Analytical and numerical study on lateral buckling of imperfect subsea pipelines with nonlinear lateral pipe-soil interaction model

The nonlinear pipe-soil interaction model and the initial imperfections are predominantly factors that affect the lateral buckling behaviour of subsea pipelines with a high-temperature. In this study, mathematical models, taking these two factors into account, are proposed to simulate lateral buckling of subsea pipelines. Analytical solutions are derived from the assumption of rigid-plastic pipe-soil interaction, while numerical results are obtained when considering nonlinear pipe-soil interaction. The analytical and numerical results have an excellent agreement except for the negligible discrepancy in the pre-buckling state. The discrepancy is induced by the difference of mobilisation distance in rigid-plastic and elastic-plastic pipe-soil interaction models. After the analysis of snap-through phenomenon, the influence of breakout resistance, amplitude and half-wavelength of imperfection on the post-buckling behaviour is studied. Finally, the upper and lower bound critical temperature differences are discussed as well. The results show that the hysteresis cycle between pre-buckling and post-buckling states may appear under cyclic thermal loading. The snap-through phenomenon and the hysteresis cycle can take place more easily for large breakout resistance, small amplitude and large wavelength of imperfection. In the post-buckling state, the maximum stress uplifts with increasing breakout resistance or amplitude of imperfection, while it reduces with escalating wavelength of imperfection.