Fig. 1

Cross-sections of embankment models used in numerical experiments. Embankment height and crest width are 4 m. The gradient of the embankment slope is 1:2. The first layer immediately below the embankment crest has the same depth in both models. a Model A. The boundary between the first and second layers is horizontal and at the bottom of the embankment. b Model B. The boundary is not horizontal and is partially in the subsurface