Experimental and numerical modelling of global buckling of underground pipelines due to high pressure and temperature

Abstract

Pipelines transporting oil and natural gas may develop substantial compressive forces due to high temperature and pressure of the fluid content. Such compressive forces may cause vertical (upheaval) buckling of the pipeline. The development of upheaval buckling due to thermal expansion may pose a major threat to the structural integrity, safety and operability of pipelines. This paper describes a series of physical model tests in order to investigate the uplift behavior of buried pipelines. The experiments investigate the resistance force during vertical pipe pullout for varying pipe geometries, embedment depths and soil properties. Two types of sand are considered, a medium dense sand exhibiting dilative behavior, and a loose sand exhibiting contractive behavior. Furthermore, numerical analyses are conducted to simulate the above experiments and to validate the numerical models. The elastoplastic Mohr-Coulomb constitutive model with hardening-softening behavior, dependent on both the plastic shear strain and the confining stress, is utilized for simulating the behavior of sand. Representative results from the validation process of the numerical model are presented and compared with experimental measurements. Finally, some preliminary analyses of the behavior of buried pipelines in upheaval buckling due to high temperature change are presented. © 2019, National Technical University of Athens. All rights reserved.