*2.1. Experiment Process*

The flume used in the experiment was 120 cm × 50 cm × 120 cm. In order to observe the variation in soil mass, the outer wall of the flume was made of transparent glass. In the flume experiment, the sediment thickness was set to be 45 cm, and the depth of overlying water was set to be 40 cm. The sediments used in the experiment were taken from the Yellow River Delta, and its median particle size was 0.058 mm. The particle-size distribution curve of these sediment samples is shown in Figure 1.

Prior to each experiment, powdery sediments were taken, and their contents were controlled at around 40%, we then added water to have a water content of 40%, and the powdery sediment was mixed with the stirrer. The deposited sediments were then transferred to the flume until the thickness of the sediment hit 45 cm; and the pore pressure sensors were then buried with a burial depth of 0 cm, 25 cm, 35 cm, and 40 cm, respectively, as shown in Figure 2. Afterward, water was filled into the flume, avoiding the formation of erosion pits on the surface of the soil mass during the water-filling process due to high water-filling speed, and we stop adding water when the height of the water filling reached 40 cm. We kept the model flume still for 24 hours after its preparation was finished in order to complete drainage consolidation. We then performed manual wave generation with the duration of 1 hour each day and proceeded for 7 consecutive days. Simultaneously, we measured the pore water pressure and observed the experimental phenomenon. We discharged the overlying water body

when the experiment ended, and determined the penetration strength of the soil mass with a micro penetrometer at different depths. *J. Mar. Sci. Eng.* **2019**, *7*, x FOR PEER REVIEW 3 of 10

*J. Mar. Sci. Eng.* **2019**, *7*, x FOR PEER REVIEW 3 of 10

**Figure 2.** Schematic diagram of wave flume. **Figure 2.** Schematic diagram of wave flume.
