PERMFILE52240

• Permit No: M2001035
• IBM Index Class Name: Permit File
• Doc Name: TROUT CREEK QUARRY BLASTING INFORMATION
• Media Type: D
• Archive: No

~.
F..valuetion of Proposed Blasting a[ the ACA Riprap Quany near Buena Visa, C(
Velocity o/Particle Motion or Air Overpressure Plotted
with re8~12ct tO l,mR
1 CYCLE
n T
y 8ackgrounG
V ~ Noix Base
s ~i - une
a Peak
C Amplihrdw
Event Duration
r r
TIME
-~
Figure 2.2 -- Idealized Vibration or Air Overpressure Tirne-Intensity History Plot
The intensity of ground motion cart be measured in sevet•al ways. These measures include:
• Pat-ticle displacement
• Particle velocity
• Particle accelcratio[t
• Vibratiatfrequency
Displacement is a measure o:f ground particle travel distance or locatio» with respect to time.
Particle velocity measures the speed of movement and acceleration is the rate of velocity
changes. Vibration f~equcncy is a measure of how many nccillatinns a ground particle makes per
second of time. Frequency is reported in units of Hertz (Nz), which is equivalent to cycles per
second. i[ is lmponan[ ro note that [he frequency of motion is rclalivcly },igh wilhiu Ate near z~ua
t< 200 feet) and it attettuatcs to the ground's natural frequency with distance. The frequency of
oration, induced by the quarry blasting, will ]ikel}• range trom 30 to St) l~Iz in the granodiorite
for[natiott tltst supports the dam.
prerticrinn of Ctrnund Motion
Far many years, blasters and engineers have used empirical exponential decay relationships to
predict vibration magnitude based on distance and charge weight per delay. These equations use
dimensional similittrdr thPnry to define the relationship between ground vibration intensity
expressed as Peak Particle Velocity (PPV), distance and charge weight. Distance is typically
REVEY Associates. Inc. Page 3 July GUU t