Abstract: The coupling effect between the pipe and soil was considered during the process of sinking the pipe into the trench. Based on the theory of elastic foundation beams, a stress analysis model for the pipeline under the back sinking pipe into the trench was constructed using the deflection curve equation and deformation coordination conditions. To verify the accuracy of the analytical model, a finite element model considering the plastic constitutive relationship of soil was established with Abaqus for comparative analysis. When the results of the standard model, analytical model, and finite element model were compared on parameters(length of the arch section, length of the suspended section, maximum stress, and bending moment of the pipeline), the errors between the analytical model and the finite element model were found to be 3.58%, 3.50%, 4.89%, and 3.52%, respectively. Meanwhile, the maximum error between the standard model and the finite element model was observed to reach 13.40%.The results showed that during the lowering of the pipeline into the trench, the maximum stress first occurred at the middle position of the immersed tube. After 80 m of excavation, it appeared at the end of the trench excavation. Before contact with the trench bottom was made, three stress concentration points were identified in the pipeline. After contact with the trench bottom was established, four stress concentration points were observed in the pipeline.This modeling method, based on the interaction mechanism, was demonstrated to more accurately characterize the mechanical response characteristics of the pipeline-soil system. From an engineering practice perspective, the model was confirmed to significantly improve the accuracy of pipeline system mechanical analysis. It is considered to hold important engineering application value for ensuring the structural integrity and operational safety of long-distance pipelines.

Key words: reverse immersed tube, stress analysis, analytical model, numerical validation