Numerical modelling of a railway ballast with a heterogeneous medium

Author: Dalton Rieck

Rieck, Dalton, 2019 Numerical modelling of a railway ballast with a heterogeneous medium, Flinders University, College of Science and Engineering

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The railway industry is another public and private infrastructure component that is looking to utilise new ways to improve and increase capacity, with the aim of improving transportation conditions for consumers into the future. As a result, many studies are being conducted in modelling various engineering components.

In this particular context, transport engineers are looking to improve the overall capacity of high-speed train lines. This will provide faster speed and higher capacity alternatives in line with the technological growth and development of these trains. Recent tests have demonstrated that the capacity exists for trains to exceed present limits, but that the system would not yet support such a capacity. When in close proximity to train lines, as is common in highly urbanised environments throughout the world that have significant train transportation demands, nearby infrastructure can become significantly damaged by wave propagation as this capacity and demand slowly increases in line with population growth.

Studies are beginning to examine the various components of a train-line under stress, and how we can come to better conclusions regarding the behaviour of line components in both the long and short term. The model that I have conducted testing with has been developed in an attempt to gain a greater understanding of ballast behaviour in particular, and how the impacts of wave propagation can be mitigated.

The ballast behaviour will be analysed through the implementation of a 3D spectral element model (SEM) with a perfectly matched layer (PML), allowing for simulation of ballast layer properties and loading conditions. The idea was to monitor different sensors to understand how the heterogeneous stress field fluctuates, and the impact this has on heterogeneous modelling cases compared to homogeneous modelling cases. The SEM model has been constructed with numerical underpinning, and has been tested via supercomputing clusters accessed remotely in Paris.

It will assist future construction methods and provide grounding for greater potential forecasting of damaging impact to infrastructure by improving our understanding of capacity requirements, and allowing greater conceptualisation of how we can design to those requirements.

Keywords: numerical, modelling, railway, SEM, geotechnical

Subject: Engineering thesis

Thesis type: Masters
Completed: 2019
School: College of Science and Engineering
Supervisor: Hongyu Qin