Stress And Strain Analysis,monitoring And Early Warning Of Buried Pipeline Under Landslide Action

China has a vast territory and complex geological environment.In the process of long-distance pipeline laying,it is inevitable to cross the area with frequent geological disasters.Landslides and other geological disasters along the way have an unsafe impact on the transportation of oil and gas resources in China.The large displacement deformation of buried pipeline under the push-pull action of landslide leads to plastic deformation failure of pipeline,resulting in leakage,explosion and other accidents.Therefore,taking the typical geological disasters of landslide as the research background,this paper analyzes the strain distribution characteristics along the buried pipeline under the action of landslide and the influence law of various parameters of landslide pipeline.The main research contents are as follows:(1)Aiming at the large displacement deformation of buried pipeline under the action of transverse landslide,a mechanical model based on the axial deformation of pipeline and the shear action of soil spring outside the landslide is established,and the analytical calculation method for the deformation of pipeline outside the landslide is studied.The effects of axial stress and soil spring on the deformation of pipeline outside the landslide at different elastic-plastic stages are analyzed.Through the deformation coordination equation at the boundary of landslide,the axial strain and bending strain of pipeline are obtained by iterative calculation method.At the same time,the stress-strain analysis method of buried pipeline under longitudinal landslide is studied.Compared with the finite element method,it is verified that the method has good accuracy and engineering applicability.(2)In view of the deficiency that it is difficult to distinguish the variation law of landslide and pipeline parameters on pipeline strain by analytical method,a numerical calculation model of buried pipeline in landslide area based on shell element and nonlinear soil spring is established,the deformation distribution characteristics of landslide pipeline based on multi factors are studied,and the effects of sliding slope width,buried depth,soil ultimate resistance,diameter thickness ratio and internal pressure on pipeline vertical displacement,axial strain and bending strain are obtained.(3)According to the above analytical and finite element methods,the plastic deformation position of the pipeline under the action of landslide is determined,the software and hardware configuration of the pipeline strain monitoring scheme is designed and determined,the actual site is visited and investigated,and the on-site installation of the pipeline strain monitoring system is completed.Aiming at the problem of data noise interference and fluctuation caused by multi-path error in the transmission of pipeline strain monitoring data,a data noise reduction model based on variance compensation adaptive Kalman filter is studied.The processing results of field data show that the model has good noise reduction effect.The design criterion of landslide pipeline based on limit strain is studied,and then the early warning interval of pipeline strain monitoring is designed.