Shear wave velocity as function of cone penetration test measurements in sand and silt mixtures

A database of research-quality piezocone test (CPTU) results and shear wave velocity Vs measurements, as- 23 sembled in the context of an ambitious research project carried out at the Treporti test site (Venice, Italy), 24 has been interpreted in order to study the seismic response of the predominantly silty sediments forming 25 the Venetian lagoon basin as well as to explore potential correlations for such intermediate soils. The 26 experience gained so far with the Treporti database and other field data collected in the lagoon area has 27 shown that the mechanical behavior of Venetian soils cannot be easily interpreted using the existing and 28 well-established CPTU-based approaches, hence the interest in examining whether or not the seismic re- 29 sponse of these sediments, expressed in terms of shear wave velocity, follows the framework published for 30 other soils. The applicability to the available data of a number of existing correlations, originally developed 31 either for sands or fine sediments, has been first investigated and updated relationships have been then sug- 32 gested. Furthermore, the small-strain stiffness calculated from Vs measurements has been compared with the 33 field stiffness derived from the observed performance of a full-scale test embankment built in the Treporti 34 site, so as to verify common design assumptions. The verification and calibration of existing approaches are 35 likely to constitute a useful contribution to the practice of geotechnics not only in the Venetian lagoon 36 area, but also in the silty deposits usually present in the surrounding alluvial plain and other similar deposi- 37 tional environments, allowing rapid estimates of seismic soil classification as well as small-strain stiffness 38 properties for preliminary design or at sites where only cone penetration data are available.