Journal of The School of Marine Science and Technology,Vol.3 No.2
A Study on Wave Transformation and Wave Forces Acting on Gravity Navigation Aid Towers Fixed onto a Sloping Seabed
Kinji SEKITA, Yukio NOMOTO, Takehiko YOSHINARI, Akira SHIMOJI
and Hirokazu ISHIKAWA
Abstract
Navigation aid towers fixed onto the seabed have been constructed by Japan Coast Guard to indicate their positions and avoid collisions of ships with offshore facilities such as manmade islands. These kind of structures, composed of a column and gravity base,are often installed on reefs close to shore.While an impulsive wave pressure is said to act on the circular column above sea surface,the large wave force also acts on the box shaped base.Though the wave force on the column has been evaluated by a conventional formula, there is no appropriate formula applicable to the base.Therefore,in order to develop an evaluation method,we conducted a series of model tests to measure wave forces on a pipe and a box shaped base,together with pressures induced in the pipe.Furthermore,we conducted numerical analyses by using the potential theory and Navier Stokes theory to simulate the measured wave forces and wave transformations run-up on 1/30slope. The paper describes a comparison of experimental and analytical results together with the evaluation of the wave force calculation method developed.
     
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