WIT Press

An Integrated Approach For The Design Of Stable Mine Backfill Sillmats


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E De Souza & A P Dirige


Sillmats are structural elements used to support backfill in large underground mining excavations. Failure of such support structures may be catastrophic and result in substantial economic losses. The traditional design of cemented sillmats has been based on experience and on analytical models derived from static equilibrium analysis. This approach offers inherent limitations and generally results in conservative designs and expensive mine support installations. This paper presents a novel integrated procedure in which centrifuge modeling techniques are combined with numerical and analytical models to provide accurate engineering structural designs of sillmats. 1 Introduction In order to maximize the recovery of ore in modem and highly productive mining methods, cemented backfill is normally placed in underground excavations to provide structural support. In order to save on costs, backfill of low cement content is used to fill the mined out stopes. This backfill mass is supported by a sillmat structure cast from cemented backfill of very high strength. Mining excavations progress under the sillmats, which must remain stable when exposed and subjected to mine induced stresses. The stability behavior of the sillmat elements must be carefully studied to provide very effective, safe and economic mining operations. Improper design of these support structures may result in fill mass failure, with consequent losses of production, ore dilution, and in safety problems.