The Safety Reliability Study Of Buried Pipeline Crossing Fault Under Seismic Load

As China is a frequent geological disaster-prone country,pipeline which is an important part of the lifeline inevitably passes through typical geological disaster areas,such as strong earthquake areas and active fault zones.These natural disasters can cause pipeline prone to excessive deformation and failure,resulting in significant economic losses and casualties.Therefore,the study of buried pipelines crossing fault under seismic loading is of great significance to the safety and reliability to ensure the normal operation of the pipeline.Based on strain design method,this paper studies the impact of seismic waves as well as active faults on buried pipelines and discusses the factors affecting the safe operation of the pipeline.The main aspects of the following work can be concluded as follows.First of all,the paper summarizes the strain design criteria in home and abroad,and analyzes failure modes of buried pipeline under typical adverse geological conditions,as well as its safety assessment criteria under different failure modes.Secondly,the strain calculation methods that are now widely used in buried pipelines under the effect of seismic waves are introduced.What's more,the influence of site conditions,pipeline geometry parameters,internal pressure and temperature on the pipeline axial strain is studied.Using the finite element software,the example calculation and strain check of pipeline crossing the active fault of Yidian-Qianxian-Meiyuan has been presented and the impact of the diameter,wall thickness,buried depth,fault offsets,internal friction angle of the soil and other factors on stress and deformation of pipeline crossing the fault is studied.Among them,buried depth,fault offsets and internal friction angle of the soil are positively correlated to the maximum axial strain of pipeline;diameter and wall thickness are positively correlated to the maximum axial strain of pipeline.Then,by inputting seismic waves,the change rules of maximum displacement and maximum shape variables of buried pipeline under different seismic intensity,site conditions,pipe geometry parameters are analyzed by using time history analysis method.Moreover,the paper has also studied the influence of random variables on the safety reliability of buried pipeline crossing fault under the seismic load.The results have shown that the design and construction should try to avoid seismogenic faults,and a large-diameter,thick-walled steel pipe which is shallow buried in relatively dense soil is supposed to choose.In addition,it is propitious to reduce project costs under the premise of meeting the reliability requirements,and provide the basis for security design of the long-distance pipeline crossing seismogenic faults.