Thermal Upheaval Buckling of Buried Pipelines: Experimental Behavior and Numerical Modeling

Abstract

Pipelines transporting oil and natural gas may experience upheaval buckling due to substantial compressive forces induced by high temperature and pressure of the fluid content. Such upheaval buckling may pose a major threat to the structural integrity, safety, and operability of pipelines. This study presents results from a series of scaled physical model tests conducted to investigate the uplift behavior and upheaval buckling of buried pipelines. The first set of experiments investigated the resistance force during vertical pullout for different pipe geometries, embedment depths, and relative densities of sand. The second set of experiments investigated the development of global upheaval buckling due to high axial compression of a buried pipe. The study examined the effect of embedment depth on the buckling characteristics and the postbuckling behavior of the pipe. Numerical analyses simulated the experiments and validated the numerical models. A parametric investigation based on rigorous numerical simulations examined the effect of trench-base initial imperfection, internal pressure, and soil strength on the upheaval buckling resistance. The results showed that as the geometric imperfection amplitude increased and its distribution length decreased, the upheaval buckling resistance substantially decreased. Similarly, an increase of the internal pressure of the pipeline may significantly decrease upheaval buckling resistance.