Grant: Discovery Grants Program - Individual

The structural integrity of buried pipelines is often compromised due to distress from various sources, including operational pressure, ground loads, and wall defects. Loads from the ground movements were reported to be a major cause of pipeline failure. The effects of the wall defects and ground loads must be rationally considered during the design and fitness-for-service assessment. The current design guidelines recommend the method of beam-on-spring analysis to assess the pipeline subject to ground movement. The recommended spring parameters were developed based on analysis and tests conducted under idealized conditions. For example, analysis and tests were conducted under plane strain conditions to determine the lateral spring forces. Besides, pipe segments were pulled against a static soil mass during the tests to investigate behavior under relative displacements. However, soil mass often moves against static pipes in the field. Our preliminary study reveals that the ground load on the pipe due to soil movement differs from those observed by pulling a pipe through static soil. There is a lack of a database on the behavior of pipes under a moving soil mass and a method to account for the effects in pipeline assessment. The long-term objective of the research program is to develop novel methods for buried energy transmission pipelines to account for the ground loads rationally and assess the structural stability against geohazards. The short-term objectives are to address the knowledge gaps related to soil-pipe interaction, crack propagation, and uncertainties in the parameters: 1) develop pipe-soil interaction models for ground movements in various directions; 2) apply fracture mechanics to investigate crack propagation leading to structural failure; and 3) develop reliability-based pipeline integrity assessment methods to account for uncertainties. Full-scale buried pipe tests will be conducted using the new test facility at Memorial University to investigate the pipe responses under various buried conditions. Finite element and discrete element modeling techniques will be employed to investigate the observed pipe behavior and the mechanism of soil particle movements contributing to the pipe responses. Based on understanding the soil-pipe interaction, realistic spring parameters will be determined. Then, the structural strength of the pipes subject to ground movements will be assessed using fracture mechanics. Finally, machine-learning models will be developed for reliability-based assessment of pipelines considering the uncertainty of the soil and pipe parameters. This study will generate a unique database of the responses of pipes against a moving soil mass and contribute to developing new guidelines for the economical and safe design of pipelines. The developed technology would benefit future clean (hydrogen) energy transportation via pipelines. Nine HQP will be trained in areas needed for maintaining infrastructure integrity.