## 4 Results and Discussion  
### Ultimate Compressive Capacity  
Figure 6 shows the load-settlement curves of double piles with 6D pile spacing without continuously solidified parts and with continuously solidified parts at 2D burial depth. From Figure 6, it can be seen that the bearing capacity of the SCS group pile foundation with a continuously solidified part is significantly improved. Since the load-settlement curves of the SCS group pile foundation did not show peaks, this paper adopted the double-curve fitting method [34; 35; 36; 37] to determine the ultimate bearing capacity of the piles. Figure 7 illustrates the process of determining the ultimate bearing capacity of model piles using this method. Figure 5: Design of the test scheme (unit: mm). (**a**) Without a continuously solidified part; (**b**) continuously solidified 4D pile spacing; and (**c**) continuously solidified 6D pile spacing. Figure 6: Load–settlement curve of the A-S18 pile and the P-D6-S18 pile. The load-settlement curve was fitted as:  
\[Q=\frac{s}{a+bs}\]  
where \(Q\) represents the pile top load value (unit: \(N\)), \(s\) represents the settlement value (unit: mm), and \(a\) and \(b\) represent the double-curve fitting parameters. After fitting, the ultimate bearing capacity of each group of model piles and the corresponding settlements were determined and shown in Table 2.  
As shown in Table 2, the ultimate compressive bearing capacity of each group of SCS group pile foundation is increased by four to nine times compared with that of the traditional group pile foundations, and the settlement of the pile tops at the time of reaching the ultimate compressive bearing capacity is also increased by about once. Under the premise that the integrity of the pile body and the stiffness of the solidified can be guaranteed, the installation of the continuously solidified part can help to significantly improve the vertical bearing capacity of the group pile foundation. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Pile Diameter**} & \multirow{2}{*}{**Test Number**} & **Ultimate** & \multirow{2}{*}{**Settlement** (mm)**} & **Ultimate** \\  & & **Compressive** (N)** & & **Compressive** \\ \hline \multirow{8}{*}{4D} & A-S12 & 183.2 & 7.06 & 1.0 \\ \cline{2-5}  & P-D6-S12 & 1210.1 & 14.74 & 6.6 \\ \cline{2-5}  & P-D18-S12 & 1101.7 & 16.59 & 6.0 \\ \cline{2-5}  & P-D30-S12 & 1384.4 & 15.47 & 7.6 \\ \cline{2-5}  & P-D42-S12 & 1337.7 & 12.24 & 7.3 \\ \cline{2-5}  & P-D54-S12 & 1850.9 & 15.53 & 10.1 \\ \hline \multirow{8}{*}{6D} & A-S18 & 321.3 & 8.71 & 1.0 \\ \cline{2-5}  & P-D6-S18 & 1555.2 & 16.21 & 5.0 \\ \cline{1-1} \cline{2-5}  & P-D18-S18 & 1557.1 & 16.29 & 5.0 \\ \cline{1-1} \cline{2-5}  & P-D30-S18 & 1756.2 & 18.37 & 5.6 \\ \cline{1-1} \cline{2-5}  & P-D42-S18 & 1889.2 & 19.79 & 6.0 \\ \cline{1-1} \cline{2-5}  & P-D54-S18 & 2509.6 & 14.93 & 8.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Ultimate compressive capacity and settlement of each group of model piles. Figure 7: The ultimate bearing capacity of the model pile was determined using the hyperbolic fitting method. In order to study the influence of a continuously solidified position on the bearing characteristics of the SCS group pile foundation, the load-settlement relationship of each group was plotted according to the test data. The numerical points of the ultimate bearing capacity of each group obtained using the hyperbolic method are highlighted and labeled in Figure 8.  
The relationship between the ultimate bearing capacity of each group of SCS group pile foundations and solidified burial depths is shown in Figure 9. As illustrated in Figures 8 and 9, the solidified burial depth affects the bearing capacity of the SCS group pile foundation. The model pile with a solidified upper surface burial depth of 6D had the lowest ultimate bearing capacity, followed by the model pile with a solidified upper surface burial depth of 2D.