On The Compression Behaviour of Unsaturated Silty Tailings: An Experimental Investigation

Abstract

A detailed characterization of tailings under unsaturated conditions is essential to reproduce their stressstrain response and represents a key tool for assessing reliable stability analysis of tailing dams both during the design phase, the mining activities, and after operations cease. Given these aspects, this research shows the main results of an experimental campaign carried out on quarzitic tailings to analyse their hydro-mechanical behaviour under unsaturated conditions. The investigation consists of oedometer compression tests on the silty fraction of Stava tailings under constant water content conditions. The effects of the matric suction and sample preparation technique on the 1d-Normal Compression Line (1d-NCL), the compressibility, and the occurrence of a transitional behaviour are studied, with the suction level evaluated based on the water retention tests (WRC). The experimental results are compared with those obtained under saturated conditions and with literature data dealing with fine soils in an unsaturated state. The Basic Barcelona Model (BBM) was proved to successfully describe the dependency of the soil compressibility, the pre-consolidation stress, and the recompression also of tailing materials on their suction level.