## 5 Discussion  
The protective silicate shell of the new design is technologically different from the previously known methods of ground improvement, but it was also more accurate from the distribution of sodium silicate solution around and beneath the pile, as well as posed better suffusion- and water-impermeable insolation. The results of in situ static loading tests showed that the bearing capacity of the piles casted in protective silicate shells was exceeded by 2.5 times compared to the bearing capacity of the ordinary bored piles without preliminary wetting of the soils and 3.2 times after prolonged soil wetting. Analyzing the loading-settlement curves from six experimental zones in Figure 14, we can conclude that the loading-settlement curve obtained by numerical modeling had a close relationship with the average experimental curve obtained when testing six SLT with the protective shell. The graph also showed the polynomial characteristics of the obtained curves, with correlation coefficients of 0.999 for both curves. The polynomial curve comprised possible transversely increasing and decreasing extreme pikes of the dependence. In this case, the least squares fit was performed using the following formula:  
\[y=b+c_{1}x+c_{2}x^{2}+c_{3}x^{3}+\ldots+c_{n}x^{n}, \tag{10}\]  
where \(b\), \(c_{1}\)... \(c_{n}\) are polynomial function constants. Using polynomial equations, the settlement was predicted with a further loading pile, both for the experimental and calculated curves. The effectiveness of the proposed technology for the installation of bored piles in a protective and load-bearing shell was given in comparison with the construction technology of the ordinary pile. As it was determined, the bearing capacity of piles with a protective and bearing shell exceeded the bearing capacity of the ordinary pile by 2.5 times on average. According to this ratio, the required number of ordinary piles and the substitutive amount of piles with a protective and load-bearing shell might be found. Thus, five ordinary piles would respond to the same bearing capacity as two piles with a protective shell. In our example, \(645\cdot 5=3225\approx 1646\cdot 2=3292\) kN. The total cost of the materials and labor costs for the \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Parameter Name**} & \multirow{2}{*}{**Designation**} & \multirow{2}{*}{**Unit**} & \multicolumn{4}{c}{**Values for**} \\ \cline{3-6}  & & & **Soil** & \multicolumn{2}{c}{**Silicate**} & **Pile** \\ \hline Calculation model & - & - & Coulomb–Mohr & Linear-elastic & Linear-elastic \\ \hline Soil behavior type & - & - & drained & undrained & undrained \\ \hline Specific gravity of dry soil/dry unit weight & Ydry & kN/m\({}^{3}\) & 18.0 & 21.6 & 24.0 \\ \hline Specific gravity of saturated soil/saturated unit weight & Ywet & kN/m\({}^{3}\) & 20.0 & 23.2 & 24.0 \\ \hline Soil permeability in horizontal direction & kx & m/day & \(1\times 10^{-5}\) & \(1\times 10^{-9}\) & - \\ \hline Soil permeability in vertical direction & ky & m/day & \(1\times 10^{-5}\) & \(1\times 10^{-9}\) & - \\ \hline Deformation modulus for soil/elastic modulus for pile or shell & E & kN/m\({}^{2}\) & 10.8 & 530,000 & \(3\times 10^{7}\) \\ \hline Poisson’s ratio & v & - & 0.35 & 0.25 & 0.1 \\ \hline Cohesion & c & kN/m\({}^{2}\) & 21 & 27.3 & - \\ \hline Angle of internal friction & \(\varphi\) & grad. & 26 & 27 & - \\ \hline Dilatancy angle & \(\psi\) & grad. & 0 & 0 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Accepted simulation parameters. construction of the piles is presented in Table 6, as well as the economic efficiency, based on modern prices for the installation of bored piles in Kazakhstan. The advantages of the construction of a bored pile with a protective shell, built by impregnating the near-pile soils with silicate solution, can be considered its environmental friendliness, irreversible corrosion resistance, water resistance, and optimal distribution of strength along the entire length of the shell and in the near-pile zone.