Seismic Response Characteristics Of Buried Elbow Pipeline And Pipe-soil Interaction

As an important part of the lifeline system,buried pipelines undertake tasks such as water supply,drainage,heating and transportation of oil and gas resources,playing an extremely important role in maintaining social life safety and normal production.Historical data indicate,the seismic safety of buried pipelines is a prominent problem that needs to be solved in current lifeline engineering.With the development of computer technology and numerical analysis methods,the methods of using numerical simulation and virtual model test technology to study the seismic response law of buried pipelines under complex conditions have become more mature.In this paper,based on numerical models and simulation techniques a systematic study of the seismic response law and constraints of buried elbow pipeline is made to reveal the mechanism of pipe-soil interaction,aimed to provide a theoretical basis for optimizing seismic design of pipelines.The main content of this paper is as follows:Firstly,a large number of examples of earthquake damage and theoretical research results of buried pipelines are collected,the characteristics of the damage of buried pipelines in historical earthquake disasters and the main influencing factors of seismic damage are systematically analyzed.and the latest advances in theoretical research and seismic design methods of buried elbow pipeline are discussed.Secondly,based on ABAQUS software platform,a finite element model for the seismic response analysis of buried elbow pipeline was established,the characteristics and change laws of acceleration,stress,strain,and earth pressure at five different positions of the buried elbow pipeline under earthquake action are analyzed.The research results show that the seismic response is st rong at the elbow and the junction of the pipe section;there are obvious stress and strain concentration phenomena on the inside and both sides of the elbow;the stress on the upper and lower sides of the pipeline is greater than the stress on both sides;The seismic response of the pipe section which is parallel to the direction of seismic wave incidence is greater than that perpendicular to the direction of the seismic wave incidence;there is a large earth pressure difference between the inside and outs ide of the elbow,which can cause pipeline to slide easily and flexural buckling.Thirdly,aiming at the unreasonable design specifications of the current buried pipeline seismic design,referring to the existing theoretical and experimental research results of pipe-soil deformation transfer,a more reasonable theoretical formula for estimating the transfer coefficient of pipe-soil deformation at the maximum strain of the buried elbow pipeline is proposed.Finally,the seismic response law of buried bends under different working conditions is studied,the best embedding method of buried elbow pipeline is discussed,the influence of the pipe wall thickness,pipe diameter,buried depth,pipe-soil friction and elbow angle on the seismic response law is concluded,and the estimation formula for the correlation coefficient of the earth pressure differen ce on both sides of the elbow is proposed.The above research results can be applied to the seismic design practice of the elbow pipeline.