Research On Failure Mechanism And Evaluation Method Of Offshore Submarine Pipeline Induced By Seabed Earthquake

In this dissertation,the finite element analysis model of offshore submarine pipeline is established by finite element analysis software,the failure mechanism of offshore submarine pipeline induced by seabed earthquake is studied,the failure law is analyzed,and the weak position of offshore pipeline under earthquake is explored.Explore the influence degree of the factors affecting the failure of the nearshore pipeline,and judge the sensitivity of each factor;Based on machine learning classification method,an evaluation method of offshore submarine pipeline damage induced by seabed earthquakes is established.The main work contents are as follows:(1)The influence of different seismic wave input modes on the damage of offshore submarine pipeline is explored,and the most suitable seismic wave input mode is determined for the finite element simulation analysis of offshore pipeline under earthquake.By applying normative synthetic seismic wave and natural seismic wave respectively to offshore submarine pipeline model,the weak position of offshore submarine pipeline is determined from three angles of equivalent stress,axial strain and deformation,which also provides ideas for seismic analysis of similar offshore pipelines.(2)The influence of pipeline diameter,wall thickness,buried depth,dip Angle of seabed surface and elastic modulus of seabed soil on the failure of offshore submarine pipeline under earthquake is analyzed.The sensitivity sequence of these five factors was analyzed by orthogonal test and decision tree regression model,which provides theoretical reference for the design of offshore pipeline.(3)Based on the existing criterion of pipeline failure and the simulation results of offshore pipeline failure under earthquake,a new method for offshore submarine pipeline failure under earthquake is proposed.Combined with decision tree classification model,naive Bayes classification model and BP artificial neural network classification model,the evaluation method of offshore submarine pipeline damage induced by seabed earthquake is explored,providing a new idea for the evaluation method of pipeline damage.