This study was undertaken to investigate the implication of geoacoustic behaviors in the shallow marine sediments associated with the changes in geotechnical index properties. Two piston cores (270 cm and 400 cm in core length) used in this study were recovered from stations 1 and 2, the western continental margin, the East Sea. Scanning electron microscopy (SEM) was employed to illustrate the effects of microstructure on shear properties. The direct SEM observation of sediment fabrics is inevitable to understand the correlation of the changes in geoacoustic properties to the sediment structure. The consolidation of sediments by overburden stress resulting in the clay fabric alteration appears to play an important role in changing shear properties. Water contents and porosity of sediments gradually decreases with increasing depth, whereas wet bulk density shows a reverse trend. It is interesting to note that shear wave velocities increase rapidly from 8 to 20 m/s while compressional wave velocities significantly fluctuate, ranging from 1450 to 1550 m/s with depth. The fabric changes in sediment with increasing depth for example, uniform grain size and well oriented clay fabrics may cause the shear strength increase from 1 to 12 kPa. Shear wave velocity is, therefore, shown to be very sensitive to the changes in undrained strength for unconsolidated marine sediments. This correlation allows an in-situ estimation of shear stress in the subsurface from shear wave velocity data.
Bibliographical noteFunding Information:
We thank three anonymous reviewers for their critical comments. This work was supported by Korea Research Foundation Grant (KRF-2003-050-C00017). This work was partly funded by the Korea Institute of Geoscience and Mineral Resources (KIGAM). Samples for this study were provided by Dr. Joan M. Gardner at Naval Research Laboratory, Washington D.C. USA. This research was also supported by grant (No. R01-2002-000-00369-0) from the Basic Research Program of the Korea Science & Engineering Foundation. BKK appreciates the support from the second stage of BK 21 in 2006.
All Science Journal Classification (ASJC) codes
- Geotechnical Engineering and Engineering Geology
- Ocean Engineering