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Blasting Impacts and Rock Slope Stability Assesmmt for Cottonwood Quarry in Grand Cmmty,CO <br /> Displacement is a measure of ground particle travel distance or location with respect to time. <br /> Particle velocity measures the speed of movement and acceleration is the rate of velocity <br /> changes.Vibration frequency is a measure of how many oscillations a ground particle makes per <br /> second of time. Frequency is reported in units of Hertz (Hz), which is equivalent to cycles per <br /> second. <br /> 3.2 Vibration Perception and Damage Criteria <br /> The average person is quite sensitive to ground motion, and levels as low as 0.50 mm/s (0.02 <br /> in/s) can be detected by the human body when background noise and vibration levels are low.A <br /> curve plotting intensities of ground motion and motion frequencies that will not cause cosmetic <br /> cracking in drywall and plaster-lath walls are shown in Figure 3.3. Vibration intensity is <br /> expressed as Peak Particle Velocity (PPV),which is simply the maximum speed that the ground <br /> moves while it temporarily shakes. Since ground-shaking speeds are very small,it is measured in <br /> inches per second (in/s). Frequency of motion or cycles per second is a measure of how many <br /> times a particle of ground moves back and forth (or up and down) in one second of time. <br /> Frequency is expressed in units of Hertz(Hz). <br /> The"safe limits"published by the US Bureau of Mines(USBM)in Report of Investigations(RI) <br /> 8507, are specifically intended to protect typical wood frame homes. Significantly higher PPV <br /> limits, ranging from 5.0 to 20 in/s, are used to protect buried pipes and other heavy civil <br /> structures. <br /> 254(1a) <br /> 203(5) <br /> v 1oz(4) <br /> USBM RI$507"Sate Level"Curve <br /> WB fads <br /> E RO W4 <br /> 50.8(2) <br /> PPV V 25.4(1) 19.0rrNs <br /> 1 20.3(.S) (�.FJ1NS} <br /> DyNd <br /> � 152(A) <br /> W 127rtr�s~ i <br /> U 10.2(.a) (ODD) <br /> i <br /> i <br /> Q s.t(.2) j1 f <br /> a 2 <br /> i <br /> 2.5 41) 1 2 4 6 B 10 20 30 40 00 80 100 <br /> FREQUENCY, Hi <br /> Figure 3.3—USBM"Safe Level"vibration curve from RI 8507 <br /> REVEY Associates,Inc. Page 6 April 2004 <br />