Calculation And Study On Force Of Pipeline In The Deepwater S-Lay Operation

At present, many of the subsea pipelines are installed by pipe-laying vessel method. Inorder to avoid the cross-section hanging yield or fracture occurs, ensure the safety ofoperations and improve operating efficiency, carrying out pipe deformation and stressanalysis is very necessary. The paper studies S-lay operation mainly in the following aspectsof work.First of all, in this thesis, the load case of S-lay method is researched and analyzed, andbased on this, the pipe model is subdivided into the upper lower segment, middle segmentand lower curved segment; And then beam bending theory and stiffened catenary theory areused as the base theories for calculating internal force distribution of middle segment andlower curved segment separately, by assuming the upper curved segment to be an idealcircular arc; Based on this, through a numerical simulation of static analysis by Matlab,developed analysis procedures. And the calculation results of development procedures andpredecessors using OFFPIPE professional software were compared and analysed, confirmingthe availability of the preparation software. After the case contrast study, some sensitivityanalyses have been preformed with respect to the key parameters for deepwater s-lay methodto obtain the loading characteristics and variation principles.In this thesis, based on the static analysis, the force on subsea pipeline caused by waveand current is calculated using Morison formula, and then the influence of the laying patternsand internal force distribution is also analyzed. Simultaneously; based on this, included in theship motion influence on pipe laying operations, the movement of pipe-laying vessel issimplified as one-dimensional heave motion, and the time-domain analysis about dynamicresponse of subsea pipeline is done using Newmark-β method, finally, comparing the resultwith static analysis.