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U <br /> Vibration and Air Blast <br /> Peak Particle Velocity <br /> inches per second Nature of Damage <br /> 12 Fall of rocks in unlined tunnels <br /> 7.6 50% Probability of major plaster damage <br /> 5.4 50% Probability of minor plaster damage <br /> 2.8-3.3 Threshold of damage from close-in blasting. <br /> 4 2.0 Safe blasting criterion for residential structures <br /> recommended by U.S. Bureau of Mines. <br /> I <br /> Figure 26-D.Damage levels from ground vibration as a function of peak particle velocity <br /> of ground motion near structures. Perceptible motion level to people Is about 0.02 ips. <br /> RELATIONSHIP OF NOISE LEVEL TO TEMPERATURE PROFILE <br /> Early Morning Mid Morning Late Morning Early Afternoon <br /> 0 <br /> Clouds may form at <br /> top of inversion if <br /> enough moisture is <br /> present Q <br /> A. B. C. D. <br /> Temperature <br /> A. High and low temperature inversions present — sound intensification results <br /> B.Lower inversion partially disappears— sound intensity near source diminished— focusing <br /> at larger ranges <br /> C. Surface temperature exceeds highest upper air temperature — sound not returned to <br /> surface by refraction <br /> D. Temperature inversions wiped out — upward refraction causes minimum sound levels at <br /> all distances <br />