悬链线和大变形梁理论的J型铺设研究

Analysis of J lay installation of a steel catenary riser based on catenary and large deflection beam theory

为获得J型铺设解析方法,研究了深水钢悬链立管的J型铺设作业过程中的静力分析,引入一种称为分段力学模型的优化模型。首先基于悬链线理论建立悬链线模型进行求解,然后在悬链线模型的基础上对立管进行分段计算,变形大的区域使用大变形梁理论,依据奇异摄动法渐近展开二阶非线性微分控制方程,其余区域使用悬链线理论重新求解,最后合成两部分结果为整体解。与悬链线理论和大变形梁理论对比分析之后发现,分段力学模型对边界条件满足较好,计算结果与高精度的大变形梁理论结果相当。同时,使用分段力学模型来分析了湿重以及刚度的参数敏感性影响。

In order to obtain an analytic method for J lay installation,a static analysis was made of the J lay installation process of a deepwater steel catenary riser,then introduced an optimized model called the piecewise mechanics model. First the catenary model based on the catenary theory was established and solved. Then the riser was computed piece by piece,based on the catenary model,applying large deflection beam theory for the area with large deformation,and developed asymptotically the 2nd-order nonlinear differential control equation on the basis of a singular perturbation equation. This process was repeated using catenary theory for the remaining areas. Last,the results of the two parts were combined into an overall solution. A comparison of the piecewise mechanics model with the catenary riser theory and large-deflection beam theory,shows that the piecewise mechanics model meets the boundary conditions very well,the computation result matches the result of high-precision large-deformation beam theory. The piecewise mechanics model can also be used to analyze the influence of wet weight and stiffness on parameter sensitivity.