## 5 Discussion
The correctness of Equations (4) and (5) can be seen:  
\[f_{Si+Cl,1-I}\div f_{Si+Cl,1-XII}>f_{Si+Cl,1}; \tag{4}\]  
\[f_{Si+Cl,2-I}\div f_{Si+Cl,2-XII}>f_{Si+Cl,2}. \tag{5}\]  
For a given moisture content of a soil sample, there was a trend towards an increase in the proportion of the silt and clay fraction in the granulometric composition with an increase in the initially applied pressure of the pneumatic launcher to start the bar projectile movement. The trend in the behavior of the sample occurred as the impact velocity of the bar projectile increased, which can be represented by Equations (6)-(9):  
\[w_{1}=0\%\rightarrow \begin{pmatrix}f_{Si+Cl,1-I}<f_{Si+Cl,1-II}<f_{Si+Cl,1- III}\\ f_{Si+Cl,2-I}<f_{Si+Cl,2-III}<f_{Si+Cl,2-III}\end{pmatrix} ; \tag{6}\]  
\[w_{2}=5\%\rightarrow \begin{pmatrix}f_{Si+Cl,1-IV}<f_{Si+Cl,1-V}<f_{Si+Cl,1- V}\\ f_{Si+Cl,2-IV}<f_{Si+Cl,2-V}<f_{Si+Cl,2-VI}\end{pmatrix} ; \tag{7}\]  
\[w_{3}=10\%\rightarrow \begin{pmatrix}f_{Si+Cl,1-VII}<f_{Si+Cl,1-VIII}<f_{Si+ Cl,1-IX}\\ f_{Si+Cl,2-VII}<f_{Si+Cl,2-VIII}<f_{Si+Cl,2-IX}\end{pmatrix} ; \tag{8}\]  
\[w_{4}=15\%\rightarrow \begin{pmatrix}f_{Si+Cl,1-X}<f_{Si+Cl,1-XI}<f_{Si+Cl,1- XI}\\ f_{Si+Cl,2-X}<f_{Si+Cl,2-XI}<f_{Si+Cl,2-XI}<f_{Si+Cl,2-XIII}\end{pmatrix} . \tag{9}\]  
As the moisture content of the soil sample increased, there was no simple relationship of change in the proportion of the silt and clay fraction in the granulometric composition (only an increasing relationship or only a decreasing relationship). For the moisture content of soil samples, \(w_{1}\) and \(w_{2}\) (values below the optimum moisture content \(w_{opt}\)) for a given initial pressure of the pneumatic launcher (given impact velocity), a tendency towards an increase in the value of the silt and clay fraction was apparent (there was no significant effect of water on the test results). The higher the moisture content of the soil sample (in particular for \(w_{3}\) and \(w_{4}\) values above the optimum moisture content \(w_{opt}\)), the stronger the trend of a decreasing value of the silt and clay fraction in the granulometric composition of the silty sand sample could be seen. There was a clear, dynamic response of the water filling the soil pores--the water gave the sample some characteristics of an elastic material and \"damped\" the dynamic impact of the bar projectile impact. This interaction had the effect of reducing the phenomenon of destruction of the soil skeleton by grain fracture, which can be represented in Equations (10)-(12). \[ \begin{pmatrix}p_{1}=1.2\text{ bar}\\ v_{1}=12.76\text{ m/}S\end{pmatrix} \rightarrow \begin{pmatrix}if\ w_{1}<w_{2}<w_{ opt,1}\text{ then }f_{Si+Cl,1-I}<f_{Si+Cl,1-IV}\\ (if\ w_{2}<w_{opt,1}<w_{3}<w_{4}\text{ then }f_{Si+Cl,1-IV}>f_{Si+Cl,1-VII}>f_{Si+Cl,1-X} )\\ (if\ w_{1}<w_{2}<w_{opt,2}\text{ then }f_{Si+Cl,2-I}<f_{Si+Cl,2-IV}\\ (if\ w_{2}<w_{opt,2}<w_{3}<w_{4}\text{ then }f_{Si+Cl,2-IV}>f_{Si+Cl,2-VII}>f_{Si+Cl,2-X} )\end{pmatrix} ; \tag{10}\]  
\[ \begin{pmatrix}p_{2}=1.8\text{ bar}\\ v_{2}=17.69\text{ m/}S\end{pmatrix} \rightarrow \begin{pmatrix}if\ w_{2}<w_{ opt,1}\text{ then }f_{Si+Cl,1-I}<f_{Si+Cl,1-VII}\\ (if\ w_{2}<w_{opt,1}<w_{3}<w_{4}\text{ then }f_{Si+Cl,1-VII}>f_{Si+Cl,1-XI} )\\ (if\ w_{1}<w_{2}<w_{opt,2}\text{ then }f_{Si+Cl,2-VI}<f_{Si+Cl,2-V}\\ (if\ w_{2}<w_{opt,2}<w_{3}<w_{4}\text{ then }f_{Si+Cl,2-V}>f_{Si+Cl,2-VII}>f_{Si+Cl,2-XI} )\end{pmatrix} ; \tag{11}\]\[ \begin{pmatrix}p_{3}&=&2.4\;\text{bar}\\ v_{3}&=&21.32\;\text{m}/\text{S}\end{pmatrix} \rightarrow \begin{pmatrix}if\;w_{1}<w_{2}<w_{ opt,1}\;then\;f_{Si+C1,1-III}<f_{Si+C1,1-VI}\\ \text{if}\;w_{2}<w_{opt,1}<w_{3}<u_{4}\;then\;f_{Si+C1,1-VI}>f_{Si+C1,1-IX}>f_{Si+C1,1- XII}\\ \text{if}\;w_{1}<w_{2}<w_{opt,2}\;then\;f_{Si+C1,2-III}<f_{Si+C1,2-VI}\\ \text{if}\;w_{2}<w_{opt,2}<w_{3}<u_{4}\;then\;f_{Si+C1,2-VI}>f_{Si+C1,2-IX}>f_{Si+C1,2-XI}\\ \end{pmatrix} \text{.}