## 7 Conclusions  
A large number of natural gas pipelines of different types and diameters are laid in the gas-coal overlapping area of the Ordos Basin. When a buried pipeline is within the influence range of the coal seam mining subsidence area, the movement and deformation of the surface overburden rock can easily lead to the deformation and failure of the buried pipeline, thus affecting the safe production of natural gas. According to this experimental study, the strain and maximum deformation position of a natural gas pipeline under loading are located at the middle of the pipeline. According to this, the maximum deformation and the most vulnerable position of a natural gas pipeline passing through the mining subsidence area can be preliminarily judged, and then the corresponding remedial and protection measures can be taken. Thus, the results of this study have a certain guiding role for the protection of natural gas pipelines. We drew the following conclusions:  
1. With the help of the test system, a local incremental load was applied to a natural gas pipeline with a diameter of 48 mm. It was found that the strain at the top and bottom of the pipeline increased with the increase in the load. The top of the pipeline was compressed, and the bottom was tensioned; the stress state at the top and bottom was opposite. Under the same load, the strain of the pipeline increased gradually from the end to the loaded position, and the increase in the strain at the top of the pipeline was significantly greater than that at the bottom.
2. With the help of the test system to monitor the stress of the pipeline end under the load, it was found that the load applied in the middle of the pipeline had a quadratic nonlinear positive correlation with the stress load at the end, and with the increase in the applied load, the stress load at the end of the pipeline exceeded the applied load.
3. With the help of the test system to monitor the deflection change of the pipeline under a load, it was found that with a gradual increase in the applied load, the overall deformation of the pipeline evolved from a flat-bottom shape to the funnel shape and finally to a triangular shape; plastic failure occurred when the pipeline became triangular. According to the experimental analysis, the deformation and strain distribution law of the pipeline under loading and the functional relationship between the end of the pipeline and the stress on the area in the subsidence area were determined. These results can provide a reference for performance parameter design, field protection measures, and pipeline layout of buried natural gas pipelines in gas-coal overlapping areas.  
Data collation, J.R.; experimental design, funding acquisition, W.W.; experiments and writing--original draft, F.W.; writing--review, X.L.; mechanical analysis, C.Z. All authors have read and agreed to the published version of the manuscript.  
This research was supported by the National Key R&D Program of China (52174109), the Program for Science and Technology Innovation Talents in Universities of Henan Province (23 HASITI011), and the Henan Province Key Research and Development Project (241111320800).  
The original results presented in the study are included in the article material; further inquiries can be directed to the corresponding author.  
The authors are grateful to the assigned editors and anonymous reviewers for their enthusiastic help and valuable comments, which have greatly improved this paper.  
Author [PERSON] was employed by the company China Energy Investment Group. 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.