The influence of distant coal seam edges on seismic hazard during longwall mining
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ORIGINAL ARTICLE
The influence of distant coal seam edges on seismic hazard during longwall mining Łukasz Wojtecki
&
Iwona Gołda
&
Maciej J. Mendecki
Received: 14 April 2020 / Accepted: 5 October 2020 # The Author(s) 2020
Abstract Underground coal seam mining has been carried out in the Upper Silesian Coal Basin, Poland, for many years and with a simultaneous increase in exploitation depth. Frequently, coal seams are not fully extracted due to numerous reasons which lead to their edges and remnants remaining in the rock mass. Even in the case of the full extraction of a coal seam, mining usually ends at the border of a protecting pillar to protect underground or surface objects, sometimes at the border of the mining area, or some distance from the old goaf or high throw fault. Extraction of subsequent coal seams in
an analogous range results in a cluster of coal seam edges remaining. In the vicinity of the mentioned remainders, the disrupted stress distribution is expected. The infraction of the aforementioned equilibrium repeatedly results in the occurrence of strong mining tremors. The observations from the studied coal seam no. 408’s longwall panel indicated that mining works are able to disturb the present stress-strain equilibrium in the area of the edges of other coal seams, even if they are located at a greater vertical distance away. The seismological parameters and distributions have been applied for this purpose.
Highlights We reviewed a catalogue of mining tremors that occurred during longwall mining of coal seam no. 408 in one of the hard coal mines in the Upper Silesian Coal Basin, Poland. The seismological parameters and distributions have been applied to determine the correlation between edges of distant coal seams, located over the longwall panel, and occurrence of strong tremors. The performed analysis indicates influence of current mine workings on stressstrain equilibrium, established in the rock mass.
Keywords Seismic hazard . High-energy tremors . Coal seams edges
Ł. Wojtecki (*) Central Mining Institute, 1 Gwarków Square, 40-166 Katowice, Poland e-mail: [email protected] I. Gołda Faculty of Mining, Safety Engineering and Industrial Automation, Silesian University of Technology, 2 Akademicka Str, 44-100 Gliwice, Poland M. J. Mendecki Faculty of Environmental Sciences, University of Silesia in Katowic, 60 Będzińska Str, 41-200 Sosnowiec, Poland
1 Introduction Longwall mining is the most popular method of underground hard coal mining in Poland and in the world. It is due to the opportunity for the mechanization of mining system, which increases the concentration of extraction, the efficiency and the cost reduction. In longwall mining, the long wall of hard coal is mined by a shearer. It moves along the coalface, between two headings, called main gate and tail gate. The block of mined hard coal is called the longwall panel. In Polish conditions, longwall panels usually are approximately 150–300 m wide (longwall length) and approximately from hundreds of metres to 2000 m long. The sheare
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