Centrifuge Tests on Comixing of Mine Tailings and Waste Rock

A series of centrifuge tests were conducted to examine self-weight consolidation, dynamic response, liquefaction potential, and slope stability of mine tailings alone and in mixtures with waste rock. Mixture ratio of waste rock to tailings by dry mass varied around the region of a rock skeleton just-filled with liquefiable mine tailings (roughly 2.3∶1 in this case). The performance of three mixtures was compared to that of tailings in terms of pore pressure dissipation, shear wave velocity, soil acceleration, lateral displacement, pore pressure buildup, liquefied depth, settlement, and slope stability. Comixing proved to be a promising alternative to conventional separate disposal. Consolidation time and settlement were reduced significantly, and shear wave velocity increased with increasing rock content. The improvement in dynamic response was not pronounced when the tailings proportion was larger than required to fill the rock skeleton but became very apparent when that ratio was reached or surpassed.