Research On The Mechanical Behavior Of Buried Oil And Gas Pipelines Under Explosive Loads

There are 99%of gas and 70%of oil on the inland transport through the pipeline in the world.Pipeline is the main way of transportation of oil and gas,the structure safety and reliability of it has been widely concerned.Survey found that the third party damage has become a major cause of pipeline failure,and the explosion shock is the most harmful,which will produce lethal damage to pipeline and seriously threaten the operation safety of pipeline.Therefore,it has important theoretical significance and engineering value to study the mechanical behavior of oil and gas pipeline to explosion loading.Currently,the researches about the mechanical behavior of oil and gas pipeline to explosion loading mainly study by the numerical simulation and experiment method,but the content of research is less involved in the buried pipeline,and the local buckling of pipeline.Based on explosion theory and finite element theory,the numerical calculation models of buried pipeline to four kinds of explosion loading were established separately in this paper.Mechanical behavior and sensitivity parameters of buried pipeline were systematically investigated.The specific contents are shown as follows.(1)The numerical results of explosion in air and soil are compared with the related theory,empirical relations and experimental results,and it shows that the numerical method in this paper can better simulate the process of explosion.When the object of study is located in the larger scaled distance,the simulation results are more accurate.(2)Numerical models of buried pipelines to the surface explosion loading were established,mechanical behavior and buckling phenomenon of the non-pressure and pressure pipeline were investigated.The effects of explosive quantity,diameter-thickness ratio,buried depth and internal pressure on the buckling behavior were studied.The maximum strain and cilver carp of pipeline were gained by multivariate fitting method.(3)The numerical models were established to investigate the response of buried pipelines to the explosion loading in air and soil.The effects of the pipeline parameters,explosion parameters and soil properties on the response of pipelines were discussed.The semi-empirical formulas of the maximum strain and cilver carp of pipeline were presented.For the explosion loading in air,the pipeline is more dangerous in rock layer than it in soil layer.The explosion wave has less effect on the pipeline when the explosive depth is small.Therefore,the explosion loading in soil is more dangerous than it in air for the buried pipeline.(4)For the explosion in surface and soil,the numerical models of buried pipelines to explosion loading in two points were established.The effects of the interval time,pipeline parameters and explosion parameters on the mechanical behavior of pipelines were discussed.For the explosion loading in two points,the pipeline is more dangerous due to the fact that the deformation and plastic strain of pipeline is larger than the explosives explode simultaneously.