Evaluation of Seismic Potential in a Longwall Mine with Massive Sandstone Roof Under Deep Overburden

Details

• Personal Author:
  Su WH ; Van Dyke MA ; Wickline J
• Description:
  Geological factors and mine design contribute to ming induced seismic activity, and this is especially true in longwall mining. Massive rock units are a key cause of seismic activity due to catastrophic failures that release large amounts of energy. Other factors, such as overburden depth, panel design, pillar design, rock strength, and proximity of the massive rock unit to the coal seam, all have a role in the potential and size of a seismic event. A recent seismic event was recorded by a deep longwall mine in Virginia at 3.7ML on the local magnitude scale and 3.4 MMS by the United States Geological Survey (USGS) in July 2016, which had no impact on the mining operations. Further investigations by NIOSH and Coronado Coal researchers have shown that this event was associated with geological features that have also been associated with other, similar seismic events in Virginia. Detailed mapping and geological exploration in the mining area has made it possible to forecast possible locations for future seismic activity. In order to use the geology as a forecaster of mining-induced seismic events and the energy potential, two primary components are needed. The first component is a long history of recorded seismic events with accurately plotted locations. The second component is a high density of geologic data within the mining area. In this case, 181 events of l .OML or greater were recorded by the mine's seismic network between January, 2009, and October, 2016. Within the mining area, 897 geophysical logs were analyzed from gas wells, 224 core holes were drilled and logged, and 1,031 fiberscope holes were examined by mine geologists. From this information, it was found that overburden thickness, sandstone thickness, and sandstone quality contributed greatly to seismic locations. After analyzing the data, a pattern became apparent indicating that the majority of seismic events occurred under specific conditions. Three maps were created using MineScape geological mapping software. MineScape deploys an interpolator known as FEM (finite element method) and is based on a series of gridded triangles to forecast the probability and magnitude of an event if a particular panel were to be mined. The forecast maps have shown accuracy of within 74%-89% when compared to the recorded 181 events that were 1.0 ML or greater when considering three major geological criteria of overburden thickness of 1900 feet or greater, 20 to 40 feet of sandstone within 50 feet of the Pocahontas number 3 seam, and a longwall caving height of 15 feet or less. [Description provided by NIOSH]
• Subjects:
  Geology Mining Occupational Health Safety
• Keywords:
  Analytical Instrumentation Analytical Models Boreholes Cables Environmental Stress Environmental Technology Geologic Models Ground Control Ground Monitoring Ground Stability Load Monitoring Longwall Mining Measurement-equipment Monitoring Systems Pillar Design Pillar Mechanics Pressure Testing Retreat Mining Rock Bolts Roof Bolts Roof Supports Roof Support Systems Safety Research Strata Control Underground Mines

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• Series:
  Mining Publications
• ISBN:
  9780873354561
• Publisher:
  Society for Mining, Metallurgy & Exploration
• Document Type:
  Text
• Genre:
  Proceedings
• Place as Subject:
  OSHA Region 3 ; Pennsylvania ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  PMRD - Pittsburgh Mining Research Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  21-26
• NIOSHTIC Number:
  nn:20050421
• Citation:
  Proceedings of the 36th International Conference on Ground Control in Mining, July 25-27, 2017, Morgantown, West Virginia. Mishra B, Lawson H, Murphy M, Perry K, eds. Englewood, CO: Society for Mining, Metallurgy & Exploration, 2017 Jul; :21-26
• Editor(s):
  Mishra B; Lawson H; Murphy M; Perry K
• Federal Fiscal Year:
  2017
• NORA Priority Area:
  Mining
• Peer Reviewed:
  False
• Source Full Name:
  Proceedings of the 36th International Conference on Ground Control in Mining, July 25-27, 2017, Morgantown, West Virginia
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:3dabf48efbe2433b32a3fb82e9e220c342a6f0bd34877b274d7052eff3334ff2f121ff298c887a07020ef8ac1807147999dd1e551b6e1f3b69ef74f2d55e76f8
• Download URL:
  https://stacks.cdc.gov/view/cdc/227554/cdc_227554_DS1.pdf
• File Type:
  [PDF - 1.10 MB ]