As typical linear engineering for long-distance transportation, buried oil/gas pipelines face potential threats and substantial damage from landslides along their routes. Focusing on the large-deformation responses of buried pipelines within landslide zones and at their boundaries, this study establishes a mechanical-physical model for pipelines traversing landslides. By comprehensively incorporating multiple factors such as nonuniform landslide displacement, intersection angle between landslide boundary and pipeline, pipe-end boundary conditions, and nonlinear pipe-soil interaction, the model introduces an equivalent fault at the landslide boundary and equivalent spring boundaries at the pipe ends. A 3D nonlinear finite element model for buried pipelines traversing landslides is established and validated through case studies to ensure accuracy. Extensive numerical simulations based on the proposed model are performed to deeply investigate potential failure modes and the sensitivity of landslide parameters for buried steel pipelines crossing transverse landslides. Results indicate that the pipeline failure modes include tensile fracture, buckling failure, lateral displacement, and bending deformation. The maximum pipeline strain is positively correlated with landslide displacement magnitude and inclination angle and exhibits low sensitivity to landslide width under fixed displacement. The intersection angle between the landslide boundary sliding direction and pipeline axis critically influences the mechanical behavior near the boundaries, and its recommended value is 75°. This work provides a finite element method for the safety assessment of buried pipelines transversing landslides, advancing the current understanding of failure mechanisms and large-deformation influences.