Deformation and stress analysis of the buried pipeline in formation collapse region

The effect of the formation collapse on the safety of the buried pipeline is studied respectively by using the Winkler foundation beam model and the ideal elastic-plastic foundation beam model.The mechanics analysis model of the interaction between pipeline and soil with the large geometric deformation is established,and it is solved by applying nonlinear theory.The analytical results show that,comparing with the Winkler foundation beam model,the ideal elastic-plastic foundation beam model is closer to the practice of the pipeline,but the Winkler model is simple and therefore it is convenient to engineering application;the critical pipeline lengths in the collapse area calculated respectively by using the two model are different,the error between them increases with the increase of the yield strength of the pipeline material,and therefore the Winkler model should be used for calculating the critical pipeline length when the yield strength of the pipeline material is less;the errors of the pipeline deformation and stress calculated respectively by using the two model are less when the critical pipeline length in the collapse area is less,so the Winkler model should be used for calculating the deformation and stress in order to simplify the calculation;the effect of soil spring stiffness on the analytical results of pipeline can be neglected when the elastic-plasticity model is used,but the effect of soil spring stiffness should be considered when the Winkler model is used.