Behaviour of small-diameter buried steel pipes subjected to axial ground movement

Andersen, Darren (2024) Behaviour of small-diameter buried steel pipes subjected to axial ground movement. Masters thesis, Memorial University of Newfoundland.

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Abstract

Small-diameter steel pipes are often used to distribute gas to residential homes. These pipelines sometimes run through landslide-prone areas, highlighting a need to understand their response to ground movements. To investigate the axial behaviour of pipe subjected to ground movements, previous studies were conducted in the laboratory by pulling a pipe through a static soil mass. However, in real landslides, a soil mass moves while the pipe is restrained in stable ground. In this regard, a test facility was designed at Memorial University of Newfoundland where a soil mass can move against a pipe restrained on one end, simulating the condition expected during ground displacement. This thesis presents results for steel pipes of 26.7–, 60.3–, and 114.3 mm diameters subjected to axial ground movements using the test facility. The stop-start cycles during testing investigated the effects of intermittent ground movements on the axial soil force on pipes. Pipe axial force, axial strain, and tank displacement were recorded during the tests. Results showed the dimensionless axial peak forces were higher during soil pulling than those from pipe pulling available in literature. No reduction of axial force was found during the intervals of subsequent pulling. However, peak axial forces reduced with unloading-reloading cycles that developed at relatively reduced soil box displacement. Measurements from the fibre-optic sensor attached along the pipe length showed negligible axial strain, and thus elongation, indicating that the pipe behaves as a rigid body. Finally, the applicability of existing design guidelines was evaluated by performing beam-on-spring analysis to simulate full-scale laboratory experiments. The study revealed that earth pressure coefficients recommended in the design guidelines are incapable of accurately predicting the maximum axial soil resistance measured during the full-scale tests. K-values for the tests were then back-calculated using the design equation and applied to the beam-on-spring analysis to simulate the test results.

Item Type: Thesis (Masters)
URI: http://research.library.mun.ca/id/eprint/16520
Item ID: 16520
Additional Information: Includes bibliographical references -- Restricted until May 14, 2025
Keywords: buried pipe, ground movement, axial, strain
Department(s): Engineering and Applied Science, Faculty of
Date: May 2024
Date Type: Submission

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