A Consideration Aimed at Improving the Resiliency of Protective Structures Against Tsunami - Post-Tsunami Hazard: Reconstruction and Restoration - page 214

Fig. 14.13 Cross section of the widening work of resiliency structure

Fig. 14.14 Stateofwideningworkagainstoverlow(Arikawaetal. 2013 )

the tsunami but prevents scouring of the rubble mound foundation or the seabed.
The material for the widening work is riprap, which is used to build foundation
mounds. It is feared that if only riprap is used, the widening work will be scoured,
soarmorblocksareinstalledonthesurfaceofwideningwork.Still,iftheoverlow
scale increases, the covering work will be washed away and the widening work will
be scoured, so as a countermeasure, scouring prevention work is installed.
Arikawa et al. ( 2013 ) conducted physical experiments on the effect of widening
worksagainstoverlow.Wideningworkat1/3ofthecaissonheightwasperformed,
and its effectiveness as a countermeasure against scouring of the foundation mound
ofthewideningworkandtheseabedgroundduringtsunamioverlowwasveriied,
as shown in Fig. 14.14 .

14.5 Conclusions

In this paper, the protective effect of breakwaters at Kamaishi Bay has been consid-
ered using numerical simulations. At first, the effect of breakwaters against the 2011
tsunami has been verified by comparing the different states of damage to breakwa-
ters. The result shows that the breakwaters in the deep region had a protective effect