Study On Failure Evaluation Method Of Suspended Settlement Of Long-distance Pipeline With Pitting Corrosion

Buried long-distance pipelines are one of the main carriers for transporting oil and natural gas.Long term underground laying can easily cause random pitting damage due to the influence of corrosive media in the soil.At the same time,due to long-distance transportation,various types of landforms and geological conditions will pass along the way,and natural disasters can also lead to large-span suspended failure,posing safety hazards to pipeline operation.Therefore,it is crucial to study the structural performance of long-distance pipelines with pitting corrosion damage under the collapse settlement of pipeline foundation soil,and provide failure assessment and safety risk prediction before accidents may occur.This article adopts a combination of theoretical analysis and numerical simulation to study the evaluation method for suspended settlement failure of buried long-distance pipelines.The main research content and results are as follows:Firstly,study the construction method and mechanical performance analysis of a suspended settlement model for buried long-distance pipelines.Taking into account the coupling relationship and load characteristics of buried pipeline soil interaction,a nonlinear contact model of pipeline soil based on Winkler theory is proposed.Taking a certain engineering pipeline as the research object,a three-dimensional numerical model of pipeline suspended settlement based on pipe soil interaction was established using finite element method.The effects of internal pressure and suspended length on the mechanical properties of the pipeline were obtained.Secondly,simulation of suspended settlement and mechanical performance analysis of buried long-distance pipelines under pitting corrosion damage were conducted.Analyzing the corrosion characteristics of buried pipelines,with pitting damage as the research object,a regular cylindrical pitting pit model was used,Matlab programming and Ansys were combined to propose a method for constructing a random pitting corrosion model for pipelines.A numerical analysis model for suspended settlement pipelines containing multiple random pitting corrosions was established,and the suspended settlement of pipelines was simulated under different pitting parameters and pipeline factors.The depth,quantity,radius,and internal pressure of pitting corrosion were obtained The influence of parameters such as the length of the pitting zone on the mechanical properties of buried suspended pipelines shows that the depth,quantity,radius,and internal pressure of the pipeline are the main factors affecting the stress magnitude of the buried suspended settlement pipeline.When pitting damage occurs in the suspended settlement pipeline,the internal pressure of the pipeline should be given special attention.Finally,study the evaluation method for suspended settlement failure of buried long-distance pipelines with pitting corrosion damage.Through the above theoretical analysis and numerical simulation,analyze the mechanism of pipeline settlement failure and determine the failure criteria of the pipeline.By analyzing the failure probability of buried long-distance pipelines with pitting corrosion and suspended settlement,a risk assessment matrix is established to determine the risk level,ultimately determining the risk level and developing corresponding risk prevention measures.Finally,the multiple regression method is used to calculate and analyze the influencing factors of pipeline stress variation coefficient in engineering examples,achieving failure consequence assessment and providing decision-making basis for pipeline maintenance,repair and management.