## 2 Materials and Methods  
### Soil Properties of Saemangeum Ground and Dreged Sand  
Based on bathymetric and topographic data, the depth distribution of Saemangeum Lake ranges between EL(\(-\)) 45.0 m to EL(\(+\)) 4.0 m, and the terrain is mostly low due to the nature of deep-sea reclamation. In the lower reaches of the alluvial area of the Mangyeong River and the Dongjin River, the soil depth is deep with poor drainage. The electrical conductivity of the soil is in the range of 10 to 30 dS/m, which varies depending on the region. Several site investigations were conducted to assess the soil profile, soil distribution, and grain size. The soil profiles at a site in Saemangeum (Figure 3) based on the cone penetration test (CPT) are shown in Figure 4. The soil type was evaluated based on the method proposed by [PERSON] (1965). The soil profiles show that the Saemangeum ground at the area is composed of sand from the surface up to about a depth of 10.0 m. After a depth of about 10.0 m, the ground is mostly composed of clay. Liquefaction assessment based on CPT results showed that the sand at the top portion of the ground is susceptible to cyclic liquefaction. Further investigation of the soil distribution across Saemangeum is shown in Figure 5, and it can be seen that the ground surface is constituted of sand, loamy sand, sandy loamy soil, and silty soil. In the Saemangeum gateway project (Figure 3), and after land reclamation of the area, the variation of the grain size distributions of the Saemangeum dredged soil was also investigated, as shown in Figure 6. In Figure 6, the Haje sample (Figure 3) is the soil used in the shaking table test conducted in this study. P-1 and P-2 are the samples obtained near the discharge point in the Saemangeum gateway project, and P-3 is the sample obtained near the spillway in the Saemangeum gateway project. As shown, the Haje silty sand, along with P-1 and P-2 of the reclaimed ground of the Saemangeum gateway project, is categorized as the most likely liquefiable soil based on the boundaries defined by [PERSON] (1965). For P-3, it is categorized as potentially liquefiable soil as it is composed of finer particles. P-3 is finer than P-1 and P-2 mainly due to the segregation of particles. Coarse particles tend to settle near the discharge point while large amounts of fine particles are being carried away into the direction of where the spillway is located. A standard penetration test (SPT) was also conducted at a site in Saemangeum (Figure 3), as shown in Figure 7. In Figure 7, BH-1, BH-2, and BH-3 are SPTs conducted near the gateway project, while BH-4 is conducted at the Haje port. Results show similar blow count distribution with depth for the four tests. Based on the SPTs, it can be seen that the soil at depths ranging between 0-2.5 m has low blow counts. In addition, the soil at depths ranging between 0-5 m was confirmed to be silty sand based on laboratory experiments. A summary of the properties of the Saemangeum silty sand used in the shaking table test are shown in Table 1.  
Figure 4: Soil behaviour classification with depth based on the cone penetration test. Figure 5: Soil distribution in Saemangeum, South Korea at shallow depths. Figure 3: Site investigation at Saemangeum, Republic of Korea. Sanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD) analysis were also conducted. Based on SEM, as shown in Figure 8, the soil consists of particles with sizes ranging from 74.5-203 \(\upmu\)m, classifying it as very fine sand to fine sand based on the diameter limits given by the United States Department of Agriculture (USDA). In addition, it can be seen that the soil sample contains smooth and rough angular particles that are either near-spherical or cylindrical. The results of the XRD analysis, as shown in Figure 9, indicate that the Saemangeum silty sand contains 73.2% silica (SiO2), 12.7% aluminum oxide (Al2O3), 3.98% iron oxide (Fe2O3), and 3.94% potassium oxide. Silica is known for its ability to absorb moisture, which arises from the numerous small pores present in it.