Predictive Method for Pipeline Strain Demand Subject to Permanent Ground Displacements with Internal Pressure & Temperature

Abstract

Pipelines subject to ground deformations generated by geohazard loads carry high importance on pipeline analysis, design, and assessment due to risk of structural damage or failure. Additionally, internal pressure and temperature variation within an operating pipe induce additional strains in combination with pipe strains generated by ground displacement. In this thesis, these additional loads are implemented in several hypothetical finite element analysis (FEA) simulations to assess the impact of internal pressure and temperature change for pipes subject to ground displacement in soils of varying stiffnesses. Furthermore, an enhanced predictive method is proposed founded upon methods employed by Zheng et al. (2021b) to predict pipeline behaviour subject to permanent ground displacement, while considering effects of internal pressure and temperature variation. The proposed method accounts for the initial thermal strains, and biaxial stress state in the pipe due to hoop stress generated by internal pressure. These additional strains are considered within the expressions of internal axial force and bending moment, derived based on the actual stress distribution on the pipes’ cross-section. The accuracy of the proposed method is validated against the finite element method (FEM) with respect to results of pipe strain and deformation using several indicative case studies. This research provides a new effective method of incorporating temperature and internal pressure loads on the inelastic strain demand of pipelines subject to permanent ground displacement of varying types, magnitudes, and directions.