## 5 Conclusions  
In this paper, the mechanical mechanism and settlement performance of a non-contact pile-raft foundation were analyzed using the 3D finite element method, and the effect of the composite foundation of CFG pile on controlling the settlement of a high-rise building was studied. To overcome the difficulty of poor convergence caused by the large number of piles, an equivalent simulation method for the reinforcement zone was proposed. Based on the calculation and analysis in this study, the following conclusions can be stated:  
(1) After setting a cushion between the pile and the raft plate, the internal force of the raft can be adjusted effectively and the extremum of its moment can be reduced. However, when the strength and stiffness of the pile are high, the entire settlement of the raft can be increased because of the large deformation at the top and bottom of the pile.  
(2) The settlement can be controlled well using a CFG pile with relatively low strength to reinforce the foundation. The axial force and the bending moment of the raft of the CFG pile were clearly lower than those of the bored pile in the foundation.  
(3) When the number of piles was large, the reinforcement zone (including the soil and the pile) can be regarded as an anisotropic elastoplastic material. Once the integral strength and stiffness parameters of the reinforcement zone were given properly, the settlement and bending moment of the raft obtained using the integral equivalent simulation method were more or less consistent with those obtained using the embedded pile simulation method.  
(4) The equivalent simulation method of the reinforced zone is suitable for buildings on a large scale, with a large number of structural units and complex synergetic interactions between soil and structure. It is an effective and practical method to quickly evaluate the settlement control effect of foundation treatment schemes. It should be emphasized that the selection of equivalent parameters in the reinforcement zone depends on experience and trial calculations, and needs to be systematically studied in the future.  
All the authors were involved collaboratively in the paper drafting and review. In particular, [PERSON] and [PERSON] conceived and designed the research; [PERSON] took care of the FE modeling and parametric studies, while [PERSON] implemented the simplified analytical model; [PERSON] and [PERSON] performed the numerical analyses; [PERSON] and [PERSON] analyzed the data and prepared the manuscript; [PERSON] optimized the numerical model. [PERSON] supervised the overall project.  
This research was funded by the Shanxi Province Natural Science Foundation (201701D121068), the Research Plan of Shanxi Province Department of Transportation in China (2016-1-7), the China Postdoctoral Science Foundation (2016M591044), the National Basic Research Program of China (973 Program, 2014 CB047001), and the Innovation and Entrepreneurship Training Program for Undergraduate in Shanxi Province, China (201810108034).  
Figure 19: Distribution of moment in the center section of the raft of the high-rise buildings.  
**Acknowledgments:** The authors thank [PERSON], from the China Institute of Building Standard Design and Research, for his support and help in numerical modeling.  
**Conflicts of Interest:** The authors declare no conflicts of interest.