# Comparative Study of the Seismic Response Characteristics of Three Special Soils
## 1 Introduction  
Earthquake damage indicates that the damage of strong earthquakes to engineering structures is closely related to site conditions, especially the amplification effect of soil conditions on ground motion [1]. [PERSON] proposed that site conditions would have an impact on seismic motion after the 1906 San Francisco earthquake in the United States. Since then, in the postdisaster investigations of several major earthquakes, such as the Kanto earthquake in Japan and the Mexico earthquake, it has been found that the buildings on the soft soil sites are severely damaged. Under seismic loads, the internal structure of special soil is prone to damage, leading to a rapid decrease in strength, resulting in seismic damage such as soft soil subsidence, loess liquefaction and foundation cracking in red soil areas, resulting in casualties and economic losses. Research on the seismic response characteristics of soft soil mainly focuses on two aspects: the existence of soft soil in the form of interlayers and the presence of soft soil sites. [PERSON] et al. [2; 3; 4] studied the influence of soft interlayers on the surface acceleration peak, response spectrum characteristic period and platform value by establishing models of soft interlayers with different positions and thicknesses. The results showed that the surface acceleration peak and response spectrum platform value were inversely proportional tothe buried depth of the soft interlayers, while the response spectrum characteristic period was directly proportional to the buried depth of the soft interlayers. When the weak layer is located at the bottom of the special layer, the amplification factor is less than 1, indicating that the weak layer has an isolation effect. [PERSON] [5] used the equivalent linearization method to investigate the influence of the dynamic parameters of silted soil on the characteristic period and platform value of the response spectrum. The results showed that the characteristic period is inversely proportional to the ratio of the dynamic shear modulus, and this change trend slows with increasing input seismic intensity. The characteristic period is directly proportional to the change in input seismic intensity and inversely proportional to the change in shear-wave velocity and is not sensitive to changes in the damping ratio. The platform value is directly proportional to the change in the dynamic shear modulus ratio and shear-wave velocity and inversely proportional to the change in the damping ratio. The platform values of strong seismic motions are higher than those of moderate seismic motions, and under the same input strength conditions, the platform values change relatively smoothly with shear-wave velocity. [PERSON] et al. [6] studied the effect of the loading waveform under drainage conditions on the dynamic characteristics of soft soil and found that under a certain number of cyclic loading times, the axial strain rate of the sample under the sine wave loading waveform is greater than that under the triangular or square loading waveform. [PERSON] et al. [7] studied the dynamic characteristics of soft soil in the Pearl River Delta under cyclic loading of variable confining pressure and found that the cumulative axial strain and normalized damping ratio decreased with increasing cyclic confining pressure, and the maximum pore pressure and minimum pore pressure both increased with increasing cyclic confining pressure. There are many slopes in the loess area, combined with basic landforms such as loess plateaus, beams, hills, etc., which have an impact on the stability of the site in the loess area. [PERSON] [8] studied the seismic characteristics of loess valley type sites and found that as the input seismic intensity increases, the seismic motion at each monitoring point of the bedrock and loess valley type sites also increases. [PERSON] et al.