# Design of Conical Foundations with Increased Bearing Capacity in Areas of Undermined Soils
## 4 Discussion  
The presented study differs in the research method from [25; 26; 27; 28], in that laboratory tests were performed on a three-dimensional expandable testing stand with simulating horizontal soil displacement. Moreover, conical foundations are proposed to be buried in the ground not to their full height, as in [25]. Solid conical foundation models were considered here, the operation of which differs from hollow cones in [23]. In this work, it also proposes a ball joint to eliminate horizontal forces in the upper part of the structure located above the base beam. Conical foundations were proposed to be used for the construction of buildings and structures in the form of a series of cones and not a single solid foundation to support a wind turbine, as was proposed by [24; 25]. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Foundation Model Type**} & \multirow{2}{*}{**Horizontal Tensile Strains of Soil, mm/m**} & \multicolumn{3}{c}{**Settlement under Load, mm**} \\ \cline{3-5}  & & **0.1 kN** & **0.15 kN** & **0.2 kN** \\ \hline \multirow{5}{*}{Conical foundation with an aperture angle of 90\({}^{\circ}\)} & 0 & 0.75 & 2.65 & 9.54 \\  & 3 & 1.02 & 3.30 & 11.24 \\  & 6 & 1.32 & 3.90 & 12.19 \\  & 9 & 1.55 & 4.50 & 13.51 \\ \hline \multirow{5}{*}{Conical foundation with an aperture angle of 80\({}^{\circ}\)} & 0 & 0.80 & 3.40 & 11.51 \\  & 3 & 1.03 & 4.19 & 13.48 \\ \cline{1-1}  & 6 & 1.30 & 4.80 & 15.50 \\ \cline{1-1}  & 9 & 1.60 & 5.70 & 16.54 \\ \cline{1-1}  & 0 & 1.30 & 7.25 & - \\ \cline{1-1} Isolated shallow foundation & 3 & 1.50 & 11.44 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Results of the numerical modeling for loading-settlement interaction. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Foundation Model Type**} & \multirow{2}{*}{**Horizontal Tensile Strains of Soil, mm/m**} & \multicolumn{3}{c}{**Settlement under Load, mm**} \\ \cline{3-5}  & & **50 kN** & **75 kN** & **100 kN** \\ \hline \multirow{2}{*}{Conical foundation with an aperture angle of 90\({}^{\circ}\)} & 0 & 3.21 & 5.72 & 8.25 \\  & 2.6 & 3.45 & 6.61 & 9.62 \\ \hline \multirow{2}{*}{Conical foundation with an aperture angle of 80\({}^{\circ}\)} & 0 & 3.25 & 6.08 & 9.21 \\  & 2.6 & 3.50 & 6.85 & 10.50 \\ \hline \multirow{2}{*}{Isolated shallow foundation} & 0 & 3.70 & 8.4 & - \\  & 2.6 & 4.10 & 10.0 & - \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Field test results. In the works of [PERSON] et al. [23], [PERSON] et al. [24], [PERSON] et al. [25], and [PERSON] and [PERSON] [26], conical foundations were designed with the base immersed to or below the ground level. In this work, considering the requirement of increased responsibility for civil engineering, installation depth of a conical foundation in the ground is recommended with partial immersion that provides a safety margin compared to an isolated shallow foundation. In this case, the load-bearing capacity increases in direct proportion to the insertion depth of conical block. Experimental studies of the present research have demonstrated that in the elastic stage of deformation, the bearing capacity and settlement for conical and isolated shallow models are the same (Figure 15). With further loading of the foundation models, the penetration capacity of the conical shape of the foundation decreases due to an increase in the area of contact with the soil thickness. And for foundations with an isolated shallow cross-section, the support area is the same in height. For the same reason, according to the obtained load-settlement graphs, the maximum bearing capacity of conical foundations was not achieved. Laboratory tests are confirmed by the results of the numerical method with identical initial parameters of the soil and foundation models (Figure 15). Isolated shallow foundations lost their bearing capacity after 0.15 kN, while conical foundations continued to bear the load even under conditions of horizontal soil movement.