Abstract
Since the coastal areas of the Tohoku region were extensively damaged by the tsunami caused by the Great East Japan Earthquake (Mw9.0), “Persistence” is now needed for the breakwaters along the coast. One of the reinforcement methods to realize this persistence is embedding steel pipe piles behind the caisson and filling the space between the caisson and piles with rubble. This paper attempts to reveal the reinforcement mechanism using an FEM simulation for the lateral loading experiment. As a result, it is shown that the lateral load act on the caisson is transferred to the piles via the filling and seabed layer. Also, the piles seem to resist the load by utilizing the soil resistance. When the friction between the caisson bottom and the ground reaches the maximum value, the yield load of this reinforcement method comes. After the yield load, the reaction force from the filling keeps increasing with caisson deformation. This is considered to cause persistence, and the resistance force depends on the specification of the piles. In the case of high stiffness piles, this reinforcement method is considered to obtain a high constraint effect on the filling, and there is a clear load transfer via the filling.
