## 4 Conclusions  
In this paper, corrosion-thinning reinforced concrete pipe sections were simulated by manually grinding the concrete protective layer. Ultra-high-performance concrete (UHP-ECC) was used to repair the corroded pipe sections. The influence of different corrosion thicknesses, repair thicknesses, and interface forms on the bearing capacity of the repaired pipe sections was studied, employing the control variable method. By analyzing the crack development law, failure mode, and load-displacement curve of each pipe section, the following conclusions were drawn:  
1. Following pipeline thinning due to corrosion, the bearing capacity is reduced, the corrosion thickness increases, and the degree of structure deformation damage increases. When the corrosion depth reaches the thickness of the protective layer, the residual bearing capacity of the pipeline is reduced by 35%.
2. Regarding certain other parameters, with the increase in corrosion thickness, the degree of structural deformation of the existing pipeline increases, the coordinated deformation relationship between the lining layer and the existing pipeline becomes weaker, and the ultimate bearing capacity of the pipeline decreases. The pipeline should be repaired in a timely manner when the degree of corrosion is low, which can reduce the repair thickness to achieve a larger increase in the bearing capacity, thereby reducing the loss of the overflow section.
3. For the same corrosion and repair thickness, the bearing capacity of a pipeline with a plastic film after repair is lower than that of a pipeline with a naturally bonded interface. The bearing capacity of a pipe with interfacial nail implantation is higher than that of the naturally bonded interface and the improvement is more significant.
4. A bonding plastic film weakens the interfacial bonding between the lining layer and the existing pipeline. Under the action of an external load, the two cannot fully coordinate the deformation and the interface is more likely to peel off, resulting in a decrease in the bearing capacity of the overall structure. Interfacial nail implantation can effectively improve the interfacial bonding effect of the pipeline, so that the overall structure reaches a superimposed structure state under an external load, and the bearing performance of the pipeline is greatly improved. When the reinforced concrete pipeline is repaired using the spraying method, the coordinated deformation relationship between the lining layer and the existing pipeline can be improved by means of interfacial nail implantation, so as to reduce the repair thickness as much as possible and ensure the flow capacity of the pipeline.  
P.Z.: Writing-reviewing and data curation; C.G.: Methodology and editing; Q.W.: Integration and editing.; C.Z.: Investigation. All authors have read and agreed to the published version of the manuscript[PERSON]  
This paper is supported by Science and Technology Project of State Grid Corporation of China (No. 5200-202029144A-0-0-00).  
Not applicable.  
All data that support the findings of this study are available from the corresponding author upon reasonable request.  
The authors declare no conflict of interest.