Recent Developments in Soil Investigation by Medusa SDMT

The Medusa SDMT is the fully automated version of the seismic dilatometer (SDMT). An extensive in situ testing campaign with the Medusa SDMT was carried out in June 2022 in different soil types at four benchmark test sites in Norway, part of the Geo-Test Sites research infrastructure managed by the Norwegian Geotechnical Institute. The experimental campaign was conducted within the Transnational Access project – JELLYFISh funded by H2020-GEOLAB. This paper presents a preliminary assessment of significant results obtained by Medusa SDMT at the Onsøy test site (soft marine clay), compared to data obtained by traditional (pneumatic) SDMT in past investigations. Furthermore, the comparison is extended to a different benchmark test site in Italy, Fucino-Telespazio (soft lacustrine clay), where Medusa DMT data are available from past studies. Despite significant differences in origin, deposition environment and geological history of the two clay deposits, the profiles of parameters measured and interpreted from Medusa (S)DMT exhibit remarkable similarities. Simultaneous assessment of the soil parameters inferred by Medusa (S)DMT and by the traditional SDMT technology highlights a significant improvement in soil characterization in terms of both the quality and repeatability of the data.