Pipe-soil Interaction and Soil Consolidation with Energy Pipelines

NADERI Ali*, DENG Ruoqi*, YU Deli (TC Energy), KANIA Richard (TC Energy), LI LePing (2020). 

Pipe stress and deflection during an integrity dig. Proceedings of the 13th International Pipeline Conference, Calgary, Canada, September 28 – October 2, 2020

Full-length paper and virtual video presentation: Paper from ASME Digital Collection or https://doi.org/10.1115/IPC2020-9269, V001T03A004, 8 pages.

* Indicates PhD students at the University of Calgary

Biomechanics Publications by LePing Li Monograph and Book Chapters

Pipe Stress and Deflection During an Integrity Dig

Abstract

https://doi.org/10.1115/IPC2020-9269

During a pipeline excavation, additional pipe stress and deflection can be produced due to altered soil support beneath the exposed pipe, which might bring in additional integrity concerns for the pipe under assessment. Classical beam theories and soil-spring modeling are inadequate for the complex pipe-soil interactions and boundary conditions. The objective of the present study was to develop a computational model that can be used to predict pipe stress and deflection during an integrity dig. The pipe-soil interaction was modeled with 3D elements using surface-to-surface contact approximation in ABAQUS. The pipe was assumed to be initially buried, then exposed for 12, 20, 30 and 34 m subsequently to mimic a buried pipeline under step-by-step excavation. The results indicated that the depth of soil support is a dominant factor for the pipe stress and deflection during an integrity excavation, which has not been previously investigated. Significant axial stress and strain in the longitudinal direction were produced by excavation, which may increase the risk of failure for the pipe that is suspected of circumferential defects. Furthermore, nonuniform soil support could cause substantial pipe deflections and stresses that may trigger an integrity dig. The model may be used to estimate the pipe stress and deflection prior to an integrity dig based on the soil conditions.

Keywords: pipe-soil interaction, soil consolidation, stress analysis, finite element analysis, buried gas pipeline