The vertical telescopic breakwater(VTB), which is a new breakwater that permits the navigation of ships, remain at the bottom of the sea during calm and rise to the surface during tsunamis or storm surges. Kawai et al. (2017) and Arikawa et al. (2019) found that it is effective not only for swell waves, but also for long-period waves simulating tsunamis and storm surges by previous experiments and numerical analyses. However, there have been few studies on the performance of VTB by numerical calculations in actual ports using actual typhoons. In addition, sea levels and changes in characteristics of typhoon due to climate change are predicted to occur; hence, we are concerned about the damage in all quarters caused by storm surge inundation, especially at Tokyo. Therefore, in this study, we used hypothetical typhoons under worst-case scenarios and quantitatively evaluated the protection performance of VTB against hypothetical typhoons with different aperture rates of VTB in Tokyo Bay by the numerical simulation.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/qof5ixKqIiA

The objective of this study is to investigate experimentally the breaking limit of waves due to a submerged breakwater in a multi-directional random wave field. Experiments have been conducted in a 3-D wave basin equiped with a multi-directional random wave generator. In this study, a special type of wave gages has been employed to record the water surface fluctuations at wave breaking with favorable accuracy. This study investigates the influence of incident wave conditions and wave directionality parameter S. on the wave breaking limit. An equation has been introduced to predict the wave breaking limit in regular wave field using the least square technique applied to the results. This equation has been revealed to work well over a wide domain of wave conditions ranging from crossing waves to multi-directional random waves.

The breaking limit of multi-directional random waves is still unknown and is requested to be formulated numerically from coastal and ocean engineering viewpoint. In this paper, a breaking wave gauge is newly devised to measure the wave breaking inception as accurately as possible. Indoor laboratory experiments have shown that the breaking wave gauge is able to measure the breaking inception and that the breaking limit of multi-directional random waves becomes smaller than that of the regular wave. The critical wave steepness of multi-directional random waves is revealed to become smaller as the spreading parameter Smax increases.

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for water and transport engineering(No. 2618 the second road Binhai new district, Tianjin, China, 300456) 4 正会員 株式会社大林組(〒108-8502 東京都港区港南2-15-2 品川インターシティB棟)