Analytical and Experimental Study of Cemented Backfill and Pillar Interactions
Publication: International Journal of Geomechanics
Volume 19, Issue 8
Abstract
Massive voids form in underground mines due to the continuous removal of valuable minerals. Backfill and pillars are commonly built into the voids to provide both local and regional support. The backfill material cannot rigidly support the upper load and acts as a secondary support system to the pillars. Confinement effect effectively enhances the strength of the pillar; however, the lateral stress mobilized within the fill is contingent upon deformation of the roof and pillars, which act as a passive support. Without large-scale volumetric compression, the backfill has no effect on the prepeak stage of the pillar. In this case, the friction resistance of the interface between the pillar and backfill plays a key role in increasing the load capacity of the support system. This paper presents an analytical solution based on the load transfer of friction force in the interface, which involves the shear behavior of the interface, the mechanical properties of the pillar, and the pillar dimensions. Experimental results showed that the bearing capacity of the support system was strongly dependent on the interface shear parameters, lateral stress, and fill ratio. Comparisons were made between the proposed solution and experimental results. The results may represent a workable understanding of the interaction mechanism between backfill and pillars and assist in the design and optimization of underground mine support systems.
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Acknowledgments
This work is funded by the National Key Research and Development Program of China (Grant 2016YFC0801607), National Science Foundation of China (Grants 51525402, 51874069, and 51761135102), and the Fundamental Research Funds for the Central Universities of China (Grants N180115009 and N170106003). These supports are gratefully acknowledged.
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Published In
International Journal of Geomechanics
Volume 19 • Issue 8 • August 2019
Copyright
© 2019 American Society of Civil Engineers.
History
Received: May 17, 2018
Accepted: Jan 3, 2019
Published online: May 16, 2019
Published in print: Aug 1, 2019
Discussion open until: Oct 16, 2019
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