Study on Collision Probability of Tsunami Debris with Structures Using a Hydraulic Experiment

Abstract

In considering the secondary damage of a tsunami, it is important to consider whether a container placed in a port will collide with structures behind in the run-up tsunami wave. Therefore, we conducted a hydraulic experiment to investigate the behavior of tsunami debris due to the run-up wave. As a result, not only the run-up wave but also the reflected wave generated by the structure behind was important when we examined the drift of the tsunami debris. Therefore, we examined the influence of the length of the reflected wave on the drift behavior by changing the initial position, initial angle, and weight of the tsunami debris. We confirmed that the length of the reflected wave had a significant effect on the impinging speed of the reflected wave, the collision speed at the reflection wall, and the collision probability at the reflection wall. The collision probability decreased because the length of the reflected wave increased as the distance from the initial placement of the tsunami debris to the reflection wall increased. The collision speed could be roughly estimated based on the time when the run-up wave and the tsunami debris collided with the reflection wall. Furthermore, when numerical calculations were used to simulate our laboratory experiments, the calculated results were roughly consistent with the experimental values.