To study the collapse of imperfect subsea pipelines, a 2D high-order nonlinear model is developed. In this model, the large deformation of the pipes is considered by retaining the high-order nonlinear terms of strain. In addition, the J2 plastic flow theory is adopted to describe the elastoplastic constitutive relations of material. The quasi-static process of collapse is analyzed by the increment method. For each load step, the equations based on the principle of virtual work are presented and solved by the discrete Newton's method. Furthermore, finite element simulations and full-scale experiments were preformed to validate the results of the model. Research on the major influencing factors of collapse pressure, including D/t, material type and initial ovality, is also presented.
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