Research On The Bearing Capacity Of Submarine Pipelines With Dent Defects

Mechanical damage is one of the main causes of failure of submarine pipelines,and dent is a common mechanical damage.The dent will reduce the overall or local mechanical properties of pipelines.Hence,the evaluation of dented submarine pipelines is very important.In this paper,the static residual strength of dented submarine pipelines is studied by means of experiment test and finite element method.The main work consists of the following parts:1)The experimental study of submarine pipeline under static load is carried out.Three groups of full-size specimens were designed and tested under axial,bending and bending loads respectively.Each group consists of a intact pipeline and a dented pipeline to study the effect of the dent defect on the bearing capacity of submarine pipelines.The failure modes,displacement-load curves and strain curves of the specimens were recorded in the tests.The results show that the dent defect has a certain influence on the mechanical properties of submarine pipelines.2)Based on the test,the finite element model of submarine pipeline is built ed by using ABAQUS.The accuracy and reliability of the model is verified by experimental data.The results show that the finite element model can accurately simulate the formation of indentation and the mechanical properties of submarine pipeline specimens under static load.It provides the conditions for the parameter analysis in the following chapters.3)Parametric analysis of residual strength of dented submarine pipeline is carried out.The effects of dent depth,width and shape on the residual strength of dented submarine pipelines were studied.According to the influence law,the mathematical model of empirical formula predicting the residual strength of pipeline is established by these parameters.Finally,a large number of models with different parameters are established by ABAQUS.Based on the regression analysis of finite element data,a formula for calculating the residual strength of dented submarine pipelines is proposed.