Measurement of the complex dynamic rigidity of recent marine sediments.

Abstract

The dynamic rigidity of 17 samples of continental terrace clayey-silt sediments has been measured in the laboratory using a viscoelastometer in the frequency range of 7 to 60 kHz. The method involves the propagation of torsional waves on a rod and measuring the effects of shear loading imparted to the rod when imbedded in a sediment. Values of the real component of rigidity range from 1.6 X 10⁶ dynes/cm² to 2.1 X 10⁷ dynes/cm². Values of the imaginary component of rigidity range from 2.0 X 10⁵ dynes/cm² to 4.1 X 10⁷ dynes/cm². No clear-cut dependence of rigidity upon frequency is observed. Both real and imaginary components of rigidity are analyzed by plotting the data as a function of various other mass-physical properties, including: density, porosity, compressional wave speed, sand-silt-clay percentages, vane shear strength, and the product of density and sound speed squared. These analyses substantiate research done by other workers indicating that both real and imaginary components of rigidity exhibit trends with some of the mass-physical properties.