Abstract
The abrasion process of block masonry seawall constructed on a gravel coast was investigated by field observation data. The movement characteristics of 50 kg rough stones due to wave action were disclosed by hydraulic experiments with a model scale of 1/25. The relationship between the wave height and the number of collisions was shown for three wave periods and four water level conditions. It was revealed that the movement of rough stones was the most significant when the still water level was the same as the top surface of rough stones. It was also found that the number of collisions increased with the increase in periods. The moving speed of rough stones was based on the result of video analysis on the stone movement pattern due to wave action. The characteristics of overtopping waves were investigated by hydraulic experiments with a model scale of 1/35. The abrasion rate of the block masonry seawall was estimated by the existing experimental formula using observed wave and tidal data at the nearest NOWPHAS station. The estimated abrasion rate was nearly the same as the observed value. Furthermore, a repairing method was proposed for the damaged block masonry seawall based on the results of the wave overtopping test.
