Takako Fukuyama

Tsunami Wave Force Acting on Axisymmetric Caisson Foundations

Tsunami wave force acting on the axisymmetric caisson foundations was investigated through the hydraulic model tests. Water surface profile of tsunami caused by the 2011 off the Pacific coast of Tohoku Earthquake observed 11m deep and 3km offshore of Choshi city (Fukumoto et al. , 2012) was used as the incident wave. By using the pumptype tsunami wave maker the observed tsunami profile was well reproduced in the wave-basin. Tsunami wave pressure distribution and wave forces acting on the axisymmetric caisson foundations were measured. Based on these experiment data, a mathematical formula expressing peak wave pressure distribution with the parameter of the incident tsunami height was proposed.

REDUCUTION OF WAVE FORCE ON A LONG CAISSON OF VERTICAL PLACED ON THE COMPLICATED SUBMARINE TOPOGRAPHY

As the length of a caisson becomes long, the wave force per unit length becomes smaller because of the wave phase difference. In this study, we performed hydraulic model test on a long caisson placed on the complicated submarine topography model under various wave conditions in order to investigate the characteristics of wave reduction.It is found that the wave force on a long caisson placed on the complicated submarine topography is reduced significantly in the case of oblique waves. The reduction ratio for multi-directional random waves is smaller than that for uni-directional random waves due to directional spreading. In the case of head-on waves, wave force per unit length on the long caisson becomes smaller because of the dispersion of the wave height and the phase due to wave refraction.