MODELLING OF DEBRIS MOTION DRIVEN BY TSUNAMI WAVE BREAKING

Abstract

When a giant tsunami approaches onshore, offshore vessels and other floating objects move following the current of the tsunami. Some of the waterborne debris are transported to tsunami inundation areas and those debris impact buildings. For evaluations of debris impact loads, types of debris having the potential to impact and damage the structures are identified by considering debris impact hazard region. According to ASCE7-22, the debris impact hazard region shall be determined by the empirical model proposed by Naito et al. (2014) in a simple manner. Furthermore, numerical debris transport modelling using massless tracers also shall be permitted to use for the determination. On the other hand, numerical debris tracking (nDT) modellings which solve the equation of motion of debris have been developed (e.g., Kihara and Kaida, 2019). In this study, a surface roller modelling is incorporated into the nDT model of Kihara and Kaida (2019) to simulate debris motions driven by tsunami wave breaking. To validate the model, simulations of hydraulic experiments focusing on the motion of offshore debris reported by the Nuclear Regulation Authority (NRA) of Japan are carried out (Oda et al., 2021).