Effects of Structural Faults on Ground Control in Selected Coal Mines in Southwestern Virginia

摘要

Two faults related to the Pine Mountain overthrust sheet in Buchanan County, VA, were investigated by the Bureau of Mines to determine their effect on ground control and to develop recognition criteria for prediction. Five underground mines encountering these faults were visited and mapped for structural information. The information, along with surface mapping, indicated that the Pistol Gap and Keen Mountain Faults show right-lateral, strike-slip faulting and bedding planes slippage, which can be projected linearly and vertically. These fault zones are up to 200 ft wide, with coalbed offsets up to 18 ft vertically, coalbed swags (depressions) up to 15 ft, and roof falls up to 20 ft high. Recognition criteria include bedding plane slips, coalbed offsets, fault gouge, coalbed swag (depressions or synclines), and disturbed bedding.