## 5 Conclusions  
This study aims to compare the load-bearing characteristics of traditional reinforced concrete uplift piles with composite-anchor piles. Enhanced field tests and numerical simulation methods were utilized to analyze the factors that influence the load-bearing capacity of composite-anchor piles. The results indicate that, when considering the same low reinforcement ratio (0.75%) and construction method, composite-anchor piles exhibit an equivalent load-bearing capacity as traditional piles. However, when the dry hole method is employed, the load-bearing capacity of composite-anchor piles increases by 18% compared to traditional piles.  
Furthermore, load test curves conducted on site demonstrate that the displacement curve of the pile top during the loading of composite-anchor piles exhibits a gradual change over time, indicating a more uniform stress transfer. An analysis of load-bearing capacity parameters obtained from a numerical simulation reveals that modifying the structure of the composite-anchor cable within the pile can effectively enhance the overall load-bearing capacity of the uplift pile. From an economic and environmental perspective, altering the structure of the internal anchor cable not only simplifies construction and reduces construction time, but also minimizes damage to the surrounding soil, ensuring soil stability.  
Based on comprehensive experimental and simulation results, it was observed that the load-bearing capacity of composite-anchor piles is closely linked to the frictional resistance at the interface of the composite-anchor cable inside the pile. However, current codes and standards lack a quantitative method to assess this type of internal interface frictional resistance. Therefore, this study proposes a specific method for calculating the load-bearing capacity and successfully applies it to projects conducted in the Fangshan area of Beijing. This promotes the future utilization and advancement of this type of pile.  
In the Fangshan area projects, replacing traditional piles with composite-anchor piles reduced steel consumption by 41.74% and lowered project costs by approximately 25.47%. The economic benefits were substantial. Additionally, utilizing the dry hole method for construction resolved issues such as tight project schedules, noise disturbances, and the environmental impact of mud. Therefore, composite-anchor piles also exhibit positive environmental benefits and warrant widespread promotion and application.  
Conceptualization, [PERSON] and [PERSON]; methodology, [PERSON]; formal analysis, [PERSON]; data curation, [PERSON]; writing--original draft preparation, [PERSON]; writing--review and editing, [PERSON] and [PERSON]; supervision, [PERSON] and Y.W. All authors have read and agreed to the published version of the manuscript.  
The study described in this paper was supported by the Talent Fund of Beijing Jiaotong University (2022 XKRC005).  
Not applicable.  
The data presented in this study are available upon request from the corresponding author. Due to the fact that the work in the study was carried out by different authors without a shared folder, and some data originated from actual engineering projects involving certain privacy concerns, these data are not publicly available.  
Author [PERSON] was employed by the company China Building Technique Group Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.