Abstract Upheaval buckling may occur for subsea pipelines laid on the seabed with topographic step imperfection under high temperature. In order to predict the post buckling behaviour of upheaval buckling, a finite element model of ABAQUS is proposed to simulate upheaval buckling for surface laid subsea pipelines with step imperfection. Firstly, a new method to introduce a step imperfection from an originally flat seabed is presented. Then, the finite element model of ABAQUS proposed in this paper is verified through the analytical results. The results obtained by FEA and analytical method have a good agreement. The influence of temperature difference, model length and step height on configuration and post buckling behaviour is investigated in detail. Our results show that rigid seabed assumption is reasonable in this study. The model length of the pipeline must be larger than the feed-in length. Otherwise, displacement amplitude, maximum stress and axial thermal expansion will be underestimated. For larger step height, displacement amplitude and maximum stress are larger at lower temperature difference due to the initial deflection induced by step imperfection of seabed, however, they become smaller at high enough temperature difference. The influence of step height and thickness of the pipe on the critical buckling force can be fitted well by a simple formula. The critical buckling force is barely affected by the axial friction coefficient between pipe and seabed.

中文翻译：

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具有地形台阶缺陷的海底管道隆起屈曲数值研究

摘要 海底管道铺设在具有地形台阶缺陷的海床上，在高温下可能发生巨屈曲。为了预测起伏屈曲的后屈曲行为，提出了一种ABAQUS有限元模型来模拟具有台阶缺陷的表面铺设海底管道的起伏屈曲。首先，提出了一种从原本平坦的海床上引入台阶缺陷的新方法。然后，通过解析结果验证了本文提出的ABAQUS有限元模型。有限元分析法得到的结果与分析方法有很好的一致性。详细研究了温差、模型长度和台阶高度对配置和后屈曲行为的影响。我们的结果表明，刚性海床假设在本研究中是合理的。管道的模型长度必须大于进料长度。否则，将低估位移幅度、最大应力和轴向热膨胀。对于较大的台阶高度，由于海床台阶缺陷引起的初始挠度，位移幅度和最大应力在较低温差下较大，但在足够高的温差下变小。台阶高度和管子厚度对临界屈曲力的影响可以用一个简单的公式很好地拟合。临界屈曲力几乎不受管道与海床轴向摩擦系数的影响。由于海床台阶缺陷引起的初始偏转，位移幅度和最大应力在较低温差下较大，但在足够高的温差下变小。台阶高度和管子厚度对临界屈曲力的影响可以用一个简单的公式很好地拟合。临界屈曲力几乎不受管道与海床轴向摩擦系数的影响。由于海床台阶缺陷引起的初始偏转，位移幅度和最大应力在较低温差下较大，但在足够高的温差下变小。台阶高度和管子厚度对临界屈曲力的影响可以用一个简单的公式很好地拟合。临界屈曲力几乎不受管道与海床轴向摩擦系数的影响。