Conical strain wedge model for nonlinear analysis of buried continuous pipelines under strike-slip fault movement

Fault displacements induce significant deformation in buried continuous pipelines, leading to failure modes such as local buckling, longitudinal cracking, or even complete rupture. Understanding these deformation mechanisms is essential for improving the safety and reliability of pipelines in fault zones. Existing beam-on-elastic-foundation models, though widely used in engineering practice, still have limitations in capturing the three-dimensional plastic deformation of soil, which directly reduces the accuracy in predictions of pipeline response. Based on soil flow-around failure under the lateral movement of deeply buried pipeline, the pipeline-soil contact force model is refined by incorporating three-dimensional soil plastic deformation. A conical strain wedge model for pipeline-soil interaction under strike-slip fault displacement is proposed in this study to explicitly consider the effects of soil nonlinear response and validated against finite element simulation results. The proposed analytical framework offers improved accuracy and computational efficiency in the predictions of soil reaction forces, pipeline deformation, and internal forces. The proposed conical strain wedge model is employed to systematically investigate the influence of key parameters on the performance of buried pipelines crossing strike-slip faults. Results demonstrate that fault displacement magnitude constitutes the dominant factor controlling both conical strain wedge development and pipeline deformation. Increased burial depth-to-diameter ratios are found to reduce the conical strain wedge zone, which subsequently enhances pipeline strain. Similarly, higher soil friction angles and soil cohesion reduce the conical soil wedge zone while simultaneously amplifying lateral deformation and strain in the pipeline.