## 3 Verification of Small-Scale Test with FEM
### Small-Scale Finite Element Model  
A numerical model was created using off-the-shelf software (PLAXIS 3D Ultimate) [13] based on the finite element method to compare with the results of the physical test. For a dependable comparison, the finite element model was established as per the conditions reported in the study mentioned earlier (Figure 3).  
To acquire more converged outcomes, the element sizes belonging to the finite element model should be as small as possible [14; 15; 16]. For that purpose, among the mesh densities varying from very coarse to very fine offered by the software, the fine mesh density was employed in this study. [PERSON] et al. [17] indicated that using a very fine mesh density significantly increased the analysis duration, whereas it did not provide a significant improvement in the results compared to a fine mesh density with a refinement around the structural element. Therefore, it was thought that the fine mesh density with a mesh refinement around the rigid foundation was a reasonable approach when considering the lesser complexity of the problem investigated in this paper. The finite element model with a fine mesh density is illustrated in Figure 3. Also, to avoid boundary effects, the boundaries of the finite element model were kept at a sufficient distance of 5D for all directions, where D refers to the diameter of the foundation [18]. In the finite element  
Figure 2: Schematic view of the physical test setup with measuring instruments [12].  
simulations performed within the scope of this study, the material characteristics belonging to soft and rigid foundation presented in detail in Table 5 were considered.  
As observed in Figure 4, the finite element model established successfully demonstrated the results of the physical test reported by [PERSON] et al. [12]. Hence, based on this finding, it can be stated that the characteristics of soft clay and rigid foundation employed in the simulations are reasonable and sufficient for this study.  
Figure 4: Comparison of the results of small-scale physical test and finite element method [12].  
Figure 3: The finite element model with a fine mesh density (not to scale).  
\begin{table}
\begin{tabular}{l l l} \hline  & **Parameters** & **Value** \\ \hline \multirow{8}{*}{Soft clay} & Material model & Mohr–Coulomb \\  & Drainage type & Undrained \\  & Saturated unit weight, \(\rho_{\text{sat}}\) (kN/m\({}^{3}\)) & 19.0 \\  & Dry unit weight, \(\rho_{\text{dry}}\) (kN/m\({}^{3}\)) & 18.0 \\  & [PERSON]’s modulus, E\({}_{\text{clay}}\) (kN/m\({}^{2}\)) & 13,000 \\  & Cohesion, c (kN/m\({}^{2}\)) & 45 \\  & [PERSON]’s ratio, \(\
u\) (-) & 0.35 \\  & Internal friction angle, \(\phi\) (\({}^{\circ}\)) & 0 \\  & Dilatancy angle, \(\psi\) (\({}^{\circ}\)) & 0 \\ \hline \multirow{4}{*}{Rigid foundation} & Material model & Linear elastic \\  & Drainage type & Non-porous \\  & Unit weight, \(\rho\) (kN/m\({}^{3}\)) & 24.0 \\  & [PERSON]’s modulus, E (kN/m\({}^{2}\)) & 32 \(\times\) 10\({}^{6}\) \\  & [PERSON]’s ratio, \(\
u\) (-) & 0.25 \\ \hline \end{tabular}
\end{table}
Table 5: Characteristics of soft clay and rigid foundation considered in simulations.