Abstract
　The purpose of this paper is to estimate the seepage force which is generated in a permeable layer around a coastal dike by non-breaking waves. The variation of the seepage force is one of the important factors which control the stability of coastal dikes. The seepage force is analyzed with the finite element method and effects of wave characteristics, the penetration depth of a dike and a scour hole at the toe of a dike are investigated.
　It was found that the effect of the penetration depth of dikes on the seepage force increases with the increment of wave steepness and the decrease of the relative depth. 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.

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