The Key Techonolies Reaserch Of Marine Pipeline Sea Butt

Marine pipeline butt technology is an important technology in the process of layingpipeline and pipeline maintenance. From the1950s, foreign began to study marine pipelineand arrived to peak by the1970s. A series of model and algorithm were put forward in thisperiod and it was successfully applied in the engineering practice. The domestic researchstarted from the1980s and mainly concentrated in the pipe in the vertical plane in twodimensional analysis and dynamic research. marine pipeline butt study still exists thatinteraction mechanism between seabed and pipeline is unknown, pipeline joint buckling modeand buckling joint influence factors is not clear, pipeline deformation and stress change ruleresearch is still blank, influence from pipeline lifting and laying scheme is for pipe buttconstruction and so on. In allusion to the pipeline sea butt the problems in the research, thispaper made four sorts of research work.1、This paper studies the marine pipeline and seabed interaction mechanism andimproves settlement calculation method of laying pipeline under the condition of the viscosityfoundation soil and sand sex foundation soil. So that it is used more widely. The lateral earthresistance calculation method of the sand seabed and clay on the seabed was put forward. Byusing nonlinear seabed soil calculation model research buried pipeline axial large deformation,it more accords with the practice of engineering and can effectively improve the accuracy ofcalculation. This paper established the pipe soil elastic sliding friction model and introducedpipeline soil friction effect of anisotropy. This model can not only improve the convergenceefficiency and more accord with pipe soil actual friction characteristics, but also can more realsimulation of the interaction between pipeline and seabed.2、This paper studies the marine pipe butt joint force buckling. This paper established thenumerical model of pipe joint and probed into the pipe joint buckling analysis method andbuckling mode. From the research, it is known that pipeline the buckling critical load andbuckling deformation and pipeline design, welding joint, joint construction methods andpipeline in service, operation of the pipeline whole life period is closely related to the process.Pipeline the critical buckling load and buckling deformation changed with these parameters.Pipeline cycle loading action will cause pipe plastic deformation and stress superpositiongrowth, thus obviously reduces the pipe joint the buckling critical load. 3、This paper established the pipe butt process of numerical model, and verified it. Inestablishing the basis of numerical model, the five kinds of pipe laying scheme studieddifferent sink put method for pipeline final form and the influence of stress. Research showsthat the pipeline settling put after completing the final form and bending moment distributionis very sensitive and laying scheme tiny difference will lead to very different laying the results.The stress of laying marine pipeline changes complex and lifting point release not harmoniousextremely easy to lead to the pipeline local appear stress peak. In order to get good heavy puteffect, in the pipeline lower initial should with engineering ship lateral is given priority to andin the lateral later should be a little slow lifting rope two lower speed. So that we can avoidthe maximum bending moment occurred in butt outlet. That engineering ship lateral distanceis too small will increase the pipe butt joint interface and the bending deformation curvatureand resulted in the corresponding moment increase. Even lower strategy will lead to theincrease of the bending moment in horizontal pipeline. And it reveals the steady flow, pipesoil coefficient of friction in pipe form and the influence of stress. Research shows that thelongitudinal unsteady flow in pipe butt process of space form and stress distribution influenceis lesser and lateral flow will cause the change of pipeline deflection and stress level of high.The damage effect is obvious. Rough seabed to the pipeline lateral have side effect and pipesoil friction coefficients on the pipeline settling put finished pipe bending moment distributionunder the influence is bigger. The seabed is more rougher, the greater the final bendingmoment pipeline. Through the pipeline sea butt numerical model research, this paper revealsthe pipe butt in the process of maximum stress change rule. Research shows that in the liftlifting stage pipe stress increased rapidly to a higher stress level. In the pipe end leveling buttstage pipeline maximum stress changes smaller and the approximate linear rise. The overallstress level keep in pipeline lift hanging later higher stress state and heavy put stage pipelinemaximum stress there is a big fluctuation. And the peak stress may occur, but pipe wholemaximum stress state of decline.4、Based on general finite element software modeling complex, calculating duration islong and not easy to convergence. Relying on the victory oil field exploration project designand research institute "marine pipeline butt technology numerical simulation and softwaredevelopment", our laboratory independently researched and developed a set of modeling isconvenient, calculation of quick and convenient application of submarine pipeline buttsimulation software. It can convenient calculation pipe deformation and stress, determine thehanging point position and height, optimization design and construction scheme.