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Review of Blasting Operations at Denver Brick Company's Golden Mine <br /> Abbreviations: <br /> SH=Shear wave.horizontal <br /> SV=Shear wave,vertical <br /> R =Rayleigh wave <br /> P =Compressional wave <br /> • ---- <br /> SH <br /> SV <br /> Charge or other <br /> tmpWanre <br /> GsWrGertce <br /> Figure 2.1 - Standard Vibration Waves <br /> The characteristics of ground motion can be measured in several ways: <br /> • Particle displacement <br /> • Particle velocity <br /> • Particle acceleration <br /> • Vibration frequency <br /> Displacement is a measurement of ground particle travel distance or location with respect to <br /> time. Particle velocity measures the speed of movement and acceleration of the rate of velocity <br /> changes. Vibration frequency is a measure of ground particle oscillations occurring per second <br /> of time. Frequency is reported in standard units of Hertz(Hz),which is equivalent to cycles per <br /> second. <br /> Standard industry damage criteria and "safe levels"of ground motion are strictly based on <br /> particle velocity and frequency of motion.This response of ground motion to humans or <br /> structures is primarily influenced by ground motion velocity and duration of the motion. Vibration <br /> intensity is expressed as Peak Particle Velocity(PPV).This ground motion (shaking) speeds are <br /> measured in inches per second, because of their speeds being generally low. <br /> Frequency of motion is important because, unlike earthquakes where frequency of motion is <br /> quite low, cycles of ground particle shaking (frequency)caused by blasting usually occurs at 10 <br /> to 50 Hz. Since ground particles are shaking so quickly (oscillating)they do not move very far. <br /> As shown in Figure 2.2, the intensity and frequency of vibrating ground particles or changes in <br /> air-pressure can be determined when these events are measured and plotted with respect to <br /> time. <br /> 7 <br />