Behavior of Cemented Paste Backfill in Two Mine Stopes: Measurements and Modeling
Publication: Journal of Geotechnical and Geoenvironmental Engineering
Volume 137, Issue 2
Abstract
Over the past decade there has been increasing use of “paste” for backfilling of mined-out voids (“stopes”) in underground mines. Paste backfill is generated from full stream tailings and is almost always placed underground with cement. This paper presents field measurements and back analysis of two different cemented paste backfill (CPB) cases. Using the collected data and subsequent back analysis, the writers show that these two cases demonstrate considerably different consolidation behaviors, which in turn influence critical design and management aspects such as applied barricade stresses and choice of an appropriate curing technique for laboratory control specimens. The paper presents pore pressure and total stress monitoring data gathered from two different CPBs during the deposition process. Both filling cases are modeled using Minefill-2D, which is a finite-element (FE) model capable of fully coupling the time-dependent processes of fill accretion, consolidation, cement hydration, and stress arching. Input parameters for the model are obtained from independent laboratory tests. Comparison between measured values and those calculated based on laboratory measurements verifies that, in general, the model provides a good representation of the process. However, there are some significant difficulties relating to modeling a three-dimensional stope with a two-dimensional plane-strain FE program, and some ways of accounting for these difficulties are explored. The model is then used to extrapolate the measured results to investigate the influence of varying filling rate, cement content, and number of drawpoints on critical design aspects.
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Acknowledgments
This work was carried out as part of the Australian Centre for Geomechanics (ACG) research project “An effective stress approach to mine backfill.” We wish to thank the sponsors of this project, Panoramic Resources, Barrick, and BHP Billiton, for their support of this research. Financial support for the first writer’s Ph.D. work at UWA was provided by the UWA Gledden Postgraduate Scholarships Foundation, the Shaw Memorial Postgraduate Scholarship Foundation, and the Minerals and Energy Research Institute of Western Australia (MERIWA), and we wish to acknowledge their financial contribution to this research.
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Information
Published In
Journal of Geotechnical and Geoenvironmental Engineering
Volume 137 • Issue 2 • February 2011
Pages: 171 - 182
Copyright
© 2011 ASCE.
History
Received: Mar 10, 2009
Accepted: Jul 21, 2010
Published online: Jul 22, 2010
Published in print: Feb 2011
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