Numerical modeling of oil pipeline bending caused by migrating pingos in the permafrost on the northern Qinghai-Tibet Plateau

Abstract：Migrating pingos are developed along active faults in the permafrost area on the northern Qinghai-Tibet Plateau. They may destruct oil pipelines, bridges and culverts in the area. 3D nonlinear finite-element numerical modeling is performed of the destruction of oil pipelines by using the ANSYS finite element general procedure. It reveals the stress field, displacement field and plastic deformation caused by freezing and expansion of the migrating pingo and presents the oil pipe bending deformation caused by the migrating pingo and stress distribution. Bending of pipes produces compressive stresses of -515 MPa and tensional stress of 520 MPa inside the pipes, which exceed the yield strength of 450 MPa for the pipes, thus leading to plastic deformation and destruction of the buried oil pipes. The modeling of oil pipeline bending caused by the migrating pingo may provide an important basis for pipeline engineering design and prevention and control of geohazards produced by the migrating pingos in the study area. Finally measures of prevention and control are proposed.