Abstract
Many breakwaters were damaged due to the 2011 Tohoku Earthquake Tsunami. The authors have conducted a field survey, and found that damage to the caisson-type breakwater was limited where friction-increasing asphalt mat (herein after referred to as FAM) was used. In order to investigate the resistance performance of FAM against tsunami wave force, a series of hydraulic model experiments were carried out. The remarkable findings are stated as follows. 1) Caissons with FAM can resist larger tsunami wave force compared to those without FAM. 2) In case that FAM is not in use, caisson sliding occurs immediately after caisson starts to move. In contrast, when FAM is installed, caisson moves gradually in proportion to water level increase before sliding. This suggests that FAM can increase toughness of caisson-type breakwaters. 3) The reinforcement block has the ability to increase the resistance force against caisson sliding, especially when it is laid on FAM.
