Influence of FRP arrestors on the dynamic collapse and implosion of underwater pipelines

The dynamic collapse of pipelines in deep water can create pressure pulses that affect the performance of surrounding structures. In this study, the pipe implosion process was analysed using the Lagrangian–Eulerian method. The numerical model was calibrated using the experimental data, and the responses of the pipelines and surrounding fluid during pipeline collapse and buckle propagation were obtained. The fluid–structure interaction mechanism of the composite arrestors attenuating the pressure pulse was investigated. The simulation results showed that the implosion of a pipeline was a transient high-energy dynamic event. The fluid surrounding the pipe rushed towards the pipe surface at a high velocity during implosion and dynamic buckle propagation, which resulted in a spatial change in pressure distribution. Notably, the unidirectional fibre reinforced polymer (FRP) arrestor had a positive effect on reducing the peak pressure of the pulse wave. Furthermore, the effects of different arrestor spacings and materials on pipe buckling and implosion pressure were discussed, and the design of FRP arrestors was optimised.