Most pipelines are constructed by the laybarge method, and most pipelay barges carry out pipelaying in the S-lay mode, in which the articulated stinger is often used. See Palmer (1994). In order to maintain the stresses under a certain allowable level, a static bidimensional analysis is used to choose the parameters influencing laying operations because the stress due to static deformation is the main one in the laying process, as described by Gnone et al. (1975). However, the finite element method used for this analysis requires a great deal of computer time due to the large deformation, so that optimization on the laying parameters can only be performed with difficulty. In the papers of Huang and Zhu (1986) and Konuk (1980) a perturbation technique was proposed, however it is only suitable for a pipeline laid with a rigid stinger, in which case the deformation of the stinger segment is known and therefore only the suspended segment needs to be treated. This paper presents a method of calculating the large deflection of submerged pipelines laid with an articulated stinger in which the buoyancy in every element is adjustable. The stinger segment and the suspended segment of the pipeline are treated separately with a singular perturbation technique and by the use of some additional relation and the continuity condition at the joint between the two segments, an approximate solution of the second order to the deflection of the whole pipeline is obtained. Because the computer time for the method is greatly reduced in comparison with that for the finite element method, the operation parameters in laying can be optimised over a large region using a mathematical programming method. The efficiency of the proposed method is demonstrated by an example.
Optimization of buoyancy of an articulated stinger on submerged pipelines laid with a barge
Auftriebsoptimierung eines auf eingetauchten von einem Schiff verlegten Pipelines angeordneten gelenkbehafteten Steigrohres
Ocean Engineering ; 24 , 4 ; 301-311
1997
11 Seiten, 4 Bilder, 5 Quellen
Article (Journal)
English