基于滑轮法的水下管汇安装静力学分析

Static Analysis of Subsea Manifold Installation by the Sheave Method

水下滑轮安装法是深水超大型管汇的主要安装方法之一,主要是利用一艘半潜式平台和两艘辅助船只进行水下目标管汇的安装下放。为了研究滑轮法在深水水下丛式管汇中的下放过程,以滑轮安装法中的钢丝绳为分析对象,在不考虑环境载荷的影响下,将水下管汇的安装过程分为3个阶段,建立了3个阶段的静力学平衡方程,分析了钢丝绳的最大拉力以及曲线形状,并研究了水深和管汇质量对其的影响。分析结果表明:滑轮法下放管汇的所有阶段中,钢丝绳受到的拉力均与该点切线与水平轴夹角的余弦成反比;对于给定的水深,钢丝绳任意点拉力的水平分量为常数,该常数随水深的不同而变化;钢丝绳的形状由其单位长度重力和管汇重力决定,进入水中后,其形状曲线都由两段不同的曲线组成。所得结论有助于确保滑轮法安装中钢丝绳的安全使用,并可作为研究各种非线性及动力影响的初始出发点。

The subsea sheave installation method is one of the main installation methods for deepwater super large manifolds, which uses one semi-submersible platform and two auxiliary vessels to install and lower the subsea manifold. To study the lowering process of the sheave method in deepwater cluster manifolds, taking the wire rope in the sheave method as the analysis object, the installation process of the subsea manifold is divided into three stages without considering the influence of environmental load. The static equilibrium equations of the three stages of were established to analyze the maximum tensile force and curve shape of the wire rope, and the influence of water depth and manifold quality on it. The analysis results show that in all stages of the sheave method, the tension of the wire rope is inversely proportional to the cosine of the angle between the tangent and the horizontal axis of the point. For a given water depth, the horizontal component of the wire rope at any point is a constant, which varies with the depth of the water. The shape of the wire rope is determined by its unit length of gravity and manifold gravity. After entering the water, its shape curve is composed of two different curves. The study could help to ensure the safe use of wire ropes in the sheave method and serve as an initial starting point for studying various nonlinear and dynamic effects.