AB - One of the main objectives of all blasting operations is good fragmentation. Rock fragmentation by blasting is a complicated process which involves consecutive loading phases. Additionally the initiation of multiple holes in a blasting operation adds complexity to the process. The intention of this study is to investigate the effect of delay between blastholes in a qualitative manner and in an actual bench scale. The 3D finite difference code (FLAC 3D) was used to model multiple blasthole initiation in a typical bench. The blast loading history was simplified and applied to the blasthole walls. Accordingly, the interaction of explosive energy transferred to rock from each hole was examined as a function of blast-hole delay. A Mohr-Coulomb material model was used for host rock to allow for plastic failure calculations. The conducted numerical study describes the role of delay time in blasting in a qualitative manner. The obtained results show that, at the end of stress wave loading phase, long delays cause the burden to be under a higher stress state and closer to the rock mass failure envelope. In the case of 0 ms delay, in spite of high and fast delivery of energy to the rock mass, the final stress state in the burden is fairly lower than the 7 ms delay case. In other words, in this case, the burden material has a longer stress path to reach the rock mass failure envelope.
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M3 - Conference contribution
AN - SCOPUS:84859812607
SN - 9780415482967
T3 - Rock Fragmentation by Blasting - Proceedings of the 9th International Symposium on Rock Fragmentation by Blasting, FRAGBLAST 9
SP - 363
EP - 369
BT - Rock Fragmentation by Blasting - Proceedings of the 9th International Symposium on Rock Fragmentation by Blasting, FRAGBLAST 9
T2 - 9th International Symposium on Rock Fragmentation by Blasting, FRAGBLAST 9
Y2 - 13 September 2009 through 17 September 2009
ER -