An elastoplastic semi-analytical method to analyze the plastic mechanical behavior of buried pipelines under landslides considering operating loads

An elastoplastic semi-analytical method is proposed to deal with the plastic mechanical behavior of buried pipelines subjecting to landslides based on the plane stress condition, considering the inner pressure and the temperature variation. According to the incremental theory of plasticity, the longitudinal, radial and hoop plastic strains are expressed as the corresponding equations that contain the longitudinal and hoop stresses. Considering the effect of the inner pressure and the temperature variation, the longitudinal stress is derived based on the elastoplastic-beam theory, and then the axial force can be determined based on the relation of the internal force and the stress. Combining the differential equation and the boundary condition, the transverse horizontal displacement, the bending strain, axial strain can be obtained. To verify the proposed model, the comparison of the obtained results from the proposed method and the finite element method is performed, with minor deviations of within 5.4%. Additionally, the effects of the inner pressure and the temperature variation on the strain and displacement of pipelines are investigated through parametric studies. The results show that the plastic deformation and strain are much larger when neglecting operating loads; the pipeline develops mainly the longitudinal and radial plastic deformations instead of the hoop plastic deformation.