GEOLAB - Transnational Access project JELLYFISh - Field testing of Medusa DMT

The project JELLYFISh (A Just-released innovativE in-situ soiL testing technoLogY (Medusa DMT/SDMT) For enhancing the resilience of the critical InfraStructure in Europe) aims to contribute to the advancement of knowledge on geotechnical characterization of soil deposits commonly encountered in risk-sensitive areas (intermediate soils, soft clays, quick clays, loose sands), often associated to multiple geo-hazards that may negatively interact with CI networks. Improvements in geotechnical approaches to analysis and mitigation of such hazards, in order to increase the resilience of the CI, rely significantly on enhanced characterization of soil behaviour.

The methodology employed for this purpose is the innovative Medusa (S)DMT in-situ soil testing technology. The research project is based on an extensive experimental in-situ testing program with Medusa (S)DMT in different soil types at benchmark Geo-Test Sites (NGTS), part of the research infrastructure managed by the NGI. A comprehensive high-quality soil database, including data from field and laboratory tests, published articles and reports, is available from NGI. The sites (target soil types) that were recognized of specific interest for this project are Halden (silt), Onsøy (soft clay), Tiller-Flotten (quick clay), and Øysand (sand).

The project benefits from the collaboration of users from industry and academia, making use of the access to the GEOLAB facility to test and implement new technology solutions. The relevant Technology Readiness Level (TRL) of the project is in the group (TRL4-7), pertaining to technology development of solutions to enhance the resilience of the CI.

The main objectives of the project and their significance in terms of innovation / advancement of knowledge are:

Innovative approach for characterizing the in-situ behaviour of intermediate soils by Medusa DMT tests at variable pressurization/penetration rates, in combination with available data from variable-rate CPTU tests.

Advancement in soil property characterization of soft clay deposits by innovative in-situ testing procedures (e.g., in-situ horizontal stress / coefficient of earth pressure at rest K0 from continuous measurement of total horizontal pressure during Medusa DMT penetration).

Novel approach for mapping quick clay layers by innovative in-situ testing procedures (continuous measurement of total horizontal pressure during Medusa DMT penetration).

Improvement of DMT interpretation in sand, including the investigation of the effect of fines content and partial drainage (to be introduced into DMT-based simplified methods for liquefaction assessment).