The nonlinear dynamic properties of a fibrous peaty organic soil beneath a levee in the Sacramento-San Joaquin Delta in California are described. Thin-walled tube samples were obtained from 4 locations between the levee crest and free field such that the in situ vertical effective stresses ranged from about 12 kPa in the free field to about 135 kPa under the levee crest. Peaty organic soil was very soft and highly compressible in the free field with initial water content (w/c) of 236-588% and shear wave velocities of typically 22-27 m/s, and moderately firm under the levee crest with w/c of 152-240% and shear wave velocities of typically 88-129 m/s. Stress-strain measurements in a cyclic triaxial device showed the normalized secant shear modulus (G/G-sub-max) and equivalent damping ratio vs. cyclic shear strain amplitude relations were dependent on the consolidation stress. Tests involving prior overstraining followed by reconsolidation showed that the effects of sample disturbance were likely small. Stress history, creep, and loading frequency effects were also examined.


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  • Accession Number: 00964505
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Oct 8 2003 12:00AM