EXPERIMENTAL STUDY ON WATERBORNE DEBRIS IMPACT ACTING ON TSUNAMI SEAWALL

Abstract

 The waterborne debris impact is one of the most important issue for the tsunami safety measures. Several evaluation methods have been proposed based on the experimental results, however, they are derived on the conditions where driftage was placed on land level and carried away by bore/surge tsunami. Therefore, the applicability of these evaluation methods for floating debris object such as a boat drifting from off-shore has not been confirmed. In this study, hydraulic experiments for the impact force of floating debris acting on seawall were carried out to investigate the characteristics of drift, collision frequency and strain energy of the tsunami seawall. In addition, from the viewpoint of comparison with the existing estimation formulas, a method to convert collision energy into collision force was derived, and the estimation formula of collision force by waterborn debris impact was proposed.