Numerical Simulation of Buckling Behavior of Steel Frame-Reinforced Polyethylene Pipelines Under Reverse Faults with Different Inclination Angles

Abstract

Buried steel frame-reinforced polyethylene (SRPE) pipelines are vulnerable to bending-compression buckling, sectional distortion, and tensile rupture when crossing reverse faults. Nevertheless, their multi-mode failure mechanisms and strain evaluation frameworks have not been systematically clarified. Given this challenge, a three-dimensional nonlinear finite element model considering pipe–soil contact, material elasto-plasticity, and large deformation is established in this study to investigate the deformation characteristics, strain evolution, and buckling performance of SRPE pipelines under reverse fault inclination angles from 0° to 150°. The effects of internal pressure, steel frame diameter, and soil properties on pipeline mechanical behavior are analyzed, with the results being compared with the strain limits specified in the GB 50470-2017, CSA Z662-2023, and EN 13476-3 standards. The pipeline is subjected to a three-stage failure process involving local compressive buckling, overall bending, and tensile necking. Notably, coupled bending-compression failure is typical at low inclination angles, while high angles are dominated by shear-tension coupling. Excessive internal pressure increases the local buckling and concentration of compressive strains. An increase in the steel frame diameter contributes to an effective improvement in the buckling resistance. When the soil has higher cohesion and stiffness, the critical buckling displacement becomes larger. The standard constant strain limits currently adopted do not account for the transition in failure mode arising from inclination control and are therefore overly conservative for SRPE pipelines. This study provides a theoretical foundation and quantitative reference for the seismic design and safety assessment of SRPE pipelines crossing reverse fault zones.