Stress characteristics of double-row glass fiber-reinforced plastic pipe culvert with sand and optimization of load reduction parameters under adverse conditions

In this study, the stress and deformation rules of the double-row fiber-reinforced plastic sand pipes under the two loading methods of single-pipe and double-pipe loading were discussed. First, the indoor full-scale test was used to analyze the single-tube pipe top loading. The 90° measurement point of the loaded pipe and the 270° measurement point of the adjacent pipe were the most unfavorable positions for the stress of the pipeline. Through investigating the influence of cover soil height, load level, and compaction on the mechanical index of the most unfavorable load-bearing measuring point of the pipeline, the height of the overburden is found to be the most significant factor affecting the double-pipe stress system. Second, the numerical calculation model of the stress of the double-row pipeline was established to analyze the stress and deformation of the pipe culvert when the spacing of the double pipe was changed. The results indicated the critical spacing equivalent to the stress of the single pipe was 2.5D. Finally, the numerical method was also used to optimize the parameter of the geogrid at the top of the pipe in the most unfavorable stress state of the double pipe with 550-mm pipe spacing and double-loaded mode.