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Descripción
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| This work investigates some suggested methods for blast vibration monitoring on a hard surface based on 53 tests on a vibration exciter. Errors in the measurement attributable to coupling have been described as function of frequency by the rock-to-mount (or coupling) transmissibility ?ie ratio of the velocity of the vibration sensor mount to the velocity of the rock motion. Transmissibility has been measured from 2 to 200 Hz, at two vibration levels (5 and 20 mm/s), in four seismographs. Attachment methods with an anchor, thermal adhesive and gypsum plaster, allow stiff rock-to-mount-coupling. They ensure accurate measurements (errors below 0.3 dB) for frequencies commonly found in blasting (below 100 Hz) irrespective of the mount characteristics and the vibration level. Free laid mounts and sandbagged vibration sensors lead generally to a poor, weak coupling. Errors are non linear errors with the input velocity ?ie the operating frequency window narrows as the velocity of the ground increases. Free mounts follow ground motion acceptably well (error up to 0.4 dB) at both vibration levels and frequencies below 15 Hz. At higher frequencies, free mounts lead to the largest distortions with expected errors ranging from 0.8 to 6.6 dB. Sandbagging limits the expected errors below 1.3 dB, but it does not prevent large errors that can be up to 4.5 dB. In these conditions both frequency and velocity should be considered together to assess the measurement errors instead of the expected accelerations as it is currently made. | |
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Internacional
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Si |
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Nombre congreso
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11th International Symposium on Rock Fragmentation by Blasting |
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Tipo de participación
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960 |
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Lugar del congreso
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Sidney, Australia |
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Revisores
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Si |
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ISBN o ISSN
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978-1-925100327 |
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DOI
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Fecha inicio congreso
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24/08/2015 |
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Fecha fin congreso
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26/08/2015 |
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Desde la página
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545 |
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Hasta la página
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551 |
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Título de las actas
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Proceedings of the 11th International Symposium on Rock Fragmentation by Blasting |