Hydraulic Behaviour of Unsaturated Pyroclastic Soil Observed at Different Scales

Proper soil water retention curves (SWRCs) and hydraulic conductivity functions (HCFs) are necessary for a fair analysis of groundwater flow in unsaturated slopes. In principle SWRC is hysteretic; as a consequence, laboratory characterization may not be sufficient to determine the scanning curve and the hydraulic parameters operating in situ. In this paper some results obtained by tests at different scales (testing on laboratory specimens and physical prototype and measuring in an experimental field) are presented in order to explore the hydraulic behaviour of pyroclastic soils. As regards HCF, in the paper the comparison between the hydraulic conductivity functions obtained from inverse analysis of evaporation lab tests, and the conductivity values estimated on the basis of both in situ measurements and results of tests on the aforementioned physical model is proposed. From these results, the physical prototype size (medium scale) seems to be acceptable for determinations of both SWRC and HCF.