Theoretical investigation on the upheaval thermal buckling of a lined subsea pipeline

Abstract

In this study, according to the nonlinear von-Kármán assumption and Euler-Bernoulli beam theory, a mathematical model is proposed to simulate upheaval buckling of lined subsea pipelines, which considers the difference in material properties of the liner and outer pipe. A closed-form solution is derived. The analytical solutions are verified by comparing them with the results in the literature. The influence of Young's modulus and the thermal expansion coefficient of the liner on the post-buckling response is analysed. The post-buckling behaviour of the outer pipe and liner are compared. The effect of the ratio of the liner's thickness to the outer pipe's thickness on the post-buckling response of the lined subsea pipeline is analysed in detail. The results show that the liner must be included in the analysis of upheaval thermal buckling. The post-buckling behaviour of both the liner and outer pipe are affected significantly by the thermal expansion coefficient of the liner. The displacement amplitude, axial compressive force, maximum bending moment and maximum stress all increase with increasing ratio of the liner's thickness to the outer pipe's thickness.