Study on mechanical response of X80 pipeline under strike-slip fault action

Strike-slip fault misalignment can lead to stress concentration, fissure development, and slip instability in overlying soil layers, triggering geologic hazards such as surface displacement, landslides, and rock formation deformation, causing severe damage to buried infrastructure. In cross-regional energy transmission projects, stress concentration and deformation failure induced by fault movement in cross-fault buried pipelines critically threaten the safe transmission of oil and gas. As the scale of oil and gas pipeline construction in China expands, pipelines inevitably cross fault zones, increasing rupture risk and necessitating investigation of fault misalignment mechanisms and pipeline mechanical response. This study employs three-dimensional nonlinear finite element analysis to investigate the mechanical response of X80 buried pipelines under strike-slip fault action. A comprehensive pipe-soil interaction model incorporating the Ramberg-Osgood constitutive relationship and Mohr-Coulomb soil plasticity is developed using ABAQUS software. The research systematically examines the effects of fault displacement (0.5-2.5 m), pipeline wall thickness (18.4-32.1 mm), internal pressure (0-12 MPa), and pipe-soil friction coefficient (0.3-0.6) on pipeline stress and strain responses. Key findings include: (1) a characteristic bimodal von Mises stress distribution occurs at approximately ±20 m from the fault plane, with secondary peaks at ±10 m; (2) stress and strain increase nonlinearly with fault displacement, with diminishing increments as the material enters the plastic regime; (3) increasing wall thickness from 18.4 mm to 32.1 mm reduces maximum tensile strain by approximately 50 %; (4) internal pressure and friction coefficient effects are significant only below the 2 m fault displacement threshold. The results provide quantitative guidelines for wall thickness selection and protective measure implementation for cross-fault pipeline design, ensuring safe operation during service life.