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Cemented classified tailings sands are used worldwide as backfill in large underground mining operations. During the past decade, research has resulted in substantial reductions in backfill cement content. As the cement content of statically stable backfills is reduced, however, a concern arises with regard to dynamic stability under blast or earthquake loadings. The centrifuge model work reported in this paper represents an initial attempt to evaluate the effect of the lateral impact loadings caused by ring blasting on the stability of an exposed face of cemented classified tailings.
Centrifuge models, 300mm in height and having an in-flight static stability safety factor of about 1.3 under 100 gravities, were subjected to lateral impact loadings, impinging on the exposed vertical face to simulate the effect of ring blasting of an adjacent pillar. Cracking and face failures were induced in several of the models by the impact loadings but the model results generally indicate that cemented backfills having a static safety factor of 1.3 or greater are not likely to be damaged by controlled blasting operations. The potential effects of earthquake loadings on cemented mine backfills are also briefly discussed in the paper. Accelerometers and dynamic stress transducers were embedded in the backfill models. The design, fabrication and calibration of the dynamic stress transducers are referenced in the paper. The paper includes similitude analysis indicating that accelerated modelling is necessary to examine prototype dynamic behaviour.
centrifuge model, blast damage, mine backfill
Professor, Queen's University, Kingston,
Geotechnical Dept. Head, BCI, Lakeland, Fl