Nonlinear Buckling Analysis On Buried Heating Pipelines

In recent years,urban central heating pipelines have developed rapidly in our conntry.At present,the non-compensating and cold installation directly buried heating-pipelines has widely used and it caused more axial pressure due to the,temperatural load which greatly increased the risk of the pipeline's vertical buckling.So it is very important to analyze the vertical buckling of buried heating pipelines.Firstly,based on the reserch results at home and abroad,the unfavorable loads and dangerous area of buried pipelines was clarified.Secondly,the three-dimensional finite element model was established considering of pipelines' initial imperfection and soil-pipe contact interaction.Numerical calculation was used to studied the pipelines' buckling failure included nonlinearity of material,geometry and contact.Finally,according to the simulated results,the buckling process was determined and the coupling effects between local deformation and vertical buckling was analyzed.The mechanism of vertical buckling failure was studied by analyzing the pipelines' plastic deformation development,the pipelines' stress redistribution and the weakening process of soil constraints.The influence of various factors such as the initial imperfections,cover depth,pipe diameters,wall thickness and soil parameters were discussed by the parametric analysis and thecorresponding protective measures were put forward according to the analysis results.