Applicability of tracking simulations for probabilistic assessment of floating debris collision in tsunami inundation flow

Abstract

To improve the applicability of numerical simulations in tracking debris motion for probabilistic assessments of debris collisions with buildings and components installed in coastal industrial sites at a local scale (O (1 km)), the applicability of the numerical approach is investigated through numerical simulations of laboratory experiments. Two characteristic phenomena are found that cannot be expressed by the numerical simulations. The first characteristic phenomenon is debris motion approaching a building model in a reflected wave. To simulate this phenomenon, the incorporation of a turbulent bore model into the numerical model is proposed. The second characteristic phenomenon is debris diffusion due to various perturbations. For simulation of this phenomenon, two approaches are proposed. In the first approach, some causes of debris diffusions are separately modeled. In the second approach, diffusions due to various perturbations are simulated by artificially intensifying debris diffusions. By investigating impacts of the two approaches on probabilistic assessments of debris collision, it is found that debris spreads and the exceedance probabilities of collision speed can be predicted well by considering epistemic uncertainties in determination of diffusion intensity by the latter approach.