Grant-in-Aid for Scientific Research (B)
|Allocation Type||Single-year Grants|
|Research Institution||NIHON UNIVERSITY JUNIOR COLLEGE|
MAENO Yoshihiko Nihon Univ. Junior Coll. , Professor, 教授 (90110139)
ISHIKAWA Motoyasu Nihon Univ. Junior Coll. , Lecturer, 講師 (40279766)
KUROKI Fusao Nihon Univ. Junior Coll. , Lecturer, 講師 (60102430)
INOUE Fumio Nihon Univ. Junior Coll. , Professor, 教授 (60147684)
SHIGEMATSU Takaaki Osaka City Univ. , Faculty of Eng. , Research Assistant, 工学部, 助手 (80206086)
AOKI Shinichi Toyohashi Univ. of Tech. , Faculty of Eng. , Associate Professor, 建設工学系, 助教授 (60159283)
畑中 勝守 日本大学短期大学部, 専任講師 (10259129)
山中 康資 日本大学短期大学部, 専任講師 (40259130)
|Project Period (FY)
1997 – 1999
Completed(Fiscal Year 1999)
|Budget Amount *help
¥11,500,000 (Direct Cost : ¥11,500,000)
Fiscal Year 1999 : ¥1,600,000 (Direct Cost : ¥1,600,000)
Fiscal Year 1998 : ¥1,600,000 (Direct Cost : ¥1,600,000)
Fiscal Year 1997 : ¥8,300,000 (Direct Cost : ¥8,300,000)
|Keywords||Silt Curtain / Field Observation / Current / Wave / Measurement / Tension / Holding Power / Floating Structure|
The field verification on the holding power of mooring anchors was conducted on the seabed composed of silt and sand in Maizuru Bay and Tokyo Bay. We employed the concrete block anchor and the suction anchor.
When the tensile forces acting on the mooring wires were measured, the pressure distributions were also measured at the bottom of the concrete block anchors and inside the suction anchor by varying the drawing angles of the anchor line or the drawing speed. Also, the field measurements on the behavior of silt curtain were conducted under stormy waves and currents. The field measurements were successfully completed and supplied the data required to estimate the drag coefficient of flared curtain structures. From the observation and analysis of I.he measured data during this period the followings are obtained.
1. The holding power shows the maximum value at the drawing angle of 90 degree, and decreases with the drawing angle. But this tendency is not remarkable at the drawing angle le
ss than 45 degree.
2. The concrete block anchor shows a sharp peak of the holding power when the drawing speed is large. When the drawing speed is small the pressure distributes unevenly along the bottom plane. The suction anchor always shows a peak of the holding power independently of the drawing speed. It was also confirmed that the negative pressure inside the suction anchor changes in proportion to the holding power.
2. The other data of tension shows the linear correlation between the static tension on mooring wire and the current velocity, up to a certain current velocity.
3. The drag coefficient for current is also large as same as that for wave while the current velocity is low, and gradually approaches to 1. 0 as the velocity increases. The drag coefficient for wave is considerable large while Reynolds number/the velocity of water particle is low, and gradually approaches to 1. 0 as the velocity of water particle increases.
5. Each of the drag coefficients for both stormy wave and current was predicted to be 1. 0. Since the large velocities of wave and current are induced at the same time by storm, the estimated drag coefficient of 1. 0 is reasonable to use for designing the flexible curtain structures under the wave and current. Less