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Jumbo Piston Coring

TDI-BI vessels are equipped with 12m 3-inch diameter piston cores and 30m 4" Jumbo Piston cores (JPC) that can be collected at depths in excess of 4,000m. The 3" piston corer is operated from the midships A-frame. The JPC utilizes a cantilevered deployment platform over the stern of the vessel with a rail and capture bucket assembly placed on the deck of the vessel directly beneath the stern A-frame. The JPC consists of a 4,000-lb weight stand, a 4" core barrel, a mechanical trigger, standard schedule 40 PVC liner, a cutting shoe, and a foil core catcher.

Jumbo Piston Coring Rig Layout and Operation

Subbottom Chirp profiles are first run to provide near surface structural information and precise water depth. The vessel maintains position at the location so the sampler impacts the prescribed position within the accepted radius of error (usually 60 ft).

Geotechnical ASTM standardized testing may be performed at one meter intervals and include Torvane and miniature vane tests. In addition, UU triaxial compression tests may be performed on sections with shear strengths greater than 15 kPa using a 3-in.-diameter plugged sample. Moisture contents are measured for all UU triaxial and miniature vane test specimens in addition to Unit weight determination.
A shipboard geotechnical log is prepared for each core that includes: Core identification number, Coordinates, Water depth, Core recovery, Digital color photographs, Detailed Lithology, and Geotechnical testing results.