Usefulness of Spade Cores for Geotechnical Studies and Some Results from the Northeast Pacific
The next best thing to in situ measurements of sediment engineering properties is probably data collected from cores taken with spade corers. Included in the discussion are the advantages and disadvantages of spade cores compared to conventional smalldiameter cores.
The “undisturbed” nature of spade cores is also illustrated. Changes in temperature or storage in water for periods up to 7.5 months do not significantly alter the shear strength of the sediment.
Despite popular beliefs, pelagic sediments are not homogeneous over extended distances. Significant differences in shear strength occur even within the horizontal confines of a single spade core. These differences are ascribed to bioturbation. Drastically different strength characteristics also occur over distances of a mile or less due to different depositional histories. Characteristics of deep-ocean sediments may prove to be as variable as shelf sediments.
KeywordsShear Strength Triaxial Shear Test Depositional History Manganese Nodule Gravity Drainage
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