The Effects of Microstructure on Shear Properties of Shallow Marine Sediments |
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| Authors: | Gil Y Kim Hong J Yoon Jin W Kim Dae C Kim Boo K Khim Seok Y Kim |
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| Institution: |
a Petroleum & Marine Resources Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), South Korea
b Department of Satellite Information Sciences, Pukyong National University, Busan, South Korea
c Seafloor Sciences Branch, Naval Research Laboratory, Stennis Space Center, MS, USA
d Department of Environmental Exploration Engineering, Pukyong National University, Busan, South Korea
e Department of Marine Science, Pusan National University, Busan, South Korea
f Department of Oceanography, Pukyong National University, Busan, South Korea |
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| Abstract: | 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. |
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| Keywords: | geotechnical and shear properties microstructure SEM the East Sea |
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