Research on generalized optimization identification method for finite element model of directly buried heating pipelines with small folded angle reinforcement structure

The finite element numerical simulation is the main method to analyse the mechanical characteristics and stress distribution of the folded angle of the directly buried pipelines. However, the deviation between its simulation results and measured data is usually large, and it cannot correctly predict the maximum stress value of the folded angle structure. This paper focuses on the small folded angle reinforcement structure of directly buried pipelines, systematically analyses the error sources of finite element numerical simulation, and proposes a new staged generalized optimization identification method to sequentially determine the optimal boundary conditions and key model parameters of the folded angle reinforcement structure. The calculation case shows that simulating non-uniform stress can provide the best boundary stress distribution. The elastic modulus of pipeline and soil is the key parameter for finite element simulation. For the small folded angle reinforcement structure (pipe diameter DN700, angle 12°), the optimal values of the elastic modulus of pipeline and soil are 19.94×104MPa and 11 MPa, respectively.