Sealion: A Snellius-II Expedition Automatic System for In Situ Geotechnical Testing in Water Depths of 6000 m

Abstract

Deliberations between the Dutch and the Indonesian governments led to the organization of the Snellius-II Expedition, which took place in 1984 and 1985 in Indonesian territories. The Netherlands Council of Oceanic Research (NRZ) is the Dutch coordinating agency. Cooperation between the Free University of Amsterdam and Fugro BV personnel led to the development of a Geotechnical Project, as part of the NRZ’s scientific programme, to be included on one of the geological cruises in the eastern Banda Sea. This region is the location of three active plate boundaries and offered a unique opportunity for geotechnical investigations. Previous studies in other active margin areas had showed the influence of tectonic forces on the consolidation (dewatering) of the sediments (Carson, 1977). Excess pore-water pressures were thought to play an important role in these processes (von Huene and Lee, 1982). To derive in situ information on pore pressures, and to provide in situ shear strength data for comparison with laboratory data obtained from piston cores, an automated piezocone probe system, called the Sealion, was conceived. This was part of the spin-off from the feasibility study for the Deep Ocean Research Apparatus (DORA) (Richards, 1985) and partly from other corporate research and development. The development and testing of the Sealion (Table 1) in late 1984 and early 1985 for the NRZ is the subject of this chapter.