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Geotechnical influences upon longwall mining

Abstract This paper describes geotechnical influences upon the planning, development and implementation of the longwall mining system. The effects of these factors have been assessed from a series of comprehensive investigations carried out in the South Wales and South Nottinghamshire Coalfields. All the investigations involved the setting up of monitoring sites employing specially designed instrumentation to monitor the parameters outlined in the paper. In addition, detailed structural and lithological investigations have been carried out involving underground mapping, diamond drilling and logging, geotechnical core logging and physical rock property determinations. This information has been brought together for each site and a characteristic deformation mechanism identified. These are presented in the paper with a series of three dimensional figures indicating the primary influences. The value of these types of studies is outlined in the paper both in the planning of subsequent extraction and as improvements to current operational systems.