Potential of the Medusa DMT for offshore geotechnical investigation

The Medusa DMT is the newest fully automated version of the flat dilatometer popularly used in soil investigation. The Medusa DMT can operate autonomously without the traditional control unit, the gas tank and the pneumatic cable which is an advantage for offshore testing. The seismic version (Medusa SDMT) incorporates additional sensors for measuring the shear wave velocity. Due to improved accuracy in pressure measurements and controlled pressurization rate, the Medusa DMT is useful for testing soils frequently encountered in coastal and nearshore/offshore environments. This paper presents early findings obtained from field tests carried out in Norway at two benchmark Geo-Test Sites, Onsøy (soft clay) and Halden (silt), managed by the Norwegian Geotechnical Institute. The soils at these sites, though onshore, have marine origins and resemble the offshore soil conditions at several oil/gas fields in the North Sea. The findings shed light on the potential use of the Medusa DMT for offshore investigation.