Lateral global buckling response of submarine pipelines considering soil spatial variability

Submarine pipelines are prone to global buckling under high-temperature and high-pressure conditions, where soil resistance plays a critical role. In shallow-water areas such as the Bohai Sea, seabed conditions can vary considerably along the pipeline route, whereas conventional studies commonly assume uniform soil resistance and neglect such spatial variability. To address this limitation, an elastoplastic 3D-Explicit finite element model incorporating non-uniform soil resistance is established by assigning discretized friction coefficients along the pipeline route and validated against thermal buckling model tests. Based on this model, the effects of soil resistance distribution patterns on buckling modes and evolution are systematically investigated, and the differences in global buckling response between uniform and non-uniform soil resistance cases are compared, while the influence of soil spatial variability on buckling amplitude and critical axial force is quantified. Results show that soil resistance distribution significantly influences the buckling mode. Under non-uniform soil resistance, the triggering of pipeline buckling exhibits spatial variability and temporal sequence characteristics. In addition, soil spatial variability significantly affects the buckling response: within the investigated cases, a 0.1 increase in the coefficient of variation raises buckling amplitude by approximately 35% and reduces the critical axial force by about 12% on average. These findings link sequential buckling characteristics to practical mitigation by guiding the identification of buckle-prone zones and the targeted deployment of buckle-initiation or reinforcement measures under spatially variable seabed conditions.