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Microseismic monitoring of a longwall coal mine. Volume 3 — Field study of mine subsidence
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800 feet from the source° See items 821172 and 821173 for volumes 2 and 3. Avail: NTIS, Sprir~field, Va, 22161 USA (PB 80-163397, or PB 80-163389 for set of 3) 821172 MICROSEI~MIC MONITORING OF A LOCK,WALL COAL MINE. VOLUME 2 - DETERMINATION OF SEISMIC VELOCITY Hardy, H R; Beck, L A US Bureau of Mines report OFR 30(2)-80, 31 Oct 1977, 232P Three methods were employed to evaluate seismic velocities: surface refraction s downhole, and transmission. In all cases the seismic sources were either located on surface (mechanical impact) or near-st~ace (exploslve charges), it was £ouma that a mechanical source could be conveniently utilized to determine shallow velocities and make bedrock-regolith interface depth determlnatlons. For deeper velocity determinations suitable explosive charge sources were required. In general, refraction data did not always plot in a linear manner and some subjective interpretation was
necessary. The downhole method was useful for incremental vertical evaluation, however, the transmission method provided the most consistent average vertical velocity data. See items 821171 and 821173 for volumes 1 and 3. Avail: NTIS, Springfield, Va, 22161 USA (PB 80-163~05, or PB 80-163389 for set of 3)
821173 MICROSEISMIC MONITORING OF A LONGWALL COAL MINE. VOLUME 3 " FIELD &TUDY OF MINE SUBSIDENCE Hardyj H R; Anani, B A; Khair, A W US Bureau of Mines report OFR 30(3)-80, 31 Oct l~?T7, 140P Presents the observed microseismic activity with surface subsidence. Comparative analysis of actual field results with data obtained using empirical and finite element techniques was carried out. There are marked differences with National Coal Board Data. See items 821171 and 821172 for vol~nes i and 2. Avail: NTIS, sprlr~field, Va, 22161 USA (PB 80-163413, or PB 80-163389 for set of 3)
800 feet from the source° See items 821172 and 821173 for volumes 2 and 3. Avail: NTIS, Sprir~field, Va, 22161 USA (PB 80-163397, or PB 80-163389 for set of 3) 821172 MICROSEI~MIC MONITORING OF A LOCK,WALL COAL MINE. VOLUME 2 - DETERMINATION OF SEISMIC VELOCITY Hardy, H R; Beck, L A US Bureau of Mines report OFR 30(2)-80, 31 Oct 1977, 232P Three methods were employed to evaluate seismic velocities: surface refraction s downhole, and transmission. In all cases the seismic sources were either located on surface (mechanical impact) or near-st~ace (exploslve charges), it was £ouma that a mechanical source could be conveniently utilized to determine shallow velocities and make bedrock-regolith interface depth determlnatlons. For deeper velocity determinations suitable explosive charge sources were required. In general, refraction data did not always plot in a linear manner and some subjective interpretation was
necessary. The downhole method was useful for incremental vertical evaluation, however, the transmission method provided the most consistent average vertical velocity data. See items 821171 and 821173 for volumes 1 and 3. Avail: NTIS, Springfield, Va, 22161 USA (PB 80-163~05, or PB 80-163389 for set of 3)
821173 MICROSEISMIC MONITORING OF A LONGWALL COAL MINE. VOLUME 3 " FIELD &TUDY OF MINE SUBSIDENCE Hardyj H R; Anani, B A; Khair, A W US Bureau of Mines report OFR 30(3)-80, 31 Oct l~?T7, 140P Presents the observed microseismic activity with surface subsidence. Comparative analysis of actual field results with data obtained using empirical and finite element techniques was carried out. There are marked differences with National Coal Board Data. See items 821171 and 821172 for vol~nes i and 2. Avail: NTIS, sprlr~field, Va, 22161 USA (PB 80-163413, or PB 80-163389 for set of 3)