The Journal of Explosives Engineering - July/August 2022 - 12
Results and Discussion
To characterize the site attenuation, a total
of 51 blasting events including 33 surface and
Figure 7. (a) Surface blast progression: numbers in each polygon shows the order of
blast, PPVs and distance to the closest borehole geophone; (b) site attenuation analysis.
18 underground blasts were recorded. Figure
7-a shows different stages of material removal
from the 4th bench. The numbers in each polygon
show the order in which the material was
removed. The maximum particle velocities and
distance to the closest borehole geophone are
also reported in each polygon. Figure 7-b plots
the results of the site attenuation analysis. The
vertical axis is the peak particle velocity from
each borehole sensor and the horizonal axis is
the scaled distance (i.e., distance to blast over
square root of charge weight). On this figure,
the surface blasts are shown with blue circles
and underground (UG) blasts with red circles.
As is evident on this figure, most events fell below
the 5 in/sec (127 mm/sec) vibration threshold
except for one surface blast (marked with a
star) that registered vibrations exceeding 10 in/
sec (254 mm/sec) at two of the borehole sensors.
The blast that resulted in vibrations above
10 in/sec (254 mm/sec) was the presplit that
was shot for the portal face. This presplit was
shot before the 13 surface blasts shown in figure
7-a. No rock fall or distress was observed in
the underground mine after this event. It is also
worth mentioning that the data points from the
underground blasts, though they appear to be
more scattered, follow the general trend of the
surface blasts. By fitting a power function to the
data, we developed 50% and 95% confidence
interval (CI) equations for vibration attenuation.
Both equations were updated after each blast,
but the 95% CI attenuation equation was used
Figure 8. (a) Sample waveforms from the same blasting event [top] dynamic crack movement, and [bottom] longitudinal channel of geophone; (b) crack
movement-PPV correlation.
12
The Journal of Explosives Engineering
July/August 2022
The Journal of Explosives Engineering - July/August 2022
Table of Contents for the Digital Edition of The Journal of Explosives Engineering - July/August 2022
From the Executive Director
Crack Displacement and Vibration Measurement of an Underground Portal
Product Spotlight
Industry News
Calendar of Events
Explosives, 100 Years Ago, More or Less
Chapter News
Blasting for Rescue Applications
29th Annual Photo Contest
Safety Talk
The Journal of Explosives Engineering - July/August 2022 - Intro
The Journal of Explosives Engineering - July/August 2022 - Cover1
The Journal of Explosives Engineering - July/August 2022 - Cover2
The Journal of Explosives Engineering - July/August 2022 - 1
The Journal of Explosives Engineering - July/August 2022 - 2
The Journal of Explosives Engineering - July/August 2022 - 3
The Journal of Explosives Engineering - July/August 2022 - From the Executive Director
The Journal of Explosives Engineering - July/August 2022 - 5
The Journal of Explosives Engineering - July/August 2022 - Crack Displacement and Vibration Measurement of an Underground Portal
The Journal of Explosives Engineering - July/August 2022 - 7
The Journal of Explosives Engineering - July/August 2022 - 8
The Journal of Explosives Engineering - July/August 2022 - 9
The Journal of Explosives Engineering - July/August 2022 - 10
The Journal of Explosives Engineering - July/August 2022 - 11
The Journal of Explosives Engineering - July/August 2022 - 12
The Journal of Explosives Engineering - July/August 2022 - 13
The Journal of Explosives Engineering - July/August 2022 - 14
The Journal of Explosives Engineering - July/August 2022 - 15
The Journal of Explosives Engineering - July/August 2022 - Product Spotlight
The Journal of Explosives Engineering - July/August 2022 - 17
The Journal of Explosives Engineering - July/August 2022 - Industry News
The Journal of Explosives Engineering - July/August 2022 - 19
The Journal of Explosives Engineering - July/August 2022 - Calendar of Events
The Journal of Explosives Engineering - July/August 2022 - 21
The Journal of Explosives Engineering - July/August 2022 - Explosives, 100 Years Ago, More or Less
The Journal of Explosives Engineering - July/August 2022 - 23
The Journal of Explosives Engineering - July/August 2022 - 24
The Journal of Explosives Engineering - July/August 2022 - 25
The Journal of Explosives Engineering - July/August 2022 - Chapter News
The Journal of Explosives Engineering - July/August 2022 - 27
The Journal of Explosives Engineering - July/August 2022 - Blasting for Rescue Applications
The Journal of Explosives Engineering - July/August 2022 - 29
The Journal of Explosives Engineering - July/August 2022 - 30
The Journal of Explosives Engineering - July/August 2022 - 31
The Journal of Explosives Engineering - July/August 2022 - 32
The Journal of Explosives Engineering - July/August 2022 - 33
The Journal of Explosives Engineering - July/August 2022 - 34
The Journal of Explosives Engineering - July/August 2022 - 35
The Journal of Explosives Engineering - July/August 2022 - 29th Annual Photo Contest
The Journal of Explosives Engineering - July/August 2022 - 37
The Journal of Explosives Engineering - July/August 2022 - Safety Talk
The Journal of Explosives Engineering - July/August 2022 - 39
The Journal of Explosives Engineering - July/August 2022 - 40
The Journal of Explosives Engineering - July/August 2022 - Cover3
The Journal of Explosives Engineering - July/August 2022 - Cover4
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