Water retention response of unsaturated Stava tailings

Tailing dams are geotechnical structures with a pronounced surface interaction with the atmosphere which leads to a large portion of material in unsaturated conditions. Due to the hydro - mechanical coupling, an accurate prediction of the hydraulic behaviour within the unsaturated layers has a significant effect on the mechanical behaviour, particularly in terms of the stability of tailing dams both during mining activities and after operations cease. This research provides the results of an investigation on the hydraulic behaviour of tailings collected from the Stava basins. The hydraulic response was studied by means of water retention tests where the suction was imposed and the water content was monitored, and tests where the water content was imposed and the suction was measured with psychrometer. The dependency of the water retention relationship on the particle sorting, the preparation technique and on the initial void ratio was studied to account for the in-situ heterogeneity of tailings. Looser specimens showed a lower water retention behaviour than that denser specimens. Similarly, the decrease of the fine content was demonstrated to reduce the water retention capability. Slurry Stava tailings reveal higher retention capability than the statically compacted samples, thus confirming the importance of the preparation technique in determining their hydro - mechanical response as previously demonstrated for standard soils.