Evaluation of the effects of pipe-soil interaction on the stress based design of buried pipelines using advanced numerical modeling
Thermal stress analysis of the buried pipeline is an integral part of pipeline design and integrity analysis. Pipeline design code (e.g. CSA Z662) provides guidance on the thermal stress analysis of restrained and unrestrained pipe sections. However, a buried pipeline bend is more likely to be partially restrained, as the pipe is free to expand longitudinally, but the expansion is restrained by the pipe-soil interaction. No clear guidance is provided in the design code for a partially restrained condition. Besides, circumferential stresses induced by thermal expansion is not considered in the design code. One of the major challenges in the thermal stress analysis of buried pipelines is modeling the soil as the engineering properties of soil depend on a wide range of factors. The complex deformation characteristics of the buried pipeline in response to the thermal expansion induced in-plane and out-of-plane bending moments are significantly affected by pipe-soil interaction. The proposed research will investigate the gaps in the design code through advanced finite element analysis. The deliverables of this project will not only help industries, e.g. Northern Crescent, to improve design and integrity assessment of buried pipelines but also the outcomes can be useful to update the design codes.