# Investigation of Geotechnical Seismic Isolation Systems Based on Recycled Tire Rubber-Sand Mixtures
## 3 Results and Discussions
### Ground Motions Selection
\begin{table}
\begin{tabular}{c c c c c} \hline \hline Shear Wave Velocity of Clay & & & 200 \\ Soil Layer (m/s) & & & \\ \hline Profile Depth (m) & 20 & 19 & 18 & 17 \\ \hline Isolation (m) & 0 & 1 & 2 & 3 \\ \hline Shear Wave Velocity of & - & 152.14 & 152.14 & 152.14 \\ Isolation Layer (m/s) & - & 9.91 & 9.91 & 9.91 \\ \hline Initial Damping Ratio (\%) & - & 2.461 & 2.424 & 2.387 \\ \hline Natural Frequency (Hz) & 2.5 & 2.461 & 2.424 & 0.4189 \\ \hline Natural Period (s) & 0.4 & 0.4063 & 0.4126 & 0.4189 \\ \hline \multirow{3}{*}{Earthquake} & \multirow{3}{*}{EL (Hz)} & \%10-100 kPa & \multirow{3}{*}{Damping Ratio (\%)} & \%10-100 kPa & \%10-100 kPa & \%10-100 kPa \\  & & 1 m Amp. & 2 m Amp. & 2 Amp. & 3 m Amp. \\  & & & & Ratio (Hz) & \\ \hline ChiChi & 3.702 & 3.212 & \(-\)13.24\% & 3.199 & \(-\)13.59\% & 3.179 & \(-\)14.13\% \\ \hline Coyote & 4.056 & 3.567 & \(-\)12.06\% & 3.554 & \(-\)12.38\% & 3.534 & \(-\)12.87\% \\ \hline Imp. Valley & 3.873 & 3.383 & \(-\)12.65\% & 3.364 & \(-\)13.14\% & 3.343 & \(-\)13.68\% \\ \hline Kocaeli & 4.200 & 3.745 & \(-\)10.83\% & 3.770 & \(-\)10.24\% & 3.790 & \(-\)9.76\% \\ \hline \multicolumn{3}{c}{Mean Value} & \multicolumn{3}{c}{\(\mathbf{-12.19\%}\)} & \multicolumn{3}{c}{\(\mathbf{-12.34\%}\)} & \multicolumn{3}{c}{\(\mathbf{-12.61\%}\)} \\ \hline \hline \end{tabular}
\end{table} 
Table 10: Table of dominant frequencies based on the measured Fourier amplitude ratio for the isolation layer composed of sand containing 10% rubber content (\(\sigma_{0}\) = 100 kPa). Figure 16: Fourier amplitude ratio for the ChiChi, Coyote, Imperial Valley, and Kocaeli earthquakes with the isolation layer composed of sand containing 10% rubber content and subjected to a confining pressure of 100 kPa. The Fourier amplitude ratio for the isolation layer containing 5% granular rubber and subjected to a confining pressure of 100 kPa, applied at thicknesses of 1, 2, and 3 m is shown in Figure 18, with a summary of these results provided in Table 12. \begin{table}
\begin{tabular}{c c c c c} \hline \hline Shear Wave Velocity of Clay & & & 200 \\ Soil Layer (m/s) & & & \\ \hline Profile Depth (m) & 20 & 19 & 18 & 17 \\ \hline Isolation (m) & 0 & 1 & 2 & 3 \\ \hline Shear Wave Velocity of & - & 120.61 & 120.61 & 120.61 \\ Isolation Layer (m/s) & - & 4.07 & 4.07 & 4.07 \\ \hline Initial Damping Ratio (\%) & - & 4.07 & 4.07 & 4.07 \\ \hline Natural Frequency (Hz) & 2.5 & 2.42 & 2.346 & 2.275 \\ \hline Natural Period (s) & 0.4 & 0.4132 & 0.4263 & 0.4395 \\ \hline \multirow{2}{*}{Earthquake} & \multirow{2}{*}{EL (Hz)} & \%10-50 kPa 1 m Amp. Ratio (\%) & Damping Ratio (\%) & \%10-50 kPa 3 m Amp. Ratio (\%) & Damping Ratio (\%) \\ \hline ChiChi & 3.702 & 3.217 & \(-\)13.10\% & 3.220 & \(-\)13.02\% & 3.232 & \(-\)12.70\% \\ \hline Coyote & 4.056 & 3.574 & \(-\)11.88\% & 3.580 & \(-\)11.74\% & 3.603 & \(-\)11.17\% \\ \hline Imp. Valley & 3.873 & 3.389 & \(-\)12.50\% & 3.388 & \(-\)12.52\% & 3.403 & \(-\)12.14\% \\ \hline Kocaeli & 4.200 & 3.753 & \(-\)10.64\% & 3.808 & \(-\)9.33\% & 3.899 & \(-\)7.17\% \\ \hline \multicolumn{3}{c}{Mean Value} & \multicolumn{3}{c}{\(\mathbf{-12.03\%}\)} & \multicolumn{3}{c}{\(\mathbf{-11.65\%}\)} & \multicolumn{3}{c}{\(\mathbf{-10.79\%}\)} \\ \hline \hline \end{tabular}
\end{table} 
Table 11: Table of dominant frequencies based on the measured Fourier amplitude ratio for the isolation layer composed of sand containing 10% rubber content (\(\sigma_{0}\) = 50 kPa). Figure 17: Fourier amplitude ratio for the ChiChi, Coyote, Imperial Valley, and Kocaeli earthquakes with the isolation layer composed of sand containing 10% rubber content and subjected to a confining pressure of 50 kPa.