Long-Term Stress-Strain Behavior of a Seafloor Soil
Final rept. Jul 1974-Jun 1975
CIVIL ENGINEERING LAB (NAVY) PORT HUENEME CA
Pagination or Media Count:
A calcareous deep-sea soil from the central Caribbean was subjected to a series of consolidation, triaxial shear, and triaxial shear creep tests to determine its response to loadings of engineering interest. The soil, classified as an inorganic silt, tended to densify during transport. Compression index C sub c is 0.80 empirical terrestrial engineering correlations between C sub c and other easily and rapidly measured index parameters may be in error by 30. No significant crushing of the hollow foraminifera tests shells comprising the coarse-size fraction of the sediment was noted in the consolidation tests up to stresses of 1,530 kPa 32,000 psf. This coarse-size fraction does, however, undergo significant crushing if material finer than 0.43 mm is removed, suggesting that the fine-sized fraction distributes loads on the coarse-sized test shell surfaces. Grain crushing may be partly responsible for the curved failure envelope developed from the triaxial shear tests. For specimens consolidated up to 30 kPa 4 psi the angle of internal friction for the calcareous ooze is 0.60 rad 34 deg specimens consolidated to greater pressures describe a flattening of the failure envelope to 0.49 rad 28 deg. Triaxial shear creep tests indicate that creep failure in this soil is not a significant engineering problem. The data suggest that material consolidated to higher stress levels than those used here 100 kPa and then shear loaded undrained will develop failure strains at stress levels less than 80 of short- term failure stress levels.
- Physical and Dynamic Oceanography
- Soil Mechanics