Geotechnical Engineering Characterization of Hydraulically Piston-Cored Deep Ocean Sediments

Abstract

The hydraulic piston coring device (HPC-15) allows recovery of deep ocean sediments with minimal disturbance. The device was used during Leg 72 of the Deep Sea Drilling Project (DSDP) aboard the Glomar Challenger. Core samples were recovered from bore holes in the Rio Grande Rise in the southwest Atlantic Ocean. Relatively undisturbed sediment cores were obtained from Holes 515A, 516, 517, and 518. The results of shipboard physical property measurements and on-shore geotechnical laboratory tests on these cores are presented in this chapter.A limited number of 0.3 m cores were obtained and used in a series of geotechnical tests, including one-dimensional consolidation, direct shear, Atterburg limit, particle size analysis, and specific gravity tests. Throughout the testing program, attention was focused on assessment of sample disturbance associated with the HPC-15 coring device.The HPC-15 device limits sample disturbance reasonably well in terrigenous muds (clays). However, sample disturbance associated with coring calcareous sediments (nannofossil-foraminifer oozes) is severe. The noncohesive, granular behavior of the calcareous sediments is vulnerable to severe disturbance, because of the design of the sampling head on the device at the time of Leg 72.A number of modifications to the sampling head design are recommended and discussed in this chapter. The modifications will improve sample quality for testing purposes and provide longer unbroken core samples by reducing friction between the sediment column and the sampling tool.

Coring disturbances in IODP piston cores with implications for offshore record of volcanic events and the Missoula megafloods

“…Advanced Piston Coring (APC) under the IODP was developed through improvements to earlier versions of piston coring, first tested during the Swedish Deep Sea Expedition [e.g., Kullenberg , ; Weaver and Schultheiss , ]. New technology in the early 1980s provided the Hydraulic Piston Corer (HPC), which was attached to the drilling equipment of the D/V Glomar Challenger [ Walton et al ., ; Ruddiman et al ., ] and applied by pumping pressure to the drill pipe rather than operating as a stand‐alone piston corer. Currently, the R/V JOIDES Resolution drilling vessel uses an improved version of the HPC, the Advanced Piston Corer (APC) [ Huey , ].…”

“…Basal flow‐in units may be underlain by units that experienced mild to strong sediment liquefaction and mixing. Unconsolidated, massive, soupy, ungraded to complexly graded, sandy to pebbly units that are not underlain by cohesive mud (which would act as a seal between the cored sediments and the open‐ended cutting shoe) are prone to contain a significant amount of basal flow‐in sediment [e.g., Stow and Aksu , ; Walton et al ., ; Blomqvist , ]. The original stratigraphy in sandy and pebbly beds can be preserved where sandwiched between undeformed beds of cohesive mud.…”

Physical Properties of Carbonate Turbidite Sequences Surrounding the Bahamas—Implications for Slope Stability and Fluid Movements

“…Although this technique was designed to produce minimal artificial compaction, core disturbances, especially dewatering, have been reported from unconsolidated calcareous sediments (Walton et al, 1983). Therefore, only well-preserved turbidites with a minimum thickness of 0.1 m were used in this study to ensure accurate physical-property data.…”

Physical Properties and Consolidation of the Calcareous Sediments of Broken and Ninetyeast Ridges

“…An important consideration in interpreting these tests is the disturbance the sample has undergone during coring, retrieval, and handling. Typically, hydraulic piston coring may induce disturbance to loose, unconsolidated calcareous sediments (Walton et al, 1983). A measure of this disturbance may be indicated from the shape of void ratio vs. applied stress curves, or e-logp curves.…”