Takuya Shiraishi
Field survey of bridges damaged by tsunami and the evaluation of the resistance of bridges and-the wave power of tsunami
Kyuichi Maruyama
In this study, we investigated an overview of the damage of bridges by the tsunami in the Great East Japan Earthquake from the satellite photograph.
Moreover, we conducted field survey of every washed away bridge. We checked the damage of each bridge and measured dimensions of bridges.
As a result of the survey, it is cleared that the number of bridges that were washed away or slided in the tsunami of the Great East Japan Earthquake was 252 in total.
From the comparison between the degree of damage and the frictional resistance, we found that we cannot predict the risk of damage without thinking about the power of tsunami. Therefore, we estimated current velocity from the immersed depth at the location of each bridge. Data selection was also conducted to obtain more reliable results.
As a result, the accuracy of damage prediction is improved somewhat. However, I have to say the accuracy of damage prediction is not still enough especially for bridges that have small resistance to acting force ratio.
It is necessary to estimate the accurate current velocity. Then, the applicability of Kosa”Ēs expression should be verified again.
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