The environmental contamination due to the leakage of energy pipelines is a serious hazard to the public property and safety. Hence, any premature rupture should be dealt with in the design and the operating mode of steel pipes. A large amount of complexity is involved in the soil-pipe interactions that makes it so challenging to discover the physical boundary conditions (BC) applied to the buried pipelines during differential ground movements. Therefore, the most critical boundary conditions of buried pipes should be conceived based on the probable mechanism of soil-pipe interactions and considered in the experimental and analytical simulations of rupture. The focus of the current research is to address the critical boundary conditions that can trigger the rupture of underground wrinkled pipelines whilst being subjected to a monotonic increase of curvature.

Finite element (FE) simulation of a full-scale bending test on a pressurized X70 line pipe specimen conducted at the University of Alberta is implemented. Cumulative fracture criterion coupled with the equivalent plastic strain to fracture for X70 steel grade is fed into the analysis to predict the ductile crack formation in the pipe’s body. The FE model is verified by the experimental data and is used to study the critical soil-pipe interactions that provoke the rupture of buckled steel pipes on the tensile side of the cross-section under increasing bending curvature. The results of this study suggest that the pipelines which are restricted from axial displacements are extremely vulnerable to experience a rupture along their post-buckling loading path. And so are the pipelines in which tensile axial force is developed due to soil-pipe interactions, e.g. pipelines in arctic regions that are installed during the summer time.

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