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- Pillars
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Results 11 - 20 of 35
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7/1/2007 - Conference papersObservations of pillar conditions in limestone mines showed that the presence of weak bands in the limestone can result in pillar damage. This study investigated the mechanism of failure caused by the presence of weak bands using numerical models.
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7/1/2007 - Conference papersNumerical modeling is used to evaluate the degree the pillar strength is increased with a rectangular pillar over a square pillar.
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5/1/2007 - Conference papers, Information CircularsA detailed evaluation of the multiple-seam experiences at Harris No. 1 Mine was done as part of NIOSH's nationwide multiple-seam mining case history database.
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Multiple-seam interactions are a major ground control hazard in many U.S. underground coal mines. NIOSH has been conducting research to develop better techniques for predicting the location and severity of multiple-seam interactions.
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5/1/2007 - Conference papersA survey of roof and pillar conditions in limestone mines has revealed that bench mining of the floor between pillars can cause instability in the pillars at the perimeter of the benched area. Numerical models were used to assess those effects.
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1/1/2007 - Peer reviewed journal articlesSome of the issues affecting pillar strength at low width-to-height ratios in hard, brittle rock are investigated. The results showed that the strength of slender pillars is more variable than that of wider pillars.
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8/1/2006 - Conference papersA survey of pillar conditions was carried out at 21 operating limestone mines that use the room-and-pillar method. Pillar instability is most likely caused by unfavorable geological structures in pillars with width to height ratios of less than 1.5.
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8/1/2005 - Conference papersResults show that the remnant upper seam structure's size can influence multiple seam interaction. Specifically, smaller critically loaded upper seam pillars appear more likely to cause lower seam ground control problems than wider pillars.
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8/1/2004 - Conference papersUnderground limestone mine roofs in Northern Appalachia can be subject to high horizontal stresses. A case study is presented showing that induced stress changes in the immediate roof are less likely if the pillars contain weak bedding planes.
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12/1/2003 - Conference papersPillar recovery has been associated with nearly one third of roof fall fatalities in underground coal mines during the past decade. This paper discusses design methods and technologies that have been transferred and implemented in mining.
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Content source: National Institute for Occupational Safety and Health, Mining Program