Characterization of Seismoacoustic Properties of Marine Sediments
Abstract
Experimental findings are presented on fundamental seismoacoustic characteristics of unconsolidated sediments not explained by existing theories. Precision measurements of the compressional velocity "C(p)" in coarse water-saturated sand revealed that C(p) decreased by 14% as frequency increased from 80 to 880 kHz, while the Biot theory predicted an increase of < 1 %. Measured dispersion in saturated fine sand and glass beads had a similar trend. Data from Kings Bay Experiment by Chotiros (1995) were replotted indicating that C(p) decreased by 6% as frequency increased from 5 to 60 kHz. C(p) in drained sand and glass beads remained near the saturated value 1750m/s in contrast with the 85% decrease predicted by the low-frequency Biot-Gassman theory. Time-dependent stiffening was detected in drained sediments. Visualization of capillary mechanisms using seawater and glass microplates provided physical insight into grain to grain coupling and time-dependent properties. Unique features were observed on crystallization in confined geometry, solid-like behavior of confined seawater, cavitation, and shear coupling. Capillary experiments on gassy sediments showed that when air was injected in water-saturated sand, oblique 45 degrees fracture cracks formed in the sand as it became locally unsaturated. The cracks were perpendicular to each other originating from the air source location.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 2003
- Accession Number
- ADA417984
Entities
People
- Jacques R. Chamuel