Shinji Sato, Shohei Okuma


Destruction mechanisms of coastal structures due to the 2011 Tohoku Tsunami were investigated on the basis of intensive field surveys in the southern part of Fukushima Prefecture. Numerical tsunami simulation was utilized to estimate the tsunami force exerted to the structure. The large difference in water pressure due to overflowing tsunami is found to be the essential mechanism of overturning destruction of coastal structures. The destruction was enhanced by the generation of large impulsive force due to a turbulent bore and the local scour of the foundation. The seaside slope of the seawalls was found to be essential as more significant damage was observed for upright seawalls than gentle slope ones. Inland topography also exerted dominant influences on the destruction of seawalls due to receding tsunami. The joint between the parapet and the seawall basement was considered to be a weak point unless it was appropriately reinforced by steel bars.


tsunami; coastal structures; disaster mitigation

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