Investigation of Tectonic Effects on Pipeline Stabilty

Pipelines make an important group of structures called lifelines, as they support conducting water, oil and gas essential for life. The large and short duration deformations of the ground and fault are among the most serious geological factors that affect pipelines’ performance and may lead to large asymmetric deformations on both sides of a given pipe. Such fault movements are triggered by ground motions arising from an earthquake and tsunami, natural river meandering or man-made mining activities. Observed damages of pipelines in the past have shown that pipelines (especially the buried ones) are sensitive to permanent ground deformations (PGD's) resulting in bending, buckling and cracking of the pipe. Heavy damages resulting from the rupture of buried pipes have been reported all around the world including Australia. For instance, the Newcastle earthquake alone claimed $4B damage of infrastructure of which a large portion is due to buried pipes. The Ian San Salvador earthquake in 2001 resulted in a loss of $21M, damaging the city water pipelines.

One major limitation of previous studies is that the structural geology aspect, primarily modelling the effect of strike and dip angle and the effect of interlocking arising from asymmetrical bed angles are not modelled. This results in overdesign of the pipe, as interlocking of soil grains naturally prevents large deformation of tectonic plates. A multidisciplinary approach needs to be undertaken in this research, where the non-linear plastic hardening-softening behaviour of the surrounding soil is modelled accurately. Although a number of research works have been undertaken on the pipeline stability issues, much of them have modelled the soil as elastic springs, which is not realistic.

To date, no plasticity-based soil models have been used to represent the soil behaviour in the fault zone, hence a rigorous soil-structure interaction model needs to be developed. Computer simulations will be carried out using world class CQU-HPC facilities within continuum and discrete finite element methods. Recognition of very large fault movements or high pipe strain requires exploring other modelling options such as the Coupled Eulerian Lagrangian (CEL) approach as well as particle-based finite element methods with suitable material subroutines developed in Fortran and Python. Extensive parametric studies are planned, not limited to pipe geometry, internal pressure and soil material properties. Preventive measures such as using a textured Pipe, ground anchoring using helical piles etc will be modelled and their effectiveness.
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The project is suitable for civil engineers with interests in soil mechanics, numerical modelling and geotechnical engineering. Engineering geologists with some numerical modelling experience or experience in using finite element software are also encouraged to apply