The pipe-soil interactions at shoulders can significantly affect the vortex-induced vibrations (VIV) of free-spanning pipes in the subsea. In this paper, the seabed soil reacting force on the pipe is directly calculat...The pipe-soil interactions at shoulders can significantly affect the vortex-induced vibrations (VIV) of free-spanning pipes in the subsea. In this paper, the seabed soil reacting force on the pipe is directly calculated with a nonlinear hysteretic soil model. For the VIV in the middle span, a classic van der Pol wake oscillator is adopted. Based on the Euler-Bernoulli beam theory, the vibration equations of the pipe are obtained which are different in the middle span and at the two end shoulders. The static configuration of the pipe is firstly calculated and then the VIV is simulated.The present model is validated with the comparisons of VIV experiment, pipe-soil interaction experiment and the simulation results of VIV of free-spanning pipes in which the seabed soil is modelled with spring-dashpots. With the present model, the influence of seabed soil on the VIV of a free-spanning pipe is analyzed. The parametric studies show that when the seabed soil has a larger suction area, the pipe vibrates with smaller bending stresses and is safer.While with the increase of the shear strength of the seabed soil, the bending stresses increase and the pipe faces more danger.展开更多
为了揭示海底自由悬跨管道纯顺流向涡激振动特征,本文考虑跨肩处管-土耦合作用,结合Euler-Bernoulli梁理论和Van der pol方程,构建了海底自由悬跨管道纯顺流向涡激振动的预报模型,分析了海底泥面土体不排水抗剪强度、土体强度梯度、跨...为了揭示海底自由悬跨管道纯顺流向涡激振动特征,本文考虑跨肩处管-土耦合作用,结合Euler-Bernoulli梁理论和Van der pol方程,构建了海底自由悬跨管道纯顺流向涡激振动的预报模型,分析了海底泥面土体不排水抗剪强度、土体强度梯度、跨肩处管道嵌入土体深度和土体塑性指数等对纯顺流向涡激振动的影响规律。研究结果表明:泥面土体不排水抗剪强度越弱、土体强度梯度越小、管道嵌入土体越浅、塑性指数越大,纯顺流向涡激振动越容易发生。展开更多
海底悬跨管道涡激振动问题十分复杂,需考虑流-管-土多场耦合效应。本文将悬跨管线简化为Euler-Bernoulli梁,两端跨肩管-土作用与线弹性弹簧和扭转弹簧近似,采用Van der pol方程描述旋涡脱落的尾迹特性。利用模态正交性对流-耦合控制方...海底悬跨管道涡激振动问题十分复杂,需考虑流-管-土多场耦合效应。本文将悬跨管线简化为Euler-Bernoulli梁,两端跨肩管-土作用与线弹性弹簧和扭转弹簧近似,采用Van der pol方程描述旋涡脱落的尾迹特性。利用模态正交性对流-耦合控制方程进行解耦,采用龙格-库塔法进行数值求解,重点分析非对称边界对海底管道涡激振动特性的影响。计算结果表明:非对称边界条件对最大响应幅值影响不大;约束条件越强烈,模态激发越难,响应频率越高。展开更多
基金This study was financially supported by the National Natural Science Foundation of China(Grant No.51679167)the Natural Science Foundation of Shandong Province of China(Grant No.ZR2018MEE032)。
文摘The pipe-soil interactions at shoulders can significantly affect the vortex-induced vibrations (VIV) of free-spanning pipes in the subsea. In this paper, the seabed soil reacting force on the pipe is directly calculated with a nonlinear hysteretic soil model. For the VIV in the middle span, a classic van der Pol wake oscillator is adopted. Based on the Euler-Bernoulli beam theory, the vibration equations of the pipe are obtained which are different in the middle span and at the two end shoulders. The static configuration of the pipe is firstly calculated and then the VIV is simulated.The present model is validated with the comparisons of VIV experiment, pipe-soil interaction experiment and the simulation results of VIV of free-spanning pipes in which the seabed soil is modelled with spring-dashpots. With the present model, the influence of seabed soil on the VIV of a free-spanning pipe is analyzed. The parametric studies show that when the seabed soil has a larger suction area, the pipe vibrates with smaller bending stresses and is safer.While with the increase of the shear strength of the seabed soil, the bending stresses increase and the pipe faces more danger.
文摘为了揭示海底自由悬跨管道纯顺流向涡激振动特征,本文考虑跨肩处管-土耦合作用,结合Euler-Bernoulli梁理论和Van der pol方程,构建了海底自由悬跨管道纯顺流向涡激振动的预报模型,分析了海底泥面土体不排水抗剪强度、土体强度梯度、跨肩处管道嵌入土体深度和土体塑性指数等对纯顺流向涡激振动的影响规律。研究结果表明:泥面土体不排水抗剪强度越弱、土体强度梯度越小、管道嵌入土体越浅、塑性指数越大,纯顺流向涡激振动越容易发生。
文摘海底悬跨管道涡激振动问题十分复杂,需考虑流-管-土多场耦合效应。本文将悬跨管线简化为Euler-Bernoulli梁,两端跨肩管-土作用与线弹性弹簧和扭转弹簧近似,采用Van der pol方程描述旋涡脱落的尾迹特性。利用模态正交性对流-耦合控制方程进行解耦,采用龙格-库塔法进行数值求解,重点分析非对称边界对海底管道涡激振动特性的影响。计算结果表明:非对称边界条件对最大响应幅值影响不大;约束条件越强烈,模态激发越难,响应频率越高。