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基于P-y曲线建立非线性管-土相互作用模型,分别运用大挠度曲线梁和弹性地基梁单元模拟钢悬链线立管(Steel Catenary Riser,SCR)的悬垂段和流线段,研究周期运动下管-土相互作用响应和SCR触地区的疲劳分析。SCR具有复杂的非线性动态行为,特别是触地点区域,由于海床模型的不确定性,一直是数值模拟的难点。通过Fortran编写子程序嵌入CABLE3D,开发得到包括非线性管-土作用模型的新程序CABLE3D RSI,围绕SCR与海床相互作用响应和立管的整体动力分析等内容展开研究:根据时域内的动力响应,运用S-N曲线法得到触地点区域的疲劳损伤分布情况,研究有关参数对疲劳损伤的影响。结果表明:1)周期载荷作用下,立管在海床上形成的沟槽逐渐发展,相比于线弹性和刚性海床非线性海床分布力更加符合工程实际:2)海床刚度模型、土剪切强度以及吸力因子都对立管触地区的疲劳损伤具有重要影响。
Based on the Py curve, a nonlinear pipe-soil interaction model was established. The suspended and flowing sections of the Steel Catenary Riser (SCR) were simulated by the large deflection curve beam and the elastic foundation beam respectively. The effects of periodic motion Tube - soil interaction response and fatigue analysis of SCR contact area. SCR has complex nonlinear dynamic behavior, especially the touch point area, which has been a difficult point of numerical simulation due to the uncertainty of the seabed model. The CABLE3D RSI, a new program including nonlinear pipe-soil interaction model, was developed by embedding CABLE3D in Fortran program. The interaction between SCR and seabed and the overall dynamic analysis of riser were studied. According to the dynamic response in the time domain , The distribution of fatigue damage in the contact area was obtained by using the SN curve method and the influence of relevant parameters on the fatigue damage was studied. The results show that: 1) The groove formed on the sea floor by the riser gradually develops under cyclic loading, which is more in line with engineering practice than that of linear elastic and rigid sea floor; 2) The model of sea floor stiffness, Shear strength and suction factor all play an important role in the fatigue damage in the contact zone of risers.