中文摘要：

海管铺设或者提升、下放时可能因应力过大而破坏,因此需建立数学分析模型进行施工方案设计。海管铺设和单点缓慢提升和下放过程可用两种控制微分方程求解,一种是二阶微分方程形式,另一种是三阶微分方程组形式,两者的适用范围目前尚不明确。两种微分方程与不同边界条件组合,并结合一个新的确定悬空管道长度的公式,形成三个分析模型。对这三个模型的数值求解表明：三阶微分方程组形式的控制方程能更准确的描述海管单点提放的整个过程,且与海洋管道有限元分析软件OrcaFlex的计算结果完全一致。

英文摘要：

The pipeline would be damaged during offshore pipe laying and lifting or lowering operation due to large stress,so the mathematical analysis model for these operations needs to be established for engineering design.There are usually two kinds of differential equations to solve the problem.One is of the second-order format and the other of the third-order format.The usage range of them is not determined so far.Three models are established with different boundary conditions combining differential equations and a new method to determine the length of suspending pipe.Numerical solution of these models shows that the differential equation of third-order format is better for modeling offshore pipe lifting or lowering procedure and is consistent completely with the results of the marine pipe finite element analysis software OrcaFlex.