摘要
Tsunami caused by the Tohoku earthquake on March 11, 2011 washed away a lot of buildings and deprived many lives on unexpected scale. Seawall is one of the measures to reduce tsunami damage, but itself is also given great damages by tsunami. Study on mechanism of tsunami force acting on seawalls is also quite important and improvement of countermeasures is very important. Hydraulic experiments were conducted to estimate wave force and collision force by driftage due to tsunami on various conditions. The tsunami force reduction due to obstacles installed shoreline is examined and assessed by previous formula. Collision force by driftage due to tsunami is also investigated and assessed by previous formula.