Mechanical Behavior Analysis Of Long Distance Buried Pipeline Failure In Loess Plateau

The west-east gas Transmission project is the pipeline project with the longest distance and the largest diameter in China.The safety of the pipeline is seriously threatened by the complexity of the terrain and the multiple geological disasters it passes through,especially in the loess Plateau.As the largest and most typical loess region in the world,its structural particularity and collapsibility of loess make various geological disasters occur frequently and further aggravate the risk of pipeline damage.Therefore,considering the multiple loess plateau region of geological disasters,and the region of various kinds of geological disasters caused the severity of the consequences of the pipeline accidents,to explore the loess plateau region as soon as possible for long-distance buried pipeline deformation failure mechanism,forecast pipeline risk of damage to the pipeline design,pipeline safety evaluation and protection countermeasures such as to provide scientific basis.According to the characteristics of the main geological disasters in the Loess plateau,the failure forms and deformation characteristics of pipelines are summarized and analyzed in this paper.Based on the above analysis,a pipe-soil interaction finite element model was established for the failure of buried long-distance pipeline in loess Plateau,and the influence of pipeline parameters and several key parameters in external conditions on pipeline failure was analyzed.The failure mechanism was studied according to the calculation results,and the reliability of the calculation results of the finite element model was compared with the verification test results.Considering loess collapsibility,the rainfall seepage zone of collapsible loess is set as porous medium domain in the finite element model of pipe-soil interaction,and the failure mechanism of pipeline is analyzed through fluid-structure coupling calculation of porous medium.In order to evaluate the failure risk of pipeline in the future time,considering the time cumulative effect of failure risk in the process of pipeline operation,the grey neural network model was organically combined with artificial neural network to construct the failure probability prediction model of buried long distance pipeline,and then the failure warning model of buried long distance pipeline was developed.Combined with the actual data,the failure probability calculation and risk grade classification are carried out,which provides a reference for the safety management of buried long-distance pipeline and the formulation of disaster prevention and emergency plan.