**3.1. Test conditions**

The centrifugal loading tests were conducted under 50-G with a 1/50 scaled model. In this experiment, the model with a height of 100 mm and upstream and downstream gradients of 1:1 was used. **Figure 4** shows the schematic view of the model. The model was made from

**Figure 4.** Schematic view of the model and soil box for centrifugal loading test. (a) Schematic view of the model; and (b) the situation of soil box for centrifugal loading test.

No. 7 silica sand and kaolin clay with the mixture ratio of 8:2 by dry weight. **Figure 5** shows the particle distribution of the mixture. The water content of the mixture was 13%. In order to evaluate the seismic behavior of the model, the gauge points were placed on the surface of the embankment model and the reference points were set at the foundation. The total number of the points is 82. To reduce the friction between embankment model and wall of the soil box, the silicone grease was painted on the wall surface. The accelerometers were installed on the foundation. The foundation was made of rigid material. By assuming that the distance of the reference points on the rigid foundation is not changed, the coordinate of the gauge points is calibrated.

The model was excited with a horizontal sine wave of 50 Hz whose amplitude is 1.5 mm. The input seismic wave corresponds to the earthquake ground motion with a peak acceleration of about 300 gal, and the frequency is 1 Hz.
