Analysis and interpretation of piezocone data from the Treporti test site for the evaluation of compressibility characteristics of silty soils.

The 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 rather ambitious 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 comprehensive monitoring system of surface settlements, pore water 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 in-situ testing technique, especially for stratigraphic profiling of the predominantly silty subsoil of the Venetian lagoon, but at the same time reveals some evident limitations of widely used empirical correlations for the relevant soil characterization, with special reference to compressibility and consolidation properties of such intermediate sediments. Indeed, potentially dilative behaviour of these soils, as well as partial drainage effects during cone penetration, must be taken in careful consideration in order to derive reliable soil parameters from in-situ measurements.