A numerical investigation on the axial pullout tests of buried pipes

Salami, Adeniyi (2022) A numerical investigation on the axial pullout tests of buried pipes. Masters thesis, Memorial University of Newfoundland.

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Abstract

Pipelines may unavoidably be routed through areas susceptible to ground movement. The reliability of pipelines comes into question during events of ground movements due to generated loads due to ground movements. It is therefore imperative to accurately predict the loads generated to enable the proper design of pipelines. Many researchers have produced high-quality data from tests that idealize real-life conditions by pulling pipe through fixed soil, although in the actual event of ground movement, unstable soil moves away from stable soil that fixes the pipe. This study develops a finite element modeling technique to simulate laboratory conditions by pulling pipe through fixed soil, and the real-life condition is simulated by pulling soil while pipe is fixed in place. The finite element technique is also used to investigate the effect of pipe length, diameter, burial depth, and internal pressure for both steel and polyethylene pipes. The study reveals that short steel pipelines beginning from 1 m length developed a higher peak pull-out force for pipe pulling simulation compared to soil pulling simulation, this behaviour changes for longer steel pipelines from 6.5 m where soil pulling simulation predicts a higher peak pull-out force compared to pipe pulling simulation. Polyethylene pipelines simulated for pipe pulling predict higher peak pull-out forces of varying percentages with increase in length when compared to soil pulling. The effect of increase in soil width is not significant in the prediction of pull-out forces for both simulations. An increase in diameter and burial depth also increases pull-out forces for both simulations. Increase in pressure is not significant in the development of pull-out forces for steel pipelines while in polyethylene pipelines an increase in pressure increases development of pull-out forces.

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