Study On Multiphase Coupling Dynamic Response Of Buried Oil And Gas Pipeline Explosion Based On Different Failure Modes

The buried pipelines have broad application prospects in oil and gas transportation,and are one of the main methods of long-distance oil and gas transportation.However,due to accidental external explosion loads such as leakage and explosion of nearby oil and gas pipelines,engineering blasting construction,and terrorist attacks,the oil and gas pipelines will be destroyed under the transient impact load,resulting in oil and gas leakage causing casualties and major property losses.This paper calculates the external explosion load of the buried pipeline,analyzes the response of the buried pipeline under the external explosion load and verifies it with the experiment,establishes the evaluation conditions of the pipeline strength,stiffness and fatigue failure.Under the action of failure analysis,combined with the analysis results of influencing factors of buried pipeline external explosion,it puts forward a solution of buried pipeline external explosion failure protection and buried pipeline external explosion safety protection measures.The specific research work carried out is as follows:Considering the physical quantity transfer process between the fluid in the soil,pipeline and pipe,a multiphase coupling numerical model for the fluid in the explosive,soil,pipeline and pipe is established.According to the GB 50253-2014 oil pipeline design specifications,establish the failure criterion of the pipeline strength and stiffness under the action of the external pipeline explosion stress wave.A finite element model for calculation of external explosion stress waves of oil and gas pipelines is established,and strength and stiffness failure analysis of pipeline response of buried oil and gas pipelines under the effect of external explosion stress waves are carried out.According to the national standard JB4732-1995(R2005)"Steel Pressure Vessels-Analysis and Design Standards" and the interpolation formula,the fatigue life of X70 pipeline steel is obtained by interpolation,and the fatigue failure criterion of the pipeline is established.The dynamic response of external explosion of buried oil and gas pipelines under the action of explosion seismic waves is analyzed,and the stress time,frequency and radial deformation curves of oil and gas pipelines are obtained.The fatigue failure analysis of buried oil and gas pipelines under the action was carried out.The influencing factors of different explosive locations,different burst distances,different soil properties,different pipe diameters,different pipe wall thicknesses,different fluid velocities,different fluid delivery pressures,and different fluid properties of explosives in buried pipelines were analyzed.The stress and radial deformation of the pipeline under theinitiating condition in soil are larger than the stress and radial deformation in the initiating condition in air;as the burst distance increases,the peak stress and radial deformation peak of the buried pipeline become greater The smaller,the stress and radial deformation of the pipeline when the soil property is clay are less than the stress and radial deformation of the pipeline when the soil property is clay;the fluid velocity in the tube increases,and the pipeline stress and radial deformation increase;The pressure of the fluid in the pipe increases,and the stress and radial deformation of the pipe decrease;the stress value of the pipe under the air condition is greater than the stress value of the pipe under the water condition;the pipe wall thickness increases,and the pipe stress Decrease;the diameter of the pipeline increases and the stress of the pipeline decreases.According to the analysis results of influencing factors of external explosion,a solution to the failure protection of buried pipeline external explosion and safety protection measures for buried pipeline external explosion are proposed.