# Analysis of Multilayered Ground Amplification Characteristics by Scaled-Down Model Tests
## 5 Summary and Conclusions  
In order to experimentally confirm the acceleration amplification characteristics according to the difference in the physical properties of each layer in the multilayered ground and the amplification characteristics occurring at the inter-layer boundary, a scaled-down model experiment using the 1 g shaking table was performed to obtain the soil dynamic behavior. A dense lower ground was formed with a sample mixed with silica sand and sandy soil, and a loose upper ground was formed with sandy soil. Then, the acceleration was measured by applying a seismic loading through the 1 g shaking table test. The peak ground acceleration and spectral acceleration were shown with the measured response acceleration to illuminate the amplification change by depth of the scaled-down model and the amplification difference between each layer. In addition, calibrating and verifying the experimental results with DEEPSOIL results can make the experimental results more convincing and provide strong support for large-scale model analysis relying on  
Figure 17: (**a**) SA by artificial wave at surface; (**b**) SA by artificial wave at 0.1 m depth; (**c**) SA by artificial wave at 0.2 m depth; (**d**) SA by artificial wave at 0.3 m depth; (**e**) SA by artificial wave at 0.4 m depth; (**f**) SA by artificial wave at 0.5 m depth. the 1 g shaking table test by the law of similarity. In this study, the following conclusions were obtained:  
1. In the absence of resonance, experimental results under a sine 10 Hz wave showed that the acceleration increase of loose ground is larger than that of dense ground on multilayered ground by PGA and SA. In the cases of artificial seismic waves and sine sweep waves, resonance appeared at the top of the experimental model, resulting in the increase of acceleration. 2. The response spectral acceleration confirmed that acceleration was amplified with depth decreases, that the upper ground amplification factor was more amplified on loose ground, and that the lower ground amplification factor was less amplified on dense ground. Compared to the amplification factor of the multilayered boundary, the inter-layer boundary was found to be amplified to the middle of the lower layers. Moreover, the spectral acceleration amplification factor of the inter-layer boundary is between that of the lower layer and the upper layer. 3. Comparing the experimental results and numerical analysis results of the 1 g shaking table at different depths, it could be seen that the dense ground with 0.3-0.5 m had almost the same experimental and numerical analysis results. In addition, the surface layer that simulates the loose ground layer from surface to 0.3 m has some differences compared to the dense ground, but it has been found to predict the main amplification cycle well. 4. As a result of mutual comparison with the one-dimensional ground response analysis using DEEPSOIL, it was confirmed that the peak ground acceleration was generally consistent with the experimental value of each input seismic shaking. In addition, the difference between the experimental results and the numerical analysis results increases with the increase in height. The accuracy of the data is guaranteed by using multiple waveforms to simulate the multilayered ground. 5. In this study, scaled-down model experiments were carried out based on a 1 g shaking table. Overall, the results obtained using the DEEPSOIL numerical analysis software compare well with the 1 g shaking table test results performed on multilayered ground. However, there are still some limitations in using DEEPSOIL. In the future, we will focus more on large-scale flat ground and slopes, use 2D/3D simulation software for numerical simulation analysis based on the 1 g shaking table test, and study actual cases to analyze the dynamic behavior of soil. Writing--original draft preparation, Y.J. and H.K. ; Review and editing, D.K. ; Date acquisition Y.J., S.J. and H.K. All authors have read and agreed to the published version of the manuscript.