## 4 Results
### Q-S Curve Analysis
Thus, compared to planted piles without an isolated stone, planted piles with an isolated stone at the base can provide greater bearing capacity, and correspondingly, they also exhibit higher side friction resistance. Figure 6: Load-displacement curve. Figure 7 shows that the axial force distribution in the core pile derived from the simulation calculations closely matches that obtained from the model tests. Figure 7a displays the axial force distribution for a core pile without an isolated stone. It is evident that the axial force in the planted core pile decreases with depth, which can be attributed to the downward frictional resistance from the outer concrete acting to hinder the upward pull of the core pile. The axial force curve shows varying rates of decrease at different positions along the pile body. The slope of the axial force curve reflects the magnitude of frictional resistance. Within a 3 cm range from the pile head, the rate of decrease in the axial force curve is highest for the core pile head. This may be due to the greatest displacement difference between the core pile and the outer concrete at the pile head. As the depth increases, the displacement difference between the core pile and the outer concrete gradually decreases, and the internal frictional resistance between the core pile and the outer concrete also decreases and stabilizes. Therefore, the maximum internal frictional resistance for the planted pile occurs at the pile head. This indicates that the deformation of the planted core pile is approximately coordinated with that of the outer concrete. When the load is 6.4 N, the axial force in the lower section of the pile approaches zero, indicating that the end resistance of the core pile is nearly zero, with the load on the core pile primarily borne by side friction resistance. As the load increases, the side friction resistance becomes more pronounced, resulting in an increase in axial force along the pile \begin{table}
\begin{tabular}{c c c c} \hline
**Experiment** & **Pile Type** & **Ultimate Bearing** & **Pile Top** \\
**Number** & **Pile Type** & **Capacity** & **Displacement** \\  & & **(N)** & **(D)** \\ \hline
1 & Planted pile & 12.8 & 0.2 D (2 mm) \\
2 & Planted pile & 38.4 & 0.35 D (3.5 mm) \\ \hline \end{tabular}
\end{table} 
Table 4: Comparison and analysis of experimental results for piles with and without isolated stone. Figure 7: Core pile axial force diagram; they should be listed as: (**a**) axial force diagram of core pile for planted pile without an isolated stone and (**b**) axial force diagram of core pile for planted pile with an isolated stone. body, gradually generating axial force in the lower section. Under the applied load, the upper core pile is the first part to engage. As the load progressively transfers down the pile body, it also gradually disperses through the outer concrete of the core pile into the surrounding soil. This creates a dual-layer load diffusion pattern: The load spreads from the core pile to the outer concrete and from the outer concrete to the surrounding soil. Figure 7b shows the axial force distribution for the core pile of the planted pile with the isolated stone at the tip. The axial force distribution in the upper portion of the planted core pile resembles that of the planted pile without the isolated stone. Under the same upward pull load, the axial force of the core pile gradually decreases with increasing depth. At the same cross-section of the pile body, the larger the upward pull load, the greater the axial force. The slope of the axial force curve for the core pile reflects the magnitude of side friction resistance, which gradually decreases with depth, but suddenly increases within the range of the isolated stone. The significant internal friction resistance at the pile head within a 3 cm range can be attributed to the largest displacement occurring between the core pile and the outer concrete under external loading.