Study On Seismic Behavior Of Buried Oil Pipeline Containing Crack Defects

With the exploitation of oil and natural gas,the application of buried pipelines is becoming more and more widespread.Crack defects are also becoming more and more prominent in the process of transporting oil and natural gas pipeline.At the same time,China is a country with frequent earthquakes,the earthquake will have a great impact on the buried pipeline with cracks,which can lead to abnormal operation of the pipeline.In order to understand the influence of earthquake on buried pipelines more explicit.The buried pipeline with crack,which diameter is 1016 mm and wall thickness is 21 mm,is studied.The finite element analysis model is established by using the software ANSYS,and the seismic performance is researched.Under VIII and IX seismic intensity,the stress and strain of pipelines with different crack sizes are discussed respectively in the I,II and III soil type.It is found that the influence on the pipeline is very different in the situation of different seismic intensity,different site type and different crack size by simulating.Firstly,the higher of the seismic intensity,the greater risk of buried pipeline with cracks.Secondly,the damage of buried pipeline is the lowest in the II site,and the III site is more serious,and the I site is the most serious under the same seismic intensity.Thirdly,the deeper depth and the shorter length of the cracks on the pipeline are more likely to generate the crack tip stress concentration phenomenon,which makes the pipeline more vulnerable.Finally,the API 579 criterion is introduced briefly.Under the seismic action of earthquake wave,the safety of buried pipeline with crack is evaluated by using the criterion.It provides a theoretical guidance for the problem of replacement,maintenance or normal service of buried pipelines with cracks.