THE EXAMINATION OF COLLISION SPEED REDUCTION EFFECT OF TSUNAMI DEBRIS AT THE TIP OF RUNUP WAVE BY REFLECTED WAVE

Abstract

 We conducted a hydraulic experiment in case that tsunami debris set on the land model. The tsunami debris was drifted at the tip of a runup wave and collided with the reflection wall. Then, we examined the effect of reducing the collision speed due to the buffer effect which occurred at the tip of the runup wave that firstly collided with the reflection wall. We also conducted experiments under the several conditions to examine why the length of reflected waves become increase. We examined the effect of the water mass against the collision probability and the collision speed under the condition that the runup wave and the water mass reflected by the wall coexist. In addition, it became possible to evaluate the collision velocity from "the reduction rate of the drift speed due to the reflected water mass" and "the length of the reflected water". Furthermore, we succeeded to evaluate the collision velocity using the theoretical equation of reducing collision speed in the reflected wave, quantitatively.