Study On Failure And Risk Assessment Of Defective Submarine Pipelines

Through numerical simulation and experimental verification,the influence of pipeline defects such as ellipticity,corrosion thinning and sunken on the safety of pipeline structure is studied,and on this basis,risk assessment of defective submarine pipelines is carried out.Study on the reasons of submarine pipeline ovality produced;in the deep sea pressure cabin pipeline crushing experiment,by adjusting the submarine pipeline specimen local ellipticity,study the ellipticity influence on the submarine pipeline critical crushing pressure,and critical crushing to obtain specific ellipticity of submarine pipeline under pressure;through the comparison of the experimental data to verify the feasibility the simulation of ellipticity of pipeline in ABAQUS compression process,and through the ABAQUS simulation of submarine pipeline with ellipticity length on the compressive properties.By means of numerical simulation of submarine pipeline defects under cut thin internal pressure damage,the length,the width and the depth of the rule of thin defects for sensitivity analysis;modeling process of submarine pipeline sag depression model,depression model acquisition pipeline crushing data;critical damage fitting using neural network way thinning defects the submarine pipeline internal pressure,using neural network variable reduction factors the effect of weak dimension recognition of sag submarine pipeline critical crushing pressure.By theoretical deduction and numerical simulation,the influence of damping ratio on the critical crushing pressure of elliptical pipeline under sine and cosine loading is studied,and the reasonable damping value of submarine pipeline is determined by DNV code and numerical simulation.The influence of sine and cosine load on critical pressure of elliptical pipeline under damping condition is studied,and the sensitivity of external pressure and circular frequency of dynamic load is analyzed.The difference of structural response of elliptical pipeline under long axis loading of positive cosine load and short axis direction loading is studied.A fault tree of defective submarine pipeline structure is established.A new expert scoring method for data processing is proposed,and the probability of failure of submarine pipeline structure failure is calculated based on them.Combined with the risk evaluation matrix of submarine pipeline,the risk assessment of the defective submarine pipeline is carried out,and the corresponding measures of risk control are put forward.