# Design of Conical Foundations with Increased Bearing Capacity in Areas of Undermined Soils
## 3 Results  
According to the data given in Table 4, the theoretical value determined by Formula (4) was that \(z_{\text{max}}\) was 18.3 mm, while observations during model tests in a volume-expandable stand at horizontal tensile deformation \(\varepsilon=9\) mm showed that the distance between cracks is about 9-10 mm and crack opening is about 0.5-1 mm. When transferred to real dimensions of soil displacement, these cracks are equivalent to a distance step of 2-4 m and an opening width of 32-44 mm. With a deformation of 3 mm, microcracks were detected in the equivalent soil at intervals of 10-20 mm, some of which increased to 0.8-1.5 mm with further expansion of the box. The frequency of crack opening was higher at the surface and decreased with depth. A comparison of the settlement of conical and column foundations under load demonstrated a clear advantage in favor of the first type, since as the settlement raises to 6 mm, the bearing area increases by 1.22 times when the aperture angle of the conical model is 90\({}^{\circ}\) (Figure 13a). And after applying a load of 0.15 kN, the isolated shallow founda  
Figure 12: Numerical modeling results of an isolated shallow foundation under 0.15 kN load with a horizontal soil displacement of 3 mm in the extendable stand: (**a**) deformed mesh; (**b**) displacement vectors; (**c**) total displacement; (**d**) vertical displacement; (**e**) horizontal displacement. tion completely loses its load-bearing capacity. With horizontal soil displacement, the maximum load-bearing capacity of an isolated shallow foundation is limited to 0.15 kN, while for conical foundation models it is much higher due to an increase in the foundation support area. Figure 13: Results of laboratory studies on load–settlement monitoring: (**a**)—conical model with aperture angle 90\({}^{\circ}\); (**b**)—conical model with aperture angle 80\({}^{\circ}\); 1, 2—curves obtained for isolated shallow foundation for horizontal tensile strains \(\varepsilon=0,3\) mm/m; 3, 4, 5, 6—curves obtained for conical foundation for horizontal tensile strains \(\varepsilon=0,3,6\) and 9 mm/m. Conical foundations with an aperture angle 90\({}^{\circ}\) showed superiority over the conical model of 80\({}^{\circ}\) aperture model and isolated shallow foundation. Settlement under a load of 0.2 kN without horizontal soil displacement reached 11 mm for conical foundations with an opening angle of 80\({}^{\circ}\) (Figure 13b), while for models with an aperture angle of 90\({}^{\circ}\) it did not exceed 9 mm. The presence of a horizontal displacement of up to 9 mm increased the soil settlement by 4 mm. Isolated shallow foundation models lost their bearing capacity after 0.14 kN. The results of the laboratory testing for the loading-settlement interaction of conical and isolated shallow models of foundations are presented in Table 4.  
Field test results were obtained for conical and isolated shallow foundations, observed before and after recorded horizontal movement at the experimental site of the Kostenko mine (Figure 14). The settlement under a load of 100 kN was 8.25 mm for conical foundations, with an aperture angle of 90\({}^{\circ}\) and 9.62 mm for foundations with an aperture angle of 80\({}^{\circ}\) (Table 5).