Eight 10-cm-long whole-round samples, earmarked for consolidation testing, were subsampled from cores during Leg 164. They were preserved in the original liner, capped, completely covered in wax, and subsequently stored in a refrigerator at a temperature of ~4°C. Two different studies utilized the samples. A 3-cm-long whole-round subsample was removed to check the influence of drying temperature on water content and to perform mineralogic and grain-size analyses (Winters, Chap. 41, this volume). The remaining material was used for index properties (Atterberg limits), vane shear and pocket-penetrometer strength tests, and constant-rate-of-strain consolidation tests. The sediment was described at sea as nannofossil- and diatom-bearing and nannofossil- and diatom-rich clay to claystone in Hole 995A (Shipboard Scientific Party, 1996). Shore-based grain-size analyses graded the sediment as clayey silt size (Winters, Chap. 41, this volume).
Index properties provide information on general engineering behavior. Water content, corrected for salinity, were determined according to American Society for Testing and Materials (ASTM, 1997a, 1997b) Standard D 2216-92, except that the drying temperature was 90°C rather than the specified 110°C to reduce mineralogical changes that can be produced at the higher temperature. Plastic limits were performed according to ASTM (1997a, 1997b) Standard D 4318-95a. However, the fall cone method was used to perform liquid limit tests according to procedures outlined in Head (1980) and Winters (1988).
The relative value of the natural water content in relation to the Atterberg limits (liquid limit, wL, and plastic limit, wP) indicates whether the remolded sediment behaves like a liquid, plastic, or semi-solid. That relationship is expressed by the liquidity index, IL = (wc-wP)/(wL-wP). A IL larger than 1.0 indicates that the natural water content is greater than the liquid limit and that the behavior of the sediment would approximate that of a liquid upon remolding. The plasticity index, IP = wL-wP, provides a quantification of the range of water content over which the material exhibits plastic behavior.
A laboratory
miniature-vane-shear apparatus and a pocket penetrometer, similar to those used
at sea during Leg 164, were also used for this study. The vane-shear test was
performed according to ASTM (1997a, 1997b) Standard D 4648 using a 12.7-mm high 
12.7-mm diameter vane at a rotation rate of about 90°/min. Torque was applied
through a spring system. The pocket penetrometer was quickly pushed into
fine-grained sediment so that drainage would not occur and the measured
unconfined compressive strength was converted to shear strength.
Back-pressured constant-rate-of-strain consolidation (CRSC) tests were performed using a unique triaxial test system called GHASTLI (Gas Hydrate And Sediment Test Laboratory Instrument; Booth et al., 1994; Winters et al., 1994) on 63.5-mm-diameter by 18.9-mm-high specimens, according to ASTM (1997a, 1997b) D 4186. This test system has a high loading capacity and was therefore well suited for performing tests on deep borehole sediment.
