Experimental and numerical investigation of tsunami behavior around two upright sea dikes with different heights

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.

KEYWORDS:

• 2011 Tohoku Earthquake and Tsunami
• cross-section changing dikes
• hydraulic experiment
• inundation
• OpenFOAM

Acknowledgments

The present work was performed as a part of the activities of the Research Institute of Sustainable Future Society, Waseda Research Institute for Science and Engineering, Waseda University. Furthermore, the work was also financially supported by the Penta-Ocean Construction Co., Ltd under Grant B2R500518101. Two anonymous reviewers made insightful comments that allowed the authors to improve the quality of the manuscript, and their contribution to this research is also kindly acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Penta-Ocean Construction Co., Ltd [B2R500518101].