Triaxial strength experiments completed on specimens from Integrated Ocean Drilling
Program Expedition 308 Sites U1322 and U1324 document internal friction angles from
17° to 29° and normalized undrained shear strength from 0.21 to 0.36 at maximum shear.
Just prior to undrained shearing, lateral stress ratios for these triaxial specimens
range from 0.50 to 0.73. In general, internal friction angle and normalized undrained
shear strength decrease with increasing vertical consolidation stress. Lateral stress
ratio does not vary systematically with vertical consolidation stress. All 18 specimens
in this study were collected with the advanced piston corer (APC). Specimens from
Site U1322 were from 27.3–72.9 meters below seafloor (mbsf), and those from Site U1324
were from 89.1–304 mbsf. For each specimen we completed a Ko-consolidated undrained
triaxial test to provide data on the stress-strain behavior, undrained shear strength,
internal friction angle, and secant modulus. Undrained shearing for each specimen
was conducted at a vertical consolidation stress exceeding the hydrostatic vertical
effective stress for that specimen.