## 5 Discussion  
In order to clearly summarize the results of the tests in the laser particle size analyzer (results from Section 4) and to show the visible trends in the change of granulometric composition of the samples of silty sand subjected to dynamic impact in the SHPB test, Table 5 is prepared for both soil samples with initial content of silty and clay fraction \(f_{Si+CI,1}=15.14\%\) and \(f_{Si+CI,2}=20.48\%\). The table summarizes the results taking into account the initial moisture content of the soil sample and the pneumatic launcher pressure of the SHPB loading bar projectile. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{2}{c}{**Reference**} & \multicolumn{4}{c}{**Moisture Content of the Silty Sand Sample \(\mathbf{w}_{i}\)**} \\ \cline{2-6} \multicolumn{2}{c}{**Sample \(f_{Si+CI}\)**} & \multicolumn{2}{c}{\(\mathbf{w_{1}=0\%}\)} & \(\mathbf{w_{2}=5\%}\) & \(\mathbf{w_{3}=10\%}\) & \(\mathbf{w_{4}=15\%}\) \\ \hline \multirow{4}{*}{\(f_{Si+CI,1}=15.14\%\)} & \multirow{4}{*}{\(f_{Si+CI,1:4}=16.64\%\)} & \multirow{4}{*}{\(f_{Si+CI,1:4}=16.64\%\)} & \multirow{4}{*}{\(f_{Si+CI,1:4}=18.17\%\)} & \multirow{4}{*}{\(f_{Si+CI,1:4}=17.15\%\)} & \multirow{4}{*}{\(f_{Si+CI,1:4}=16.66\%\)} \\  & & & & & \\ \cline{2-6}  & & \(p_{2}=1.8\) bar & \multirow{2}{*}{\(f_{Si+CI,1:4}=23.58\%\)} & \multirow{2}{*}{\(f_{Si+CI,1:4}=23.58\%\)} & \multirow{2}{*}{\(f_{Si+CI,1:4}=23.97\%\)} & \multirow{2}{*}{\(f_{Si+CI,1:4}=22.08\%\)} & \multirow{2}{*}{\(f_{Si+CI,1:4}=19.92\%\)} \\  & & & & & \\ \cline{2-6}  & & \(p_{3}=2.4\) bar & \multirow{2}{*}{\(f_{Si+CI,1:4}=25.10\%\)} & \multirow{2}{*}{\(f_{Si+CI,1:4}=26.22\%\)} & \multirow{2}{*}{\(f_{Si+CI,1:4}=22.96\%\)} & \multirow{2}{*}{\(f_{Si+CI,1:4}=21.24\%\)} \\  & & \(p_{3}=21.32\) m/s & & & & \\ \hline \multirow{4}{*}{\(f_{Si+CI,2}=20.48\%\)} & \multirow{4}{*}{\(f_{Si+CI,2:4}=24.80\%\)} & \multirow{4}{*}{\(f_{Si+CI,2:4}=28.71\%\)} & \multirow{4}{*}{\(f_{Si+CI,2:4}=21.18\%\)} & \multirow{4}{*}{\(f_{Si+CI,2:4}=20.84\%\)} \\  & & & & & \\ \cline{2-6}  & & \(p_{2}=1.8\) bar & \multirow{2}{*}{\(f_{Si+CI,2:4}=29.17\%\)} & \multirow{2}{*}{\(f_{Si+CI,2:4}=31.00\%\)} & \multirow{2}{*}{\(f_{Si+CI,2:4}=24.99\%\)} & \multirow{2}{*}{\(f_{Si+CI,2:4}=24.76\%\)} \\  & & & & & \\ \cline{2-6}  & & \(p_{3}=21.32\) m/s & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Summary of \(f_{Si+CI}\) silty and clay fraction values obtained in the laser particle size analyzer for the different configurations of the variable variants of the silty sand sample after dynamic impact in the SHPB test. Figure 13: Summary graphs of grain size curves for silty sand with silt and clay fraction \(f_{Si+CI,2}=20.48\%\) for sample variants I–XIII (12 sample variants subjected to dynamic impact in SHPB and reference sample without dynamic impact) in variable configurations: (**a**) \(w_{1}\) and \(p_{1}\) (\(v_{1}\))–\(p_{2}\) (\(v_{2}\))–\(p_{3}\) (\(v_{3}\)), (**b**) \(w_{2}\) and \(p_{1}\) (\(v_{1}\))–\(p_{2}\) (\(v_{2}\))–\(p_{3}\) (\(v_{3}\)), (**c**) \(w_{3}\) and \(p_{1}\) (\(v_{1}\))–\(p_{2}\) (\(v_{2}\))–\(p_{3}\) (\(v_{3}\)), (**d**) \(w_{4}\) and \(p_{1}\) (\(v_{1}\))–\(p_{2}\) (\(v_{2}\))–\(p_{3}\) (\(v_{3}\)). Based on the data presented in Table 5, it is possible to note the behavioral trends and direction of trends in the dynamic characteristics of the silty sand:  
Each silty sand sample used on the SHPB test stand achieved a higher proportion of fine fractions (silt and clay) in its granulometric composition after the test compared to the reference sample. Each dynamic impact with the bar projectile resulted in an increase in the value of the silt and clay fraction \(f_{Si+Cl}\)--there was a phenomenon of destruction of the soil skeleton through grain breaking and an increase in the percentage of smaller-diameter grains.