Sediment Threshold And Local Scour Around Submarine Pipelines Under Wave Action

As a carrier to deliver oil and gas from offshore platform to land, submarine pipeline has many merits, such as continuously deliver, large conveying capacity convenience management and so on, and it has been used extensively in ocean engineering However, submarine pipeline often under severe conditions, sediments will be carried away by local flow caused by wave and tide, this may cause the pipeline to be suspended and lose its stability, finally, lead to break or other accident, bring about tremendous economic loss and environment pollutionThis paper based on a model experiment done in a large wave flume, discussed the scour stability of submarine pipelines under wave actionFirst of all, a brief review of wave theory is made and the water particle velocities of Airy wave and Stokes second-order wave are analyzed The scope of application of these wave theories was given, to illustrate why the paper makes use of Stokes second-order theorySecondly, discuss sediment threshold under wave action-the keyproblem in seabed erosion Sediment threshold under wave action is a front edge subject of sediment research, up to the present, most of initiation criterions were obtained from experiments results, and may not have general applicability According to the boundary layer theory proposed by C.C.Mei &M.A.Foda(1981), this paper analyzes the effect of wave-induced seepage force on the sediment threshold, and expects to perfect the initiation criterion theoreticallyThirdly, carry out a model experiment in a large wave flume, finish several groups of experiments to study local scour around submarine pipelines Observed and described the development of scour, measured equilibrium scour depth , and estabilish the relationship between non-dimensional scour depth and KC number by nonlinear regression analysiSoThen, the VOF for surface tracking and standard k-s turbulence model are applied to numerical simulation of wall shear force on flat bottom 0 The result shows that, the presence of submarine pipeline will strongly change the flow pattern in its neighbourhood, cause the wall shear to quickly rise.,Finally, the paper introduces several scour protection technologies now widely used both here and abroad 0...