Longwall gate road roof instability and methods of control in the lower kittanning coalbed of central Pennsylvania. Information circular/1992

The report presents the results of a cooperative study between BethEnergy Inc., Ebensburg, PA., a central Pennsylvania coal mining company, and the U.S. Bureau of Mines, to investigate longwall development entry roof instability. In-mine mapping of geologic and deformational features was conducted to reveal the major ground control problems encountered during gate road development. Underground measurements were made to delineate the in situ stress field and its effect on cutter roof failure. In addition, mining-induced pillar load monitoring was used to indicate development loading on variously dimensioned gate road pillars and to determine if pillar yielding occurred. Finally, visual observations of a variety of roof control methods determined the most effective support elements for controlling cutter roof failure.