Research On Seismic Response Of Subsea Pipeline Based On Artificial Boundary

In the process of deepwater drilling,the submarine pipeline is an essential part of oilfield development,operation and maintenance.Submarine pipeline damage records tells us that the influence of earthquake on the submarine pipeline can not be ignored.Submarine pipeline should as far as possible to avoid geological disaster,if necessary,disasters influence of disasters on pipeline should be given detailed research.The characteristics of earthquake disasters are short,high frequency and strength.Submarine pipeline under earthquake would go through fracture,buckling damage.Offshore pipeline is different from onshore pipelines,If damage not only produce economic losses,but also the destruction of the extreme ecological environment.At present,the domestic engineering designers even don't have one code about the seismic design of subsea pipeline.CCS and DNV didn't give a concrete pipeline seismic design method.Main difficulties of seismic dynamic are: dynamic soil constitutive model,SSI dynamic contact model,the artificial boundary,manual processing of seismic wave as well as convergence and stability of FEA.Contact model is used to simulate the tube-soil interaction,making up for the shortcomings of traditional method with a spring instead of soil.Artificial boundary is set in soil boundary to solve radiation damping problem of elastic wave in the boundary,so that it can simulate actual dynamic response of soil.Soil constitutive use the Mohr-Coulomb model and the equivalent linear model,Mohr-Coulomb soil model can study the plastic strain;equivalent linear model can simulate the hysteretic properties of soil under the cyclic loading and nonlinear property.Through the finite element calculation,we obtain the pipe intuitive motion state in the process of earthquake,the change of stress and strain;this paper study the influence of buried depth,diameter,and seismic wave input method on stress,strain and displacement of pipeline.In this paper,the research results have important reference value for mechanism of earthquake damage of submarine pipeline,and the establishment of codes.