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Agriculture, NIOSH Research Projects						Print
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										April 1997
DHHS (NIOSH) Publication Number 97-124
97-124 Cover
A massive pillar collapse occurs when undersized pillars fail and rapidly shed their load to adjacent pillars, which in turn fail. The consequences of these chain-reaction failures can be catastrophic. One effect of a massive pillar collapse can be a powerful, destructive, and potentially hazardous airblast. Thirteen recent massive pillar collapses have been documented in West Virginia, Ohio, Utah, and Colorado. Data collected at the failure sites indicate that all of the massive collapses occurred where the pillar width-to-height (w/h) ratio was 3.0 or less and where the Analysis of Retreat Mining Pillar Stability Factor was less than 1.5. The unique structural characteristics of these pillar systems apparently result in sudden, massive pillar failures, rather than the more common slow “squeezes. The field data, combined with theoretical analysis, provide the basis for two partial-extraction design approaches to control massive pillar collapses. These are the *containment* approach and the *prevention* approach; practical examples are provided of each.
Agriculture, NIOSH Research Projects
							
					
							Last Reviewed:  April 21, 2017						Source: 	National Institute for Occupational Safety and Health
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