1995 Fiscal Year Final Research Report Summary
Evaluation of the characteristics of sediment in coastal shallow sea area and development of the prediction method for maddiness environment
| Project/Area Number |
06556039
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| Research Category |
Grant-in-Aid for Developmental Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
Irrigation, drainage and rural engineering/Rural planning
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| Research Institution | Kyushu University |
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Principal Investigator |
TAKAYAMA Masateru Kyushu University, Faculty of Agriculture, Professor, 農学部, 教授 (60038312)
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| Co-Investigator(Kenkyū-buntansha) |
MORI Ken Kyushu University, Faculty of Agriculture, Assistant Professor, 農学部, 助手 (50117272)
SHIKASHO Shiomi Kyushu University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (80038265)
TOHARA Yoshio Kyushu University, Faculty of Agriculture, Professor, 農学部, 教授 (80038182)
HIGASHI Takahiro Kyushu University, Faculty of Agriculture, Assistant Professor, 農学部, 助手 (00181066)
OHTSUBO Masami Kyushu University, Faculty of Agriculture, Associate Professor, 農学部, 助教授 (80112316)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Sediment / Turbidity / Physical and chemical properties / Mechanical properties / Resuspension / Settling / Convective Dispersion / Numerical simulation |
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| Research Abstract |
Fine particles transported from rivers are deposited in an inner part of the bay, forming a vast tidal flat. The suspended materials and mud particles in estuaries bring about some environmental problems during the construction work in the sea. Establishment of the methods is needed to estimate the settlement of slurry clay and diffusion of muddiness in sea water. In the present work, some characteristics of the sediments and the transportation of the suspended mud particles have been studied.
The physico-chemical and mechanical properties of the surface sediment and the distribution of benthos in a tidal flat have been investigated. The results showed that the surface sediment exhibits constant clay mineral composition throughout depth, and overconsolidated state in view of the shear strength and consolidation characteristics of the sediment. It was also indicated for Imazu estuary area that a positive correlation exists between clay and organic contents in the mud, and the weight of c
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apitata per unit area was the maximum at around-150mV redox potential. A method was proposed to determine the geotechnical parameters for the settlement of slurry clay, and the relationship of the time and the amount of consolidation was explained by the consolidation equation which took into account the friction inside of the ring.
The occurrence of turbidity was formulated in terms of the relative correlation of the shear strength of mud against the yield stress of the sediment surface zone, based on the annular flume experiments and the on-site observation of tidal current velocity and the concentration of suspended mud particles in Isahaya Bay. Turbulent diffusion coefficient and settling velocity of the suspended mud particles were found, from the open channel experiments, to be dependent on the shape of power spectrum of the velocity fluctuation.
Based on the results thus obtained, the code to estimate the muddiness in coastal sea has been developed and numerical simulations were conducted for Ariake Sea, and the numerical model was successfully coded. Less
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