Laboratory study of the combined wave and surge overtopping-induced normal stress on dike

Normal stress on dikes is one of the most critical parameters for a sound dike design. With more rapidly rising sea levels due to global warming, dikes are seriously threatened by overtopping induced by the combination of wave and storm surge. Compared with wave overtopping on positive freeboard, the curling breaking wave on dikes induced by the combined wave and surge overtopping may destroy the weakly protected dike crest and landward slope. Thus, in order to prevent severe damage to dikes, it is necessary to fully understand the normal stress induced by the combined wave and surge overtopping. In this paper, physical model tests were carried out to study the normal stress on dike induced by the combined wave and surge overtopping. Two characteristics of normal stress on dike were observed. The spatial distribution of normal stress on dike was also analyzed. It was found that the Weibull distribution can be used to effectively describe the statistical distribution of peak normal stresses. Furthermore, by curve fitting of the laboratory measured data, the Weibull factors on the part of the crest and the upper part of the landward slope were obtained.