ABSTRACT

The 2011 Tohoku Tsunami caused severe damage to many coastal defenses along the Japanese coastline, including areas where two adjacent upright sea dikes of different heights met. There are many places along the coastline where structures of different heights and shapes meet due to the various design codes. In this study, the authors aim to examine the tsunami flow around such dikes by conducting three-dimensional hydraulic experiments in a tsunami wave basin and numerical simulations using the fluid dynamics model OpenFOAM. Twelve experimental cases were tested by changing the waveforms, and also by keeping the height of one side of the dike model constant while adjusting the dimensions of the other side. The results show that the difference in height between the structures significantly influences the volume of overtopping over the relatively lower dike and the inundation depth and velocity behind the dikes. Furthermore, different characteristics of inundation patterns are observed between the inundation depth and velocity. Hence, this study illustrates the necessity to re-assess the effectiveness of such structures against tsunami events.

抽象的

在2011东北海啸对日本海岸线上的许多沿海防御设施造成了严重破坏，其中包括两个相邻的不同高度的直立海堤相遇的地区。沿海岸线有很多地方，由于各种设计规范，不同高度和形状的结构会合。在这项研究中，作者旨在通过在海啸波盆地中进行三维水力实验并使用流体动力学模型OpenFOAM进行数值模拟来研究此类堤防周围的海啸流。通过更改波形，以及在调整堤防模型一侧的高度不变的同时保持另一侧的尺寸不变，对12个实验案例进行了测试。结果表明，结构之间的高度差异显着影响相对较低堤防上的覆盖量以及堤防后的淹没深度和速度。此外，在淹没深度和速度之间观察到不同的淹没模式特征。因此，这项研究表明有必要重新评估这种结构对海啸事件的有效性。