In-Situ Vane Shear Testing at Sea

In-situ vane shear testing to measure undrained shear strength in the offshore environment has experienced increased use and significant equipment improvements over the last decade. These changes arose from (1) the offshore petroleum industry's need to improve the quality of foundation site investigations for their structures, (2) technological advancements in mechanical and electrical systems, and (3) recognition by the geotechnical profession of the benefits of acquiring vane shear testing data for better interpretation of cohesive soil strength properties. This paper provides insight into the current international practice of in-situ vane shear testing by presenting results of a questionnaire to international experts. The paper also describes the historical developments that led to the current state of practice. A review of field vane deployment and important operational details is presented along with an appraisal of the applications of vane shear testing for foundation design purposes. The paper also presents various case studies demonstrating how vane shear testing data proved beneficial for offshore foundation design. Finally, the paper summarizes the author's opinions relative to the current state of the art of offshore vane shear testing and includes comments on possible future developments and applications.