The JELLYFISh Project: Medusa SDMT testing at the NGTS Geo-Test sites, Norway

Abstract

This paper presents an overview of the experimental activity and the main results obtained as part of the Transnational Access project – JELLYFISh funded by H2020-GEOLAB. The project is based on an extensive in-situ testing campaign with the Medusa SDMT, the newest fully automated version of the seismic dilatometer (SDMT). The campaign was carried out in June 2022 in different soil types at four well-known benchmark test sites in Norway: Halden (silt), Onsøy (soft clay), Tiller-Flotten (quick clay), and Øysand (sand). These benchmark sites, largely documented in previous research, are part of the Geo-Test Sites (NGTS) research infrastructure managed by the Norwegian Geotechnical Institute. The paper includes: (i) highlights of the JELLYFISh project, (ii) a brief description of the Medusa SDMT main features, (iii) a summary of the field testing program at the four sites, (iv) a comparison of the results provided by Medusa SDMT using alternative test procedures and by traditional (pneumatic) SDMT and (v) conclusions. The results of the project highlight that, due to improved accuracy of pressure measurements and controlled pressurization rate, the Medusa SDMT has the potential for providing significant advancement in soil characterization compared to the traditional SDMT technology. These capabilities are particularly useful when investigating soft clays (e.g., Onsøy) in which the measured pressures are typically very small, intermediate soils (e.g., Halden) in which non-standard test procedures using variable penetration/pressurization rates may be easily implemented, or sensitive clays (e.g., Tiller-Flotten) in which alternative test procedures may provide guidance for distinguishing quick and non-quick clays.

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