Seismic Security Study Of Oil Pipeline Containing Crack Defects On Differential Settlement Site

With the rapid development of society, the oil and gas have become the importantstrategic resources of economic development. The main means of transportation of oil andnatural gas are the pipeline transportation. Pipeline has become an important part of the urbandevelopment, modern industrial production and people’s life. During the process oflong-distance pipeline operation, many issues also started to appear, such as the phenomenonof uneven settlement around the pipe, the pipe crack defects and earthquake disaster, whichhave become the main cause of pipeline accidents, so the seismic security study of oil pipelinecontaining crack defects on differential site becomes very important.In the first chapter, the research background of the uneven settlement sites, crack defects,and the pipeline seismic performance were described, and the main research methods of thesisand the theoretical analysis model were proposed.In the second chapter, the model of the pipe used in theoretical seismic analysis methodand the time-history method were introduced, by the use of ANSYS Software, SOLID95unit,SOLID45unit and COMBIN39unit are used to simulate the part of pipeline Containingcracks, pipeline and springs of the uneven settlement of soil around the pipe. Thedisplacement, acceleration and the peak and waveform of stress time history in crack tippoints of pipeline were extracted and compared, changes of the seismic performance of theuneven settlement were also discussed.In the third chapter, the time-history curves and their stress-strain values ofrepresentative node at various pipeline model were analyzed and the influence of differentparameters on the seismic performance of pipeline were researched by changing theparameters-the scope of settlement site, the distance between Cracks center and the junctionof uneven settlement and the subsidence area, and the depth and length of the crack.In the fourth chapter, assessment method of R6criteria and API579criteria were brieflyintroduced, and respectively the two methods were used to evaluate the safety of the seismicperformance between several kinds of cracked pipeline models on the uneven settlement site,ultimately theoretical basis for the Maintenance and replace of Cracked pipeline on theuneven settlement site were provided.