Influence of net stress on the soil-water retention curves of a natural pyroclastic soil

This paper shows the preliminary results of a research aimed at investigating the role played by the vertical net stress on the trend of soil-water retention curves of a natural pyroclastic (ashy) soil. To this aim, laboratory tests are carried out (under zero load and constant load conditions) by using equipments able to cover matric suction values ranging from 2 to 800 kPa along drying paths. The measured data are fitted with bimodal parametric functions useful to retrieve air-entry values and percentages of the total porosities pertaining to two porosity systems of the investigated soil.