# Design of Conical Foundations with Increased Bearing Capacity in Areas of Undermined Soils
## 1 Introduction
[PERSON] et al. proposed a one-piece cone-shaped hollow flexible reinforced concrete foundation (CHFRF) for a mountain wind turbine [22; 23]. A rubber layer was placed beneath the CHFRF to increase the foundation flexibility to resist cyclic and dynamic loadings and to increase the bearing capacity. [PERSON] et al. used machine learning regression approach for the analysis of bearing capacity of conical foundations in clayey soils to understand the sensitivity of bearing capacity, including failure mechanisms, cone apex angle, embedded depth to height ratio, strength gradient ratio, anisotropic ratio and cone shape [24]. According to [PERSON] et al. modeling the bearing capacity factor F was strongly affected by cone apex angle 100%, while strength gradient ratio, embedded depth ratio, and anisotropic ratio were a lower ranking of influence within the relative importance index at 91.52%, 90.73%, and 17.19%, respectively. The highest bearing capacity of a conical foundation was determined at 0 immersion level of the cone, that is, when the base of the cone does not sink below ground surface level, while the angle at the apex of the cone of 30-60\({}^{\circ}\) had a greater load-bearing capacity [24]. Although [PERSON] et al. [25] were studying the dependence of vertical bearing capacity factors for the conical footing on base roughness, the angle of internal friction of soil and different apex angles, by performing two-dimensional lower and upper bound finite element limit analysis (FELA), determined that load bearing capacity increased with an increase in the apex angle of the conical footing from 30\({}^{\circ}\) to 180\({}^{\circ}\). Theoretical analysis has been also carried out by [PERSON] and [PERSON] [26], [PERSON] and [PERSON] [27]. [PERSON] and [PERSON], using the numerical method of characteristics in the FIELD program, calculated the destructive loads to determine the bearing capacity using an axisymmetric problem and derived the general shear failure mechanism of the conical model [28]. Since the previous authors limited themselves to only theoretical analysis and modeling, it was decided to test the conical foundation model in the laboratory and at the test site for the purpose of further research for use in civil engineering as the foundations of buildings and structures. A test method has been developed that simulates horizontal displacement of the soil in the laboratory conditions. Full-scale tests were limited by the ability to regulate soil movements and deformations and were carried out on real observations. The main goal of the research was to study effectively responsive stable foundations of a conical shape that are resistant to horizontal tensile deformations of soil masses in undermined areas, in order to prevent emergency situations and, as a result, reduce construction costs. Based on the results of computer modeling by previous authors, \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Groups of Territories** & **Relative Horizontal Deformation \(\epsilon\), mm/m** & **Inclination I, mm/m** & **Radius of Curvature R, km** \\ \hline
1 & \(12\geq\epsilon>8\) & \(20\geq\epsilon>10\) & \(1\leq\text{R}<3\) \\
2 & \(8\geq\epsilon>5\) & \(10\geq\epsilon>7\) & \(3\leq\text{R}<7\) \\
3 & \(5\geq\epsilon>3\) & \(7\geq\epsilon>5\) & \(7\leq\text{R}<12\) \\
4 & \(3\geq\epsilon>0\) & \(5\geq\epsilon>0\) & \(12\leq\text{R}<20\) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Groups of territories in undermined areas. as well as preliminary laboratory tests with samples, conical models with opening angles of 90\({}^{\circ}\) and 80\({}^{\circ}\) were selected as the model of the conical foundation under study.