Fault rupture is one of the main hazards for continuous buried pipelines and the problem is often investigated experimentally and numerically. While experimental data exists for pipeline crossing strike-slip and normal fault, limited experimental work is available for pipeline crossing reverse faults. This paper presents results from a series of tests investigating the behaviour of continuous buried pipeline subjected to reverse fault motion. A new experimental setup for physical modelling of pipeline crossing reverse fault is developed and described. Scaling laws and non-dimensional groups are derived and subsequently used to analyse the test results. Three-dimensional Finite Element (3D FE) analysis is also carried out using ABAQUS to investigate the pipeline response to reverse faults and to simulate the experiments. Finally, practical implications of the study are discussed.
Pipelines are reliable and economical means of transporting water, oil, gas, sewage and other
fluids. They are generally referred to as lifelines since they play a pivotal role in running a
nation?s industries, services, and economy. Thus, it is essential that they remain operational at
all times. Pipeline systems are located over large geographical regions and they are generally
buried below ground for safety, economic, environmental and aesthetic reasons. As a result,
they are exposed to a wide variety of soil profiles and hazards caused by earthquakes.
Past earthquake-related pipeline damage highlighted the vulnerability of buried pipelines to
Permanent Ground Deformations (PGD) caused by earthquakes. Different types of pipeline
failure modes such as joint failure, tension failure, beam buckling, and local buckling failure
have been observed in past earthquakes. Recent earthquakes showed that unsatisfactory
performance of buried pipelines is still observed. As a result, further research is required in this
subject. This thesis aims to study the response of buried continuous pipelines to faulting through
physical model tests and numerical analysis.
In this Ph.D. research, relevant scaling laws and non-dimensional groups for buried continuous
pipelines crossing active faults are derived by using Buckingham-À theorem and governing
differential equations. The physical meaning of these non-dimensional groups and their
practical ranges are presented. A new physical model test setup of buried continuous pipelines
crossing strike-slip faults was developed considering the non-dimensional groups and scaling
laws. The working principle of the test setup and sensors used in the tests are also presented.
Furthermore, a simple and scalable end connector for physical modeling based on the equivalent
end springs approach in numerical modeling is proposed. The performance of the proposed end
connector is assessed via physical model tests and numerical analysis. In addition, a new
mitigation technique ? using tyre derived aggregate (TDA) as backfill material at the vicinity
of fault crossings- is proposed. The performance of the proposed mitigation method is assessed
through physical model tests. The effects of trench shapes, trench dimensions and tyre-chip
content in the backfill on pipeline performance are also investigated. Finally, three-dimensional
(3D) Finite Element (FE) models of buried continuous pipelines crossing active faults are
developed and these models are validated through case studies, experimental studies and
analytical methods. By using the calibrated 3D FE models, a parametric study is carried out to
investigate the effects of different pipe end conditions on the behaviour of buried continuous
pipelines crossing strike-slip faults and to investigate the effects of non-dimensional groups on
pipeline response to strike-slip faulting.
The research study shows that the newly developed experiment setup is a reliable tool to capture
the behaviour of buried continuous pipelines crossing strike-slip faults and to investigate the
physics behind the soil-pipe interaction problem under faulting. Furthermore, the proposed end
connector is capable of simulating pipe end conditions more realistically compared to
conventional pipe end conditions used in earlier experimental studies. Finally, the proposed
mitigation technique ?using TDA as backfill material at the vicinity of fault crossings- is an
effective way of protection that reduces peak bending and axial strains within the buried
continuous pipelines crossing active faults.