# Comparative Study of the Seismic Response Characteristics of Three Special Soils
## 5 Calculation Results and Analysis  
### Analysis of the Calculation Results of a Uniform Single-Soil-Layer Profile  
In this paper, a uniform and single ideal soil section for each of the three special soils is used for the calculation model. Four ground motion time histories obtained by modulating the El Centro wave amplitude are used as input seismic waves, and the SOILQUAKE program is used to calculate and comparatively analyze the characteristics and seismic responses of the three special soils. Three typical areas of special soils are chosen [19]. The dynamic shear modulus ratio, damping ratio and shear-wave velocity within the range from the maximum to the minimum are employed, totaling seven groups of values that change sequentially and replace the corresponding values in Table 2 for the calculations. Figures 2 and 3 present group diagrams of the three special soil dynamic shear modulus ratios and damping ratios, and Table 9 provides a group list of the shear-wave velocities of the three special soils. Figure 2: Grouping curves of dynamic shear modulus ratio of three special soils. (**a**) Soft Soil; (**b**) Loess; (**c**) Laterite. Figure 4 depicts a schematic diagram of the calculated characteristic parameters of the design response spectrum for the three special soils under different input ground motion intensities. As shown in Figure 4, (1) the characteristic parameters of the three special soils are proportional to the input seismic intensity; that is, the greater the intensity is, the greater the characteristic period and platform value. (2) When the input ground motion intensity is constant, the characteristic periods of the design response spectra of the three special soils are inversely proportional to both the dynamic shear modulus ratio and the shear-wave velocity but are not sensitive to changes in the damping ratio; in terms of the platform values, the dynamic shear modulus ratio is directly proportional to the shear-wave velocity and inversely proportional to the damping ratio. To further compare and analyze the influences of the three special soils on the characteristic parameters of the design response spectrum, a fourth group comprising soft soil, loess and laterite (i.e., the averaged dynamic shear modulus ratio, damping ratio and shear-wave velocity) is selected in this paper. Figure 5 schematically compares the corresponding calculation results. Figure 3: Three kinds of special soil damping ratio grouping curves. (**a**) Soft Soil; (**b**) Loess; (**c**) Laterite. \begin{table}
\begin{tabular}{c c c c c c c c} \hline  & **One** & **Two** & **Three** & **Four** & **Five** & **Six** & **Seven** \\ \hline Soft Soil & 110 & 115 & 120 & 125 & 130 & 135 & 140 \\ Loess & 180 & 210 & 240 & 270 & 300 & 330 & 360 \\ Laterite & 220 & 240 & 260 & 280 & 300 & 320 & 340 \\ \hline \end{tabular}
\end{table} 
Table 9: Three kinds of special soil shear wave velocity grouping list (m/s). Figure 4: Schematic diagram of calculation results of characteristic parameters of design response spectra of three special soils under different input ground motion intensities. (**a**) Schematic diagrams of calculation results of dynamic shear modulus ratio; (**b**) Schematic diagram of damping ratios calculation results; (**c**) Schematic diagram of shear wave velocity calculation results. According to the comparison of the three special soil characteristic parameters in Figure 5, it is not difficult to determine the following: (1) Under an identical ground motion input, the characteristic period of soft soil is the largest, followed by that of laterite, while the characteristic period of loess is the smallest. Moreover, the characteristic periods of loess and laterite are relatively small, and the characteristic periods of both are identical, but they are quite different from (close to half of) that of soft soil. (2) When the input ground motion intensity is constant, the platform values of loess and laterite are relatively close, and both are higher than the platform value of soft soil.