Assessment of the Self-Compaction Effect in Filtered Tailings Disposal under Unsaturated Condition

Abstract

Filtered tailing is a relatively-environmentally friendly technique due to the recovery of water during the process of dehydration. This technique was recently developed and therefore there are few studies available compared to research on conventional tailings. This work focuses on the behaviour of a filtered copper tailing under an unsaturated condition, studying the effect of self-compaction by self-weight which is triggered by the deposition process through 1D consolidation tests. In addition, the impact of confinement on the stiffness and shear strength was studied by means of unsaturated drained triaxial tests. The initial matric suction was determined based on soil-water characteristic curves for two initially loose dry densities and the water content at which the material leaves the dehydration process. The unsaturated consolidation tests showed that for vertical stresses above 100 kPa and with ratios between the applied matric suction and air entry value lower than twelve, the material approaches saturated condition, reaching up to 95% degree of saturation. On the other hand, for the unsaturated drained triaxial tests, the effect of the matric suction generates increases in the shear strength and the stiffness of the material up to 200% and 600%, respectively. However, the increase tends to disappear as confinement increases.