Postbuckling of Buried Geodesically Stiffened Pipelines under Combined External Pressure and Axial Compression

Abstract

Underground pipelines for transportation and commercial usage are in high demand for meeting both sustainable population and economic growth in well-established metropolitan areas. This study presents the postbuckling analysis of buried geodesically stiffened pipelines of finite length subjected to combined loading of external pressure and axial compression. The pipeline, treated as a shell structure, is embedded in soil, and the pipe–soil interactions are modeled as a Pasternak elastic foundation. The governing equations are based on Reddy’s higher order shear deformation shell theory with the von Kármán-Donnell type of kinematic nonlinearity. Nonlinear prebuckling deformation and initial geometric imperfection of the liner are both taken into account to investigate the buckling and postbuckling behavior of geodesically stiffened cylindrical pipes under combined loading cases. The effect of stiffeners (e.g., geodesic, axial, and ring stiffeners) is evaluated by a smeared approach, and a singular perturbation technique is employed to determine the interactive buckling loads and postbuckling equilibrium paths. Numerical postbuckling analysis is performed of perfect or imperfect, stiffened or unstiffened pipes with different liner parameters under different load-proportional values. The present study can facilitate design analysis and optimization of stiffened pipes, and it can be used to develop remedial schemes (e.g., design of thickening pipe walls and stiffening ribs) for underground pipes against instability during service and during the pipe-jacking process.