Finite Element Simulation Study On Third-party Excavation And Construction Damage Of Gas Pipeline

Pipeline is the core infrastructure of natural gas transportation,and natural gas has the inherent properties of inflammable and explosive.Once the gas pipeline is damaged,it will not only cause material loss of pipeline equipment,but also may cause serious fire and explosion accidents if the natural gas leakage is caused.To ensure the pipeline is not damaged by the third party and to maintain the safety of the pipeline itself has become a key link to ensure the smooth transportation of natural gas.In China,pipeline damage caused by excavation around buried pipelines has become a major risk factor for pipeline transportation safety.In this paper,ANSYS Mechanical(APDL)and ANSYS AUTODYN are used to build three-dimensional model of buried gas pipeline damaged by excavator ballast and excavation load,simulate the damage process and analyze its dynamic response.The research contents and achievements are as follows:(1)According to the force condition of buried gas pipeline,the external load is divided into rolling load and excavation load,and analyzes the mechanical characteristics and failure conditions of pipeline,which is the research foundation of finite element simulation of pipeline stress damage.(2)The finite element model of gas pipeline under rolling load and excavation load is established and simulated.The results show that the damage caused by rolling load is small,while that caused by digging load is large.At the same time,in view of the complex working conditions of excavation,the pipeline damage under different excavation angles,directions and other factors is analyzed comprehensively.(3)Based on the relevant specifications,the dynamic parameters of mining load,pipe wall thickness,pipe contact bucket tooth number,gas pressure and overburden thickness are selected to conduct the pipeline damage simulation.The results show that the excavation load has the greatest influence and the gas transmission pressure has the least influence on pipeline damage.(4)Through the analysis of the damage simulation results of gas transmission pipeline under different dynamic parameters,the evaluation indexes are selected based on relevant specifications,and the vulnerability evaluation model of buried pipeline under excavation construction environment is constructed by using analytic hierarchy process,and the calculation formula of vulnerability evaluation value is deduced,which is verified by the actual example,so that it can be applied in pipeline risk evaluation.(5)Through the analysis of the damage consequence of gas pipeline,based on the finite element simulation technology and the vulnerability assessment model,the critical safety wall thickness of gas pipeline under the excavation construction environment is determined,and as a result the robustness of the pipeline will be improved.The finite element simulation model and vulnerability assessment model established in this paper are used to carry out operational analysis in combination with the actual conditions of mining operations.Therefore,the research results of this paper put forward the solution ideas and technical solutions for improving the essential safety of gas transmission pipeline,which has certain practical significance.