Preliminary Evaluation of the Effects of the Unsaturated Conditions on the Pre-Shearing State of Stress of Quarzitic Tailings

This paper deals with the laboratory investigation of the compressibility of a silty soil, representative of tailing wastes, under unsaturated conditions.The experimental activity consisted of a series of conventional oedometer tests to analyse the stress-strain response at variable suction levels, and a series of water retention tests to determine the water retention curves to be later used for the theoretical interpretation, which was conducted according to the Barcelona Basic Model (BBM).The dependency of the soil compressibility, 1d-Normal Compression Line (1d-NCL), pre-consolidation stress and recompression index on the matric suction is preliminarily analysed.Both the compression and recompression indexes of Stava tailings were observed to decrease with suction.The experimental evidence also showed an increase of the pre-consolidation stress with suction, and the results find a good agreement with literature data obtained on more standard soils..