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Mining Publication: The Evolution of Intelligent Coal Pillar Design: 1981-2006

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August 2006

Image of publication The Evolution of Intelligent Coal Pillar Design: 1981-2006

The first International Conference on Ground Control in Mining opened with the topic of pillar design. Two classic papers were presented, one by Bieniwski and the other by Wilson. Unfortunately, the two methods were so radically different from each other that it was nearly impossible to reconcile them. Adding to the confusion were the many other pillar strength formulas (such as the Salamon-Munro, the Holland-Gaddy, and the Obert-Duvall, just to name a few) that were also available. Little wonder that discussions of pillar design in those days often ended with anguished cries of "but which formula is the right one? The past 25 years have seen substantial progress in the science of coal pillar design. Indeed, one testament to the improvement is the relative scarcity of papers on the topic at recent Conferences. Two factors have been largely responsible for the progress that has been made. The first has been the collection of large data bases of actual case histories of pillar performance in a variety of settings, from shallow room-and-pillar mines through deep cover longwalls. These have made possible the development of empirical design procedures that are closely linked to real world experience. The second important factor is the development of sophisticated computer models that can accurately simulate pillar behavior and roof/pillar/floor interactions. Together, these two lines of research have led to a new understanding of pillar mechanics that identifies three modes of pillar failure: Sudden, massive collapse, accompanied by airblast, for slender pillars (width/height<4). squeezing,="" or="" slow,="" non-violent="" failure,="" for="" most="" room="" and="" pillar="" applications="" (410).="" it="" is="" particularly="" satisfying="" that="" the="" insights="" gained="" from="" numerical="" models="" broadly="" support="" those="" obtained="" from="" the="" empirical="" studies.="" while="" far="" less="" controversial="" than="" in="" the="" past,="" pillar="" design="" problems="" continue="" to="" arise.="" one="" recent="" example="" is="" pillar="" design="" for="" highwall="" mining.="" niosh="" has="" just="" released="" a="" software="" package,="" called="" armps-hwm,="" which="" employs="" a="" number="" of="" modern="" pillar="" design="" concepts.="" since="" highwall="" mining="" web="" pillars="" are="" long="" and="" slender,="" the="" greatest="" danger="" is="" that="" of="" a="" sudden="" collapse.="" armps-hwm="" suggests="" two="" possible="" prevention="" strategies,="" one="" which="" concentrates="" on="" the="" sf="" of="" the="" webs,="" and="" the="" other="" which="" creates="" a="" "pressure="" arch"="" using="" properly="" sized="" barrier="" pillars.="" the="" paper="" will="" close="" with="" a="" discussion="" of="" some="" current="" needs="" in="" coal="" pillar="" design,="" including:="" updating="" older="" empirical="" methods,="" such="" as="" alps,="" where="" changes="" in="" technology="" (new="" types="" of="" roof="" support,="" more="" demanding="" ventilation="" requirements,="" faster="" retreat="" rates)="" may="" have="" made="" some="" of="" the="" original="" case="" histories="" obsolete.="" methods="" for="" determining="" site-specific="" coal="" strengths,="" focusing="" on="" bedding="" plane="" strength="" and="" other="" factors="" that="" may="" effect="" confinement,="" as="" input="" for="" both="" empirical="" and="" numerical="" design.="" improved="" methods="" for="" evaluating="" coal="" pillar="" performance="" for="" environmental="" issues,="" such="" as="" surface="" subsidence="" and="" hydrologic="" impacts,="" which="" consider="" such="" factors="" as="" depth,="" w/h="" ratio,="" water="" immersion/drainage,="" and="" time="" dependent="" seam="">

Authors: C Mark

Conference PaperAugust - 2006

  • Adobe Acrobat - Portable Document Format (.PDF)

    0.64 MB

NIOSHTIC2 Number: 20030828

Proceedings of 25th International Conference on Ground Control in Mining, August 1-3, 2006, Morgantown, West Virginia. Peng SS, Mark C, Finfinger G, Tadolini S, Khair AW, Heasley K, Luo Y, eds., Morgantown, WV: West Virginia University, 2006 Aug; :325-334

 
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