Experimental study on tsunami mitigation effect of pile-type porous tide barrier

Damage to coastal levees and breakwaters due to the tsunami in the Great East Japan Earthquake in 2011 have brought up issues on the necessity of improving the tenacity of these structures. Use of piles in these structures will be effective in enhancing their tenacity. Among several possibilities in structural types of these structures with piles, a pile-type porous tide barrier is expected to be helpful in reducing the tsunami load that passes through it and preventing the existing structures from collapsing. This paper introduces model tests examining the effect of the pile-type porous tide barrier in reducing the surge-type tsunami load. Based on several test results with different porosity ratios and a theoretical approach to interpret the experimental data, it was found that the tsunami mitigation effect of the barrier can be captured by loss factor, which can be defined by combining the porosity ratio and the friction factor.