Effects of decoupling and simultaneous detonation on blast vibrations
Conference
·
OSTI ID:398355
- Laurentian Univ., Sudbury, Ontario (Canada)
- Royal Oak Mines Inc., Timmins, Ontario (Canada). Timmins Div.
The need for blast vibration monitoring can be attributed to a combination of three factors: structural damage, blast design and human annoyance. Traditionally, vibration damage criteria are prescribed in terms of peak particle velocity (PPV), as measured or predicted in the ground surrounding a blast. The PPV in the vicinity of a blasthole is strongly influenced by the quantity of the explosive per delay. In general, the existing prediction models give reliable results but fall short of addressing the change in PPV when the charge is decoupled and/or distributed. Therefore, a study was designed with the following objectives: To develop a model for prediction of PPV when an explosive charge is decoupled and to examine the adequacy of the existing models in predicting the PPV, when more than one hole is initiated on the same delay number. Blasting experiments were conducted on large boulders of quartzite and a rock-like material called Hydro-Stone. The blast vibrations were monitored with OMNI PROBE 1200. It was observed that PPV decreased with a reduction in coupling ratio, which can be accounted for by incorporating a decay factor into a standard prediction equation. The PPV generated by the simultaneous firing of multiple holes was less than the predicted values. The measured PPV at any one point was found to be less than double the PPV for a single blasthole. When the number of blastholes fired simultaneously exceeded four, the increase in the PPV at any one point was significant. This provided a quantitative explanation to the common observation of minimum damage produced by the simultaneous firing of perimeter holes in mining operations.
- OSTI ID:
- 398355
- Report Number(s):
- CONF-9502142--
- Country of Publication:
- United States
- Language:
- English
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