Record Details
Shear wave attenuation in unconsolidated laboratory sediments
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Shear wave attenuation in unconsolidated laboratory sediments |
| Names |
Brunson, Burlie A.
(creator) Johnson, Richard K. (advisor) |
| Date Issued | 1983-06-23 (iso8601) |
| Note | Graduation date: 1984 |
| Abstract | Shear wave attenuation measurements were made using ceramic bimorph transducers to excite transverse vibrations in a cylindrical column of unconsolidated sediment. Three different water-saturated sediments were used in an attempt to determine the effects of grain shape and sorting on the frequency dependence of attenuation. The mean grain size of the sediments was held constant while the grain shape and size distributions were varied. The sediment assemblages used in the attenuation measurements included a moderately-sorted angular quartz sand, a well-sorted angular quartz sand, and well-sorted spherical glass beads. The moderately-sorted sand showed the greatest attenuation over the measurement frequency range of 1 to 20 kHz. The well-sorted sand and the glass beads showed generally lower attenuation with the beads being the least lossy propagation medium. All three sediments showed evidence of viscous attenuation due to fluid-to-grain relative motion. This mechanism leads to a non-linear relationship between attenuation and frequency. Sediment physical properties were measured for use as inputs to a theoretical attenuation model based on the Biot theory of propagation of waves in porous media. The model allowed attenuation versus frequency predictions to be made for each of the three sediment assemblages. The resultant comparisons between the measured and predicted attenuations demonstrated the importance of using measured model inputs obtained under controlled laboratory conditions when theoretical model capabilities are being evaluated. The model comparison shed significant light on the ability of this particular model to predict shear wave attenuation in non-ideal sediments. |
| Genre | Thesis/Dissertation |
| Topic | Shear waves |
| Identifier | http://hdl.handle.net/1957/26762 |
