# Dynamic Characterization of Cohesive Material Based on Wave Velocity Measurements
## 3 Results and Discussion
### The Effect of Stress Level  
In Table 2, the authors compiled the range of received S-wave and P-wave velocities after each consolidation stage. On the basis of Table 2, it can be concluded that the values of shear wave velocity obviously increase with applied pressure. At the same time, it is visible that the differences between the shear wave velocity values and each \(p^{\prime}\) amount to 20 to 30 \(\mathrm{m}\cdot\mathrm{s}^{-1}\). The values of compression wave velocity confirmed the earlier observation about the lack of dependence between \(\upsilon_{\text{P}}\) and stress level. The typical P-wave velocity of the tested material reached the value of 1400 to 1500 \(\mathrm{m}\cdot\mathrm{s}^{-1}\) for the peak-to-peak method and 1600 to 1700 \(\mathrm{m}\cdot\mathrm{s}^{-1}\) for the start-to-start method. \begin{table}
\begin{tabular}{c c c c} \multicolumn{4}{c}{(**a**)} \\ \hline
**Mean Effective Stress** & **S-Wave Velocity** & **P-Wave Velocity** & **Average Ratio of Seismic Waves Velocities** \\ \hline \(p^{\prime}\) (kPa) & \(\upsilon_{\text{S}}\) (\(\mathrm{m}\cdot\mathrm{s}^{-1}\)) & \(\upsilon_{\text{P}}\) (\(\mathrm{m}\cdot\mathrm{s}^{-1}\)) & \(\upsilon_{\text{P}}\)/\(\upsilon_{\text{S}}\) (-) \\
30 & 145–168 & 1518–1595 & 9.3 \\
120 & 195–222 & 1469–1579 & 7.0 \\
180 & 221–224 & 1508–1568 & 6.4 \\
240 & 240–264 & 1522–1593 & 5.9 \\
360 & 267–292 & 1486–1581 & 5.3 \\
410 & 296–314 & 1435–1588 & 5.0 \\ \hline \multicolumn{4}{c}{(**b**)} \\ \hline
**Mean Effective Stress** & **S-Wave Velocity** & **P-Wave Velocity** & **Average Ratio of Seismic Waves Velocities** \\ \hline \(p^{\prime}\) (kPa) & \(\upsilon_{\text{S}}\) (\(\mathrm{m}\cdot\mathrm{s}^{-1}\)) & \(\upsilon_{\text{P}}\) (\(\mathrm{m}\cdot\mathrm{s}^{-1}\)) & \(\upsilon_{\text{P}}\)/\(\upsilon_{\text{S}}\) (-) \\
180 & 224–260 & 1715–1759 & 6.8 \\
240 & 252–284 & 1734–1779 & 6.3 \\
360 & 281–319 & 1590–1609 & 4.7 \\
410 & 301–336 & 1588–1645 & 4.9 \\ \hline \end{tabular}
\end{table} 
Table 2: Seismic waves velocities for various mean effective stress levels. (**a**) Peak-to-peak method; (**b**) start-to-start method. Figure 12: Variation of [PERSON]’s modulus with frequency. (**a**) Peak-to-peak method; (**b**) start-to-start method. In Table 2, additionally, the average ratio list of seismic wave's velocities is enclosed. It is evident that the values of \(\upsilon_{P}\) are several times higher, when compared with \(\upsilon_{S}\). The \(\upsilon_{P}/\upsilon_{S}\) velocity ratio has the variation interval ranging from 5.0 to 9.3. The authors obtained larger values of P-wave velocity than is observed in certain positions in the literature. [PERSON] and [PERSON] [48], for example, reported the characteristic compression wave velocity as ranging from 1220 m\(\cdot\) s\({}^{-1}\) to 1370 m\(\cdot\) s\({}^{-1}\) for saturated clay, although the ratio \(\upsilon_{P}/\upsilon_{S}\) was in the range of 8.0 to 9.0, thus similar to those obtained by the authors. [PERSON] [49], on the other hand, in his study on Parameters That Influence Seismic Velocity mentions P-wave velocity for saturated clays as being in the range of 1100 to 2500 m\(\cdot\) s\({}^{-1}\). [PERSON] and [PERSON] [50] detailed typical speeds of longitudinal and transversal waves to a depth of 40 m. According to their research, compressive wave velocity for saturated soils may have values between 1500 and 1900 m\(\cdot\) s\({}^{-1}\). In Table 3, the results of the average dynamic Poisson's ratio computed for each applied mean effective stress is shown. \(\
u_{d}\) was determined on the basis of the relationship between S-wave and P-wave velocities (Equation (8)). The values of \(\
u_{d}\) seem to be consistent with the literature [4; 51; 52]. The authors described the values of this parameter in another publication [23], in which the results obtained for saturated clay were at the level of 0.40 to 0.50, which is similar to the value obtained during the current studies. It is interesting to note that there is no significant change in \(\upsilon_{d}\) regarding the pressure.