GEOTECHNICAL CHARACTERIZATION OF SURFICIAL HIGH-POROSITY SEDIMENTS INECKERNFORDE BAY

Geotechnical studies of high-porosity, fine-grained sediments from Eck ernforde Bay, part of the Coastal Benthic Boundary Layer program, incl uded coring, subsampling, and on-board testing during three field expe riments, and a laboratory testing program to determine the mechanical properties of the seabed. The sediments consist of high-porosity (86-9 4%), organic-rich (10-20%) silty clays with varying amounts of methane gas. The surface 5-10 cm are characterized by unusually high water co ntents (400-600%), very low shear strengths (<1 kPa), and pronounced s hear thinning behavior. Below that depth sediments are somewhat more c ompetent, exhibiting water contents of 250-300% and higher strengths ( >1 kPa).