Abstract
　The purpose of this paper is to estimate the seepage force which generates in a permeable layer around coastal dike by breaking waves. Studies in the case of the non-breaking is already reported. The variation of the seepage brce is one of the important factors which control the stability of coastal dike. The seepage force is analyzed with the finite element method and the efects of wave characteristics, the penetration depth of dike, the slopo of dike and the scour hole at the toe of dike etc. are investigated.
　It was foumd that the seepage force around the sea dike decreases when the slope of dike is gently and block dike is created in front of dike. The seepage force around the end of wall is founded to decreases with the incremen of wave steepness and the increment of the penetration depth of dike. In the case of a scoured hole in the toe of dikes, the variation of the seepage force is found to be enlarged around the end of the wall.

【キーワード】：海岸護岸，浸透力

* 愛媛大学大学院連合農学研究科
United Graduate School of Agricultural Sciences, Ehime University.
**高知大学農学部
Faculty of Agriculture, Kochi University.