Analysis and interpretation of piezocone data on the silty soils of the Venetian lagoon (Treporti test site)

This paper reports the main results of an extensive piezocone testing campaign performed over the last years at the Treporti test site (Venice, Italy) within a long-lasting and comprehensive research project aimed at developing a reliable geotechnical model of the heterogeneous and highly stratified Venetian lagoon basin. The project included the construction of a full-scale vertical-walled cylindrical test bank, together with a detailed monitoring system of surface settlements, porewater pressures, subsoil strains, and stresses beneath the loaded area. The analysis of the large amount of data thus available, referring to different phases of the loading history, confirms the great potential of piezocone as an in situ testing technique, especially for stratigraphic profiling of the predominantly silty subsoil of the Venetian lagoon, but at the same time reveals some limitations of widely used empirical correlations for the relevant soil characterization, with special reference to compressibility and consolidation properties of such intermediate sediments. Indeed, partial drainage effects during cone penetration, as well as potentially dilative behaviour of these soils, should be taken into careful consideration to derive reliable soil parameters from in situ measurements. More suitable site-specific correlations have been introduced, according to the recent findings on piezocone data interpretation.