# Effect of Soil Box Boundary Conditions on Dynamic Behavior of Model Soil in 1 g Shaking Table Test
## 2 1 g Shaking Table Test
### Configuration of Test Program  
The test models were divided to analyze boundary conditions depending on wall conditions of the soil boxes before the test. Five cases were presented depending on the soil boxes to be tested, the slope of ground model (geometric shape), and the presence of sponge on the wall in the direction of vibration. Load input was 3 sine waves (0.07 g, 0.1 g, 0.154 g) and an artificial seismic wave (0.18 g). In other words, 4 types of loads were inputted after setting up 5 cases to conduct the dynamic model test 20 times (Table 2). Figure 5 shows the waves entered including the sine wave and the artificial seismic wave at different acceleration levels. The sine wave was selected to be 0.07 g, 0.1 g and 0.154 g of 2 Hz. In order to confirm that the effect of the boundary condition changes with the size of the load, we tried to exclude elements other than the load as much as possible. Therefore, a simple long-cycle sine wave, 2 Hz, was selected so that resonance does not occur due to the natural period of the shaking table or box. The 2 Hz sine wave of 0.07 g was selected to examine the effect of boundary conditions, when applying the small enough load and the long-period waveforms without significant amplification, for each height of the scale model to be tested. The artificial seismic wave is the synthetic seismic wave combining the Gyeongju-Pohang earthquakes, using the empirical Green's function on the basis of the raw data measured in the Kori Nuclear Power Plant. As the artificial seismic wave has different periodic components, high amplification occurs. This is why the artificial seismic wave was selected to evaluate the effects of boundary conditions in the case of high amplification. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Case** & **Soil Box** & **Slope** & **Sponge** & **Input Wave** & \\ \hline
1 & & & – & 0.07 g \\
2 & RB & Flat & 50 mm & Sine wave & 0.1 g \\
3 & & (Height 50 cm) & 100 mm & & 0.154 g \\
4 & & & 150 mm & Artificial earthquake & 0.18 g \\
5 & LSB & & – & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Classification of test model and input wave. Figure 4: Instrumentation: (**a**) Accelerometer; (**b**) Data logger. Figure 6 shows the locations of measurement by the accelerometer installed in the center of the soil box and the walls therein, which are 10 cm, 30 cm, 50 cm high, respectively, from the bottom. The accelerometers for the model test using the RB of Case 1 and the flexible soil box of Case 5 were installed, as shown in Figure 6a, to analyze acceleration changes at the same locations. Although each ground length is different because of the added sponge in Case 2, Case 3 and Case 4, the center and heights of the ground were the same, as shown in Figure 6b-d. The accelerometer buried in the walls were spaced 5 cm apart from the wall and the sponge. This aims to observe changes of response acceleration amplification between the center and the wall of flat ground occurring depending on boundary conditions of the soil box at the center and the wall, for the same height. All cases were homogeneously constructed with the same compaction and water content using the same soil. For the model, the relative compaction was 70%; the optimum water content was 12.5%; the void ratio was 1.055; the dry unit weight was 12.79 kN/m\({}^{3}\), and the moist unit weight was 14.22 kN/m\({}^{3}\). For the RB supported with a sponge, the sponge was attached before creating the ground, and the soil can be compacted by means of lateral pressure while creating the soil where the rigidity of sponge is too low. For selecting the sponge of which the density is not greater than the density of created ground, the selected sponge was 0.49 kN/m\({}^{3}\) in density and 15.6 kPa in hardness (resistance to deformation). Figure 7 shows the shear wave velocity (Vs) measurement equipment in the shear wave velocity test, used to examine the characteristics of the ground model by [PERSON] [12].