A Preliminary Insight into the Water Retention Response of Sand-Silt Mixtures of Stava Tailings

This research provides the main outcomes of an experimental investigation into the water retention behaviour of unsaturated tailing wastes collected after the failure of the Stava tailing dams. The water retention response of Stava tailings is studied by carrying out tests which apply different techniques where the water content was measured and the suction was imposed, and tests where the water content was imposed, and the suction was measured. The dependency of the Water Retention Curve (WRC) on the grain size distribution, and on the initial void ratio/density was investigated to account the in-situ heterogeneity of tailing wastes. As for standard soils, looser tailing specimens showed a lower water retention capability than that given in the denser ones. Similarly, the reduction of the fine content showed to decrease in the water retention capability of tailings. A microstructural interpretation in terms of the cumulative value of pore size density (PSD) is also provided. The in-depth knowledge of the hydro-mechanical response of the soils proposed by the current research finds its practical application as a fundamental tool to reliably assess the stability of the tailing storage facilities which the high rate of recent collapses poses unacceptable fatalities with environmental and economic damages.