A numerical model is proposed for the estimation of wave transformation characteristics and motions of a pile-supported floating breakwater. The model takes account of friction force between rolllers and piles, where nonlinear Coulomb friction is linearized by using equivalent damping coefficients. Experimental results are compared with the calculation results, which shows significant wave energy dissipation and attenuation of floating body motion because of the friction effect.

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Two kinds of resonant oscillation due to transient ship-generated waves are studied from the viewpoint of dynamic response of the mooring system, where ship-generated waves are idealized as a wave packet. Short periodic resonance with the same period as ship-generated waves is discussed compared with steady-state response due to monochromatic waves. Long periodic resonance due to slowly-varying wave drift force associated with grouped waves is also investigated including transient free oscillation of the system.

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This paper is aimed to investigate the pertinent characteristics of velocity field of nonlinear crossing waves in finite water depth, based on the laboratory experiments and the 3rd-order crossing wave theory. The 3rd-order crossing wave theory is shown to estimate well the experimental results. In case that the directions of two wave trains are different, the velocity direction of crossing waves is different in water surface and bottom. In addition, the skewness of water particles of crossing waves is fairly affected by each wavelength of two wave trains and crossing angle.

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A fluid motion at permeable layer constructed model of precast concrete armor unit was visualized in ossillatory flow. Many turbulence measurements have been ever done by point measurement techniques such as LDA. In this study, a method of measurement has been conducted by a particle tracking velocimetry for 2-D space. It has been composed of Kalman's filtering theory, the Chai-Square-test and initial evaluation of velocities of particles which newly appear in the flame. Images of 30μm diameter particles were taken using a ultra high-speed video camera and Argon-ion laser slit illumination.

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This paper aims to discuss the velocity field around large cylindrical structures under wave action, based on the laboratory experiments and numerical calculation. The wave-induced currents around large cylinders are revealed to direct offshoreward through the whole depth except near bottom and above the wave trough. When the diffraction parameter D/L (D is the diameter of a cylinder, L is the wavelength) is large, the wave height and velocity change complicatedly in space.

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A manual of bottom sounding was made by selecting Lake Biwa for the case study area. Practical points necessary to enhance the accuracy of the survey were especially emphasized. The method to determine the appropriate cross-shore length of the survey line is discussed with respect to the critical depth for beach changes. The overall distribution of this critical depth in Lake Biwa is given.

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The completion of development of the pollution control fence needs its perfect recovery with safety. The gravity-type sinker is popular for the floating silt curtain. Because of its handling and cost performance, the H-section steel is widely used for anchoring the floating silt curtain. It is known that H-section steel anchor has enough holding power in comparison with its weight. The response of H-section steel anchor under the mooring force acting through the wire is investigated in this paper. The numerical evaluation of H-section steel anchor response employs the fluctuating tension measured in the field. The H-section steel anchor has the suction in addition to the gravity. The effect of the suction on the anchor response is also numerically investigated.

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The pollution control fences are developed on sites under constructing coastal structures, dredging or reclamation in order to prevent marine pollution. Some of the fences developed for long term are damaged or deteriorated due to the growth of marine organisms on fences. For practical purpose on designing the pollution control fences, the growth of marine organisms have to be quantitatively evaluated. This study investigated their growth on fences at Kan-on marina and Itsukaich sites. The blue mussel is numerically/quantitatively superior. The blue mussel dominates over whole water depth. The average submerged unit weight of each side of fence is 5.0kgf/m². The growth is affected by environmental condition such as temperature of sea water, current velocity, tide and so on. Accumulating field survey of the growth of dominant organisms at many locations, design method for their growth would be proposed.

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In the marine construction work, many working crafts are used under the severe wave conditions. As for working crafts, motions influence on the efficiency of works. Up to this time, the judgment to continue or suspend the work is done by men based on the experience.
In this study, the system which observes the motions of working craft and displays the motions is developed. The field tests to evaluate the accuracy of this system were carried out in offshore site of the Port of Sendai.
This system supports the judgment for execution or interruption in marine construction works.

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The present, a gentle slope revetment is construct at coast all over Japan.It is thinking that this revetment dissipate a wave energy at friction loss of a wave is slithering up it. But it is clearly that there is a trouble of higher wave run up the field observation compared with the hydraulic model test.
This thesis give a example and discusses the difference between the wave run up phenomen of the hydraulic model test and the field observation. A countermeasure method, this thesis propose the new type structure a gentle slope revetment.

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Artifical concrete blocks instaled in the sea for wave dissipasion sometimes need to be carried or removed for the expansion or redevelopment of existing port fasilities. Tying up this type of block with a rope either by workers on the sea or by divers at the bottom is always a risky operation. And carrying out any operation which involves the worker or diner having to approach and rope those blocks provides less productivity. Under these circumstances, a more efficient type of quipment is developed both to carry or remove those blocks from the sea by means of an endless chain on a less expensive basis and to guarantee the lives of worker' lives. In addition the expected results are attained during sea trials of the experiment.

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Recently, enlargement of port facilities towards offshore zones or reconstruction of existing facilities has been requiring the removal or replacement of armour blocks used in breakwaters or quay walls. During the blocks removal, usually a diver slings a wire rope around each block and then crane lifts it. This task may be therefore inefficient and very dangerous for the diver. In this paper, the authors introduce an improved orange peel type grab bucket which makes the removal of armour blocks safe and efficient. The results obtained from tests performed with both a model of this equipment and its prototype are also presented.

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In response to rapid constructions for marine structures, the authers hav conducted structural reserches on composite prestressed concrete structures, which consist of precast concrete blocks and filled-in concrete and steel pipe pile.
Connections between precast concrete blocks of this method are bonded by epoxy resin of underwater-setting. To verify the reliability of the joints, a bending test was executed on specimens which were actually undersea. As long as the connection work is completed within 90 minutes of the application of adhesive, either in the air or underwater, the analysis of the test results shows that the bending and tensile strength of the joint can maintain values of 0.8 times and 1.5 times more, respectively than those specified in the Standard Specification for Design and Construction of Concrete Structures by the JSCE.

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This study is concerned with the development of a new floating pier for marina. This flexible floating piers consists of many small pontoon units and is moored by chains. The dynamic behavior of the floating piers due to waves is investigated through laboratory tests. The motions and the tension forces of mooring lines of the piers were compared with those of a rigid type floating piers under various wave conditions. The results show that the flexibility of the joints is a dominating parameter for the movement the floating piers for the marina

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The increase of land price or limitation of developing areas leads to shortage of parking spaces. One of these cases is for Nagasaki City. We have proposed a floating deck on the sea as a parking space. Floating decks can eliminate or reduce environmental problems compared to reclamation or structures which need excavation or piling. And it is a movable parking lot.
This report introduces an example of a floating structure used as a heliport and describes an assembling and vehicle loading experiment of a prefabricated floating parking deck in a pond.

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Pricing marina slip rental fees is a crucial financial consideration in marina planning. Unfortunately it is often very difficult because fees vary widely with the location, access and profile of boating age residents in the primary market. A new computer system that calculates standardized price units (such as Yen/foot of rentable slip of proposed marina) has been developed to overcome these problems. The computer system analyses a large database of current slip prices for existing marinas then calculates demand projections and standardized pricing using various indicators of social and economic conditions. The system therefore facilitates regional strategic planning exercises.

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