Experimental investigation of mechanisms leading to tsunami-driven debris damming on elevated structures

Document Type

Article

Publication Date

4-15-2026

Abstract

This study aims to understand tsunami-driven debris damming mechanisms by quantifying the debris dam characteristics, including their effects on damming forces, and assessing the key influencing factors of debris, flow, and the built environment that define debris dam characteristics. Experiments were conducted at a 1:20 scale to mimic tsunami-driven debris damming at an isolated column structure. The test combinations consisted of six wave conditions, three column arrangements, and two types of debris shipping containers. Dam characteristics, including dam volume and the number of debris objects in the dam, were measured through visual measurements, while the submerged frontal area of the dam was estimated using a photogrammetric method. Corresponding loads were measured on the entire structure and an individual column in the front row using a force balance plate and a multi-axial load cell, respectively. As per findings, the submerged frontal area, later converted to the blockage ratio, has the highest correlation with the increased damming load on the structure. The mechanisms leading to debris damming were determined through the effects on the blockage ratio by three interaction types: debris-debris, debris-flow, and debris-flow-structure interactions. Out of three interactions, debris-flow-structure interactions were found to be the highest influential mechanism leading to debris damming. As individual parameters, debris characteristic length, initial debris volume, closure ratio of structure, and relative size of debris were identified as positively contributing factors to increasing the blockage ratio, while higher Froude number of waves, debris dispersion, and debris velocity can decrease the blockage ratio.

Publication Source (Journal or Book title)

Coastal Engineering

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