3rd International Workshop on Coal Pillar Mechanics and Design, Morgantown, West Virginia, July 26, 2010
Authors: Tom Vandergrift and David Conover (AAI)
Currently accepted longwall abutment gate-road design criteria result in very large pillar sizes under deep cover. This leads to ventilation challenges, and makes it difficult for development to keep pace with longwall retreat. One of the most widely accepted gate-road pillar design approaches is the ALPS (Analysis of Longwall Pillar Stability) program. It has been speculated that ALPS overestimates the load transferred to the gate roads under deeper cover. A recent instrumentation program at a deep western U.S. longwall mine allowed for a direct comparison of measured side abutment loads and those assumed in ALPS. The results may help to explain why some pillars with low ALPS stability factors perform adequately, and may spur further research into more efficient gate-road design under deeper cover.