Softening Effects on Bearing Capacity of Mine Floors
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 125, Issue 12
Abstract
A major cause for massive collapse of coal mines in the Illinois Basin is the softening of mine floors. Certain materials present in mine floors soften after coal extraction resulting in bearing capacity failure of coal pillars. The softening mechanisms considered in this study were (1) slaking/swelling due to moisture exposure; and (2) creep or strain softening due to sustained loads. The effect of floor slaking or swelling on floor stability can be fairly dramatic. In some cases, shortly after pooling of water on the mine floor, collapse occurs resulting in surface subsidence. In other cases, the time factor is greater. The effect of softening on the ultimate bearing capacity of the mine floor was assessed by modeling representative conditions using FEM and elastoplastic elements. In the models, the properties of softened mine floors were determined from results from subsurface exploration work in floor areas that were stable and others that had failed. The zone of softening was evaluated by stress-field analysis.
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Information & Authors
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Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 125 • Issue 12 • December 1999
Pages: 1078 - 1089
History
Received: Jun 1, 1998
Published online: Dec 1, 1999
Published in print: Dec 1999
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