# Analysis of Multilayered Ground Amplification Characteristics by Scaled-Down Model Tests
## 1 Introduction  
Multilayered ground consists of two or more layers with different material properties, stratum density and shear wave velocity. Ground amplification is caused by differences in impedance at each layer. Therefore, the amplification characteristics of the ground are determined by the differences in the physical properties of each layer that constitutes the ground. In order to confirm this through model tests, a multilayered ground model was created and to observe changes in the behavior and amplification characteristics between layers under seismic loading. To this end, two or more different materials forming a multilayered ground were used to identify each property, and test methods suitable for multilayered ground were explored and carried out. In order to understand the complex ground behavior during earthquakes, several experimental studies have been carried out using the 1 g shaking table test. However, most of the studies were systematically performed by changing the ground conditions such as soil material, density (water content), inclination angle of the slope, and ground water level [1]. [PERSON] et al. [2] produced bedrock using well-graded gravel, cement, and water at a weight ratio of 90.1%\(\times\)3.6%\(\times\)6.3%; the dynamic strain during shaking was successfully measured to understand the generation of shear strain. [PERSON] [3] studied the influence of pore water saturation on the horizontal and vertical components of ground motion in multilayer soil bedrock system under the action of inclined SV wave. Only a few studies have proposed the characteristics of the input motion, in which the peak ground acceleration is also the main focus, just few studies have focused on the frequency characteristics [1]. [PERSON] et al. [4] compared the relationship between the dominant frequency of the input ground motion and the natural frequency. [PERSON] and [PERSON] [5] showed that theacceleration amplification rate is different between the center and edge of the crest using the centrifugal model tests. [PERSON] et al. [6] conducted a numerical study of the dynamic behavior from deformation to failure of a slope model (including various inclined weak layers) using shaking table tests. [PERSON] et al. [7] studied the stability of a nonhomogeneous slope with cracks under earthquake action. The failure mechanism of a nonuniform slope with cracks was proposed for the first time using the discretization technique. According to the obtained numerical and laboratory test results, [PERSON] et al. [8] concluded that the carefully selected large geometric-scale coefficients for the soil-structure model used in the small-scale shaking table experiments can capture the dynamic response of the full-scale soil-structure system with acceptable accuracy. [PERSON] et al. [9] studied the influence of natural frequency on slope dynamic characteristics. Numerical and experimental results show that the high frequency component and low frequency component mainly cause local deformation and whole deformation of the surface slope respectively. [PERSON] et al. [10] introduced shaking table tests to resolve the response differences between underground shafts and tunnels during earthquakes, to evaluate their impact on structural performance, and to verify the proposed model by comparing test and analysis results. [PERSON] [11] used the 1 g shaking table test to analyze slope instability. The slope model consists of three layers: surface layer, weak layer and base layer. The applicability of the Newmark method is verified. As we know, foundations are made up of many grounds of soil. It is very difficult to capture the dynamic characteristics of soil during an earthquake at a real site. Usually, it is difficult to create actual natural rock, and it is common to imitate the bedrock by mixing sand, cement, or silica due to the high risk of failure.