## 3 Optimization of Reclamation Works in the Aquatic Direction
### Inclination Optimization for Slopes Functioning as Beaches  
The inclination of a slope functioning as a beach should be shaped with allowance for the stability conditions, as well as for the safety and comfort concerns. Its basic function is to provide access and gentle descent to the bathing area (lido) and to facilitate leisure activities. In order to verify whether beach stability is possible for underwater slopes having an inclination greater than the recommended 1:60-1:30, the stability was calculated for several inclination ratios: 1:30, 1:25, 1:20, and 1:15. Figures 4 and 5 show horizontal stresses for clay and for coarse sand, respectively. The analyzed increase in the inclination ratio did not influence the results of the simulations. From the perspective of slope stability, calculations of the Coulomb-Mohr potential are more important. The determination of the medium's plasticization zones was performed based on the Coulomb-Mohr potential. The negative value of the potential defines the areas where the area is stable. Where the potential is positive, the shear strength has been exceeded. Calculations are shown for both types of soil in Figures 6 and 7. The potential sign was not observed to reverse in any area, which suggests good stability conditions for both underwater and above-water slopes, for both media. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline
**Soil** & \(\gamma_{s}\) & \(n\) & \(\rho\) & \(I_{L}\) & \(I_{D}\) & \(\gamma\) & \(\gamma^{\prime}\) & \(\phi^{\prime}\) & \(c\prime\) & \(E\) & \(\
u\) & \(\gamma_{s}\) & \(n\) \\ \hline - & kN/m3 & - & kg/m3 & - & - & kN/m3 & kN/m3 & \({}^{\circ}\) & kPa & MPa & - & - & kN/m3 \\ Clay & 27.2 & 0.5 & 1390 & 0.4 & - & 13.6 & 8.7 & 9.5 & 32.5 & 8.0 & 0.37 & 27.2 & 0.5 \\ Sand & 26.5 & 0.3 & 1890 & - & 0.5 & 18.5 & 11.7 & 35.0 & 0 & 80.0 & 0.25 & 26.5 & 0.3 \\ \hline \end{tabular} \(\gamma_{s}\)—specific weight of the soil skeleton, \(n\)—porosity, \(\rho\)—soil bulk density, \(I_{l}\)—liquidity index, \(I_{D}\)—density index, \(\gamma\)—specific weight of the soil, \(\gamma^{\prime}\)—effective weight; \(\phi^{\prime}\)—internal angle of friction, \(c^{\prime}\)—cubesion, \(E\)—Young’s modulus, \(\
u\)—Poisson ratio.  
\end{table} 
Table 1: Parameters of the media. Figure 3: The modeled area with the final computational mesh. Figure 4: Horizontal stresses for the sand-type subsoil, for underwater slope inclinations of: (**a**) 1:30, (**b**) 1:25, (**c**) 1:20, (**d**) 1:15 (negative values indicate compressive stresses in Pa, and positive values—tensile stresses in Pa). Figure 5: Cont. Figure 5: Horizontal stresses for the clay-type subsoil, for underwater slope inclinations of: (**a**) 1:30, (**b**) 1:25, (**c**) 1:20, (**d**) 1:15 (negative values indicate compressive stresses in Pa, and positive values—tensile stresses in Pa). Figure 6: Coulomb–Mohr potential for the sand-type subsoil, for underwater slope inclinations of: (**a**) 1:30, (**b**) 1:25, (**c**) 1:20, (**d**) 1:15 (negative values indicate compressive stresses in Pa, and positive values—tensile stresses in Pa). In addition, Figure 8 shows shear stresses obtained from the calculated directions of main stresses for the greatest assumed inclinations of the underwater slope. The results suggest that the stability of the underwater slope is more important for the stability of the entire area, as the region beneath it is subjected to the highest shear stresses (the regions with a positive stress sign in Figure 8). The slope stability analyses indicate that increased underwater slope inclination does not affect the stability of the slope system forming the beach and may by increased to as much as 1:15. Therefore, the recommended inclination of 1:30 does not seem to result from the soil strength conditions but from the expected comfort of the users. An additional note should be made that an inclination of 1:15 is an optimal solution in the case wherein the excavation depth renders an underwater slope with an inclination of 1:30 or less impossible.