ABSTRACT
D.J. DeGroot University of Massachusetts Amherst, Amherst, MA, USA
T. Lunne Norwegian Geotechnical Institute, Oslo, Norway
T.I. Tjelta Statoil, Norway
ABSTRACT: The paper presents recommendations for conducting site characterisation programs to determine the geotechnical properties of cohesive offshore sediments with the primary focus being on clays. The engineering behaviour of clays is complex and characterisation of their in situ properties is magnified by additional challenges presented by offshore environments. Site investigation programs are best conducted using well calibrated in situ tests and laboratory testing of high quality undisturbed samples. Results from these test programs should be coupled with geophysical data and collectively evaluated in the context of a regional geological framework. The paper reviews clay behaviour, describes the unique conditions of offshore environments, and lists key cohesive soil parameters required for infrastructure design and geohazards analysis. Best practice recommendations founded on these fundamentals are then presented including drilling methods, in situ testing and instrumentation, soil sampling, laboratory testing and evaluation of test data. The paper concludes with an assessment of present and future challenges.
