Axial strain capacity of grouted sleeve repairs: A numerical investigation of critical design factors

While grouted sleeves are widely used to repair localized damage in pipelines, their capability to minimize geohazard-induced strains and resist slippage and pull-out forces during service is relatively less studied. In this research, finite element analysis (FEA) is employed to explore how grouted sleeve repair systems respond to axial strain in defective pipelines, emphasizing the role of key design parameters and their interactions. The analysis systematically varies these parameters to understand their influence on load transfer mechanisms and strain profiles. Findings show that repair length and grout thickness must be carefully optimized to reduce axial strain effectively, as further increases offer limited or even negative returns. Increasing grout stiffness contributes to lower strain levels, and the sleeve’s stiffness and thickness are major factors affecting overall repair performance. A key contribution of this study is the adoption and application of a strain-based failure criterion, enabling prediction of the limit state behavior under axial loading and guiding design limits for repair effectiveness. Simulations beyond service-level conditions demonstrate that all repaired models outperform the unrepaired pipe, with strain capacity improving as grout and sleeve parameters are optimized. However, these benefits plateau or decline beyond certain values, confirming the existence of optimal ranges for effective repair design. The study offers practical guidance for improving the design of grouted sleeve repairs, and it also provides a foundation for future experimental validation and ongoing numerical studies aimed at further quantifying system performance and supporting broader field implementation.