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Conference Paper

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This conference paper was originally published as Oraee, K, Hosseini, N & Gholinejad, M, Estimation of Coal Pillar Strength by Finite Difference Model, in Aziz, N (ed), Coal 2009: Coal Operators' Conference, University of Wollongong & the Australasian Institute of Mining and Metallurgy, 2009, 54-61.


Longwall mining is now predominately used in coal mines where somewhat difficult conditions exist. As in the case of all other underground mining methods, pillars are integral part of modern mine design. The process of pillar design in longwall mining entails the selection of a safety factor, which is done by estimating the magnitude of the load applied on the pillar and the load bearing capacity of such pillars. Finite difference modelling principles have been applied to a typical coal pillar design. The pillar strength is then estimated with various width/height ratios. These results have been compared with the results obtained from the conventional pillar design methods. The effect of roof and floor quality on the strength of the typical pillar has also been evaluated in the same manner. Although the finite difference method is not always the perfect method for such estimation, nevertheless, the results clearly demonstrate that it produces more acceptable design than the conventional method, especially under undesirable conditions regarding the interface between pillars, roof and floor. An additional advantage of such method is its capability of being applied in situations where complex parameters prevail.

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