## 5 Conclusions  
This study utilizes transparent soil technology to conduct non-intrusive model tests on planted piles and planted piles with isolated stones at the end under various tensile loading conditions. Furthermore, it performs a comparative analysis with a discrete-continuous coupled three-dimensional numerical model to evaluate the bearing capacity, load transfer mechanisms, and the interactions between the piles and the surrounding soil. The conclusions are as follows. 1. The upper load on the planted piles is mainly borne by the high-strength prestressed pipe core piles, which not only transmit the load downwards, but also disperse it through the concrete surrounding the pipes into the surrounding soil. In areas where isolated stone is present, the load diffuses from the outer concrete layer to the isolated stone and then into the surrounding soil, creating a three-layered diffusion pattern. This effectively transmits the upper load to a larger affected area than that of planted  
Figure 14: Affected range of the soil layer under the ultimate pullout load for planted pile; they should be listed as: (**a**) affected range of the soil layer for planted pile without an isolated stone and (**b**) affected range of the soil layer for planted pile with an isolated stone. piles without isolated stone, resulting in superior bearing capacity and doubling the ultimate pullout bearing capacity of the test piles. 2. The deformation of the planted piles is primarily controlled by the core piles, with the core and outer concrete layers deforming in a coordinated manner. The axial force in the core pile decreases with depth, and the vertical force in the outer concrete layer also decreases with depth. In planted piles with an isolated stone at the end, the axial force of the core pile and the vertical force in the outer concrete layer show a sudden decrease in the isolated stone region due to the larger contact area formed with the surrounding soil, which enhances the lateral frictional resistance in that area. 3. The distribution patterns of internal and external friction forces along the pile stem decrease gradually. The internal friction of the planted pile is approximately 1.47 times that of the external friction and about 0.8 times the ratio of the diameters of the planted pile and the core pile. The internal friction of planted piles with an isolated stone at the end is approximately 1.37 times that of the external friction. 4. The presence of the isolated stone enhances the soil-bearing capacity and also expands the area of stress distribution around the pile. Under ultimate loading conditions, the displacement field of the surrounding soil for planted piles without isolated stones is distributed in an \"inverted triangle,\" with a maximum width of 4.0 D at the pile top and about 2.0 D at the pile end. For planted piles with an isolated stone at the end, the displacement field of the surrounding soil exhibits a trapezoidal distribution that is wider at the bottom and narrower at the top, with the influenced area reaching 12.0 D vertically and 5.0 D horizontally at the pile end, and the maximum impact width of the soil at the pile top measuring 4.0 D. 5. Overall, the presence of isolated stones at the base of the pile can provide additional support, enhancing the load transfer pathways and the influence range of the surrounding soil. This indicates that the incorporation of isolated stones into the load-bearing system of the pile can not only mitigate the effects of the stones on the pile foundation, but also effectively enhance the overall load-bearing capacity of the pile. Conceptualization, Q.C., W.L. and H.L. ; methodology, Q.C., W.L. and H.L. ; software, H.L. and W.L. ; validation, X.G., J.Z. and S.S.; formal analysis, W.L., H.L. and X.G. ; investigation, Q.C., H.L., J.Z., S.S., X.G. and W.L. ; resources, Q.C., J.Z., X.G. and S.S.; data curation, W.L., H.L., X.G. and S.S.; writing--original draft preparation, W.L. and X.G. ; supervision, Q.C., X.G., J.Z. and S.S.; project administration, Q.C., X.G. and J.Z.