The Massive Collapse of Coal Pillars -- Case Histories from the United States


A massive pillar collapse occurs when undersized pillars fail and rapidly shed their load to adjacent pillars which in turn fail. This chain reaction-like failure may involve hundreds, even thousands, of pillars and the consequences have been catastrophic. One effect of a massive pillar collapse can be a powerful, destructive, and a potentially hazardous airblast. On eleven recent occasions, massive pillar collapses have occurred in six southern West Virginia coal mines. Research was conducted at four mines where massive pillar collapses occurred. Geotechnical evaluations of roof rock, coalbed, and floor conditions were made. Evidence indicates that in each case a massive and competent roof rock unit was able to bridge a relativelywide span, creating a pressure arch. Eventually, the pressure arch apparently broke down, and the structural characteristics of the pillar system were such that sudden, massive pillar failures occurred. Data collected at the failure sites also indicates that all the massive collapses occurred where the pillars width-to-height ratio was 3.0 or less. Numerical modeling, supports the conclusions that the extent of the mined-out-area, the bridging capability of the main roof, and the width-to-height ratio of the pillars are probably all significant factors in the occurrence of massive pillar failures. -from Authors

Meeting Name

13th International Conference on Ground Control in Mining (1994: Aug. 2-4, Morgantown, WV)


Mining Engineering

Document Type

Article - Conference proceedings

Document Version


File Type





© 1994 Society for Mining, Metallurgy & Exploration Inc. (SME), All rights reserved.

Publication Date

04 Aug 1994

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