Abstract: The Large diameter of FRPM pipe is limited due to the problems such as pipe production, transportation and the elevation of highway culvert. In order to explore the feasibility of using small diameter double pipes instead of large diameter FRPM pipe, the physical and mechanical characteristics and change rules of the double pipes under the condition of single pipe under load are analyzed by indoor simulation test. The experimental results show that there is an interaction between the deformation of the double pipes under the condition of loading single pipe, and the deformation of the pipes is imbalance. And, the weak area of the double pipes appears in the roof of loading pipe and the adjacent position of the double pipes. The result can be used as the safety control points and the actual engineering design basis of double pipes.

Key words: double of FRPM pipes, Indoor test, the state of force, imbalance