摘要
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。
Using the P-y curve to simulate the interaction behavior between SCR and soil, the paper studies the riser-soil interaction response and performs fatigue analysis of SCR at TDZ under cyclic motions. The sag-bend and flow-line of SCR are modeled by flexible beam with large curvature and elastic foundation beam. SCR involves complex nonlinear dynamic behaviors, especially at the Touchdown Zone （TDZ） where the riser starts to touch the seabed. It is difficult to numerically simulate the riser-soil interaction due to the assocaited uncertainty in seabed model. A FORTRAN programming code modeling the riser-soil interaction is introduced into CABLE3D, and then CABLE3D RSI is obtained. The riser-soil interaction response and the global dynamic analysis are performed using the developed program, and the structural fatigue assessment is carried out by S-N approach. Results indicate： 1） SCR has been perturbed by 10 regular sinusoidal cycles and the responses show a number of features such as suction force mobilization, gradual increasing penetration depth, and gradually reducing mobilization of soil resistance at maximum penetration. The nonlinear riser-soil model accords with the actual seabed properties compared with linear and rigid seabed; 2） The comparative analysis shows that some points between TDP and the maximum embedment point are the key locations where maximum fatigue damage occurs. Parameters such as shear strength, suction factor play a vital role for the dynamic riser-soil interaction and fatigue behavior at TDZ.
出处
《工程力学》
EI
CSCD
北大核心
2016年第3期248-256,共9页
Engineering Mechanics
基金
国家自然科学基金项目(51109185
51179179)
浙江省自然科学基金项目(Z15E090001
Y15D060005)
浙江省科技厅公益项目(2013C33065)
关键词
钢悬链线立管
管土作用响应
非线性
触地区
疲劳分析
steel catenary riser
riser-soil interaction response
nonlinear
touchdown zone
fatigue analysis
