First Tests of Penfeld: a New Seabed Penetrometer

摘要

IFREMER carries on the development of deep sea geotechnical tools. After the Geotechnical Module which was able to assess soil properties until 2 m below seabed, IFREMER has developed and tested a new seabed penetrometer which is able to perform in-situ geotechnical measurements in deep sea with a depth of investigation of 30 metres below the sea bottom. The penetrometer is lifted over the seabed and stands during the penetration and the retrieval of the rod. To ensure compact dimensions of the tool, the rod is a whole and is bent following a diameter of 2.15 m and straightened under the technique of “coiled tubing”.After trials in testing pool and on land, the Penfeld penetrometer was tested twice in the Mediterranean Sea, 25 miles south of Nice on a site where cores were previously sampled by Kullenberg corer. With the recovered cores, it is possible to identify the mechanical and lithological properties of the soil where cohesive and non-cohesive sediments interbed one another. Comparisons between laboratory results and the values obtained using the cone penetrometer show that Penfeld make possible not only drawing conclusions regarding the mechanical properties of the soil but also defining the soil type.