Failure Analysis Of Pipeline Under Impact Load Of Falling Objects

With the development of offshore oil and gas resources more and more frequently,the safe operation and protection of submarine pipelines have been widely concerned.Due to the influence of the third party activities,the submarine pipeline may have buckling failure under the impact of falling objects.Therefore,it is necessary to analyze the dynamic response of the submarine pipeline under the impact of falling objects,and study the factors affecting the buckling failure and failure,so as to seek reasonable protective measures and ensure the safe operation of the pipeline.In view of the above reasons,this paper focuses on the buckling failure of single-layer pipe and single-layer pipe with concrete counterweight layer under the impact load of falling objects.With the help of theoretical analysis and numerical simulation,the failure mechanism of the pipeline after impact is explored.According to the situation of single-layer pipe impacted by falling objects,the research methods of submarine pipeline impacted by falling objects are summarized,and the applicability and limitations of empirical formula method,energy method and numerical calculation method are analyzed.The simulation model is established to calculate the pit depth and additional ellipticity caused by impact,and the results are compared with the full-scale pipeline impact test results to verify the accuracy of the simulation model Based on the above model,the influence of the pipe diameter thickness ratio,support conditions and operating pressure on the submarine pipeline under the impact load is further studied,and the energy change and the maximum Mises stress of the pipeline during the collision process are analyzed.Aiming at the single-layer pipe with concrete counterweight layer under the impact load of falling objects,the relationship between the depth of pit and the energy absorption between the concrete counterweight layer and the single-layer pipe is calculated,and the protection effect of the concrete weight layer on the pipe is analyzed.On this basis,the impact energy,falling object shape,pipeline buried depth and operation are analyzed The sensitivity factors such as pressure,soil parameters,pipe diameter thickness ratio and concrete weight layer thickness were analyzed by parametric analysis,and the variation trend of pipe pit depth and energy absorption of counterweight layer with the above parameters was analyzed.According to the impact load of the suspended span submarine pipeline,the causes of the pipeline are analyzed.According to the properties and deformation of the seabed soil,the constitutive model is selected reasonably to calculate the impact force and pit depth of the pipeline after the impact;the influence of the impact energy,the length of the suspended span section and the impact position on the pit depth is determined.