Study On Stress Analysis And Settlement Treatment Of Natural Gas Pipeline On Soft Ground Under Uneven Settlement

Natural gas pipeline transportation is one of the main ways of natural gas transportation,and many natural gas pipelines in coastal areas are laid on soft ground,but due to the large amount of deformation after soft soil is loaded,it is easy to cause the pipeline laid on it to be uneven The settlement effect was destroyed.Natural gas is a flammable and high-explosive hazardous chemical with a high risk factor.Once the uneven settlement caused by the soft ground causes the pipeline to rupture or leak,it may cause fire and explosion accidents.Therefore,in order to ensure the safety of the operation process of the natural gas pipeline,it is of practical application to carry out stress analysis and research on the settlement treatment of the uneven settlement of the natural gas pipeline laid on the soft foundation.main tasks as follows:(1)According to the on-site environment and geological situation of natural gas pipeline laying,formulate a stress monitoring program,and use static strain gauges to carry out stress monitoring for 9 months of natural gas pipelines for up to 12 months.The stress monitoring data shows that the maximum value of the axial additional stress in the monitoring point is 145.09MPa and the maximum value of the circumferential additional stress is 241.71MPa.From the environmental humidity and temperature,wire resistance,strain gauge quality and patch etc.,the error analysis of the stress monitoring test results and provides a means to reduce errors,the monitoring results are credible.(2)Starting from the type of load that may be received during the operation of the natural gas pipeline,analyze the laying of the buried pipeline and the calculation method of the earth pressure.On the basis of introducing the simplified model of elastic foundation beam,the soil spring model and the non-linear contact model of the pipe-soil interaction,the calculation model of the buried pipeline main pipeline and the substation pipeline is established.The soil spring model is used to model and analyze the buried pipeline trunk pipeline,and the deformation equation of the pipeline across the non-settlement zone and settlement zone is derived as Mb=ηEI3y0/W The elastic foundation beam model is used to model and analyze the pipelines of the substation,and the axial stress calculation expressions of the open-air pipeline and the buried pipeline under uneven settlement of the foundation are derived.(3)Use finite element software to perform finite element simulation analysis on the established three-dimensional pipeline model.The simulation results show that under normal working conditions(7 MPa),the maximum equivalent stress of the pipeline under settlement conditions occurs at the tee side of the buried pipeline(239 MPa)and the tee on the ground(228 MPa).Due to the settlement of the foundation,the horizontally buried pipeline will be stressed by squeezing or stretching.Compared with the horizontal straight pipe,the stress at the tee and elbow is significantly higher than that at the straight pipe(4)Under the condition of satisfying the boosting conditions of the natural gas distribution station,combined with the finite element simulation analysis of the stress change value of the pipeline from 7MPa to 9MPa,the natural gas distribution station pipeline adopts the settlement treatment of extracting the steel plate to reduce the elevation release stress method.This treatment method combined with on-site stress monitoring to ensure that the natural gas pipeline still meets the safety requirements after the pressure increaseThe research results of this paper can provide theoretical support and practical basis for the settlement control of natural gas pipelines under soft settlement.