Abstract: In order to solve the problem that the application of large diameter FRP pipe is limited by subgrade elevation and top filling height, the mechanical properties, culvert cost and engineering cost of small diameter double row FRP pipe culvert and large diameter single row FRP pipe culvert are compared and analyzed, and the replacement of small diameter double row pipe is demonstrated. The results show that: under the same subgrade design elevation, small diameter double-row pipe culverts can obtain more sufficient soil cover height, which significantly weakens the stress effect of external loads on the culvert. The alternative scheme can ensure the service of the pipeline under low stress state, which is beneficial to prolong the service life of the pipeline. Under the same working conditions, the stress values of single-row pipe and double-row pipe meet the requirements of their compressive strength and tensile strength, and the culvert with small diameter and double-row pipe has better safety reserve. The production cost and engineering cost of the culvert with small diameter and double-row pipe can be saved by 1172.39 yuan per meter, and the economic benefit can be achieved significant.

Key words: FRP sandwich pipe, small diameter double row pipe, covering soil thickness, alternative feasibility