It is generally accepted that railway ballast has a finite life. With use it becomes abraded and fouled, and is eventually cleaned and replaced or often renewed completely. However, much of our experience regarding the gradual deterioration of railway ballast is based on aggregates (e.g. limestone) that are mineralogically more susceptible to damage than the high quality granite used on a modern railway. Building on previous work, this project will investigate the extent of, and the reasons for, the apparent deterioration due to traffic and tamping in the mechanical properties of ballast of different mineralogies (granite and limestone), fresh and used ballast (from sites and from the laboratory rigs), cleaned ballast (from the ballast cleaning train) and modified cleaned ballast, by means of
a. monotonic and cyclic triaxial tests on full size and scaled ballasts
b. rig tests at Southampton and Nottingham, using full size ballast
c. field data of ongoing settlements and lateral movements before and after renewals where no additional interventions (apart from reballasting and track renewal) have been carried out, from the T2F field study sites
d. numerical discrete element analysis (DEM) to explore the fundamental mechanisms responsible for any deterioration in ballast performance (e.g. attrition, loss of surface roughness, increasing particle roundness, change in PSD)
The data and analyses will be incorporated into integrated T2F models for improved track performance prediction and maintenance planning.
The ’Mechanical properties of re-used ballast’ project is part TRACK TO THE FUTURE (T2F) a major five-year, £8M research programme, funded by EPSRC, industry and the Universities of Southampton, Birmingham, Huddersfield and Nottingham. Its aim and vision is to support the development of railway track systems that are efficient in terms of embodied carbon, materials use and cost; robust in requiring little maintenance; and unintrusive in producing little noise. It will address this aim through three interlinked Research Challenges RC.
TRACK4LIFE (RC1): low-maintenance, long-life track systems with optimised material use, through
• developing, and demonstrating the effectiveness of, new track forms or components and promising interventions e.g. under-sleeper pads and random fibre ballast reinforcement (1A)
• developing an understanding of the relationships between the key measurable parameters of track stiffness and track settlement, and the key performance parameter of geometrical standard deviation, taking into account the interactions with rail geometry and vehicle dynamics (1B), and
• extending the life of ballast by reducing or eliminating the factors leading to its degradation, assessing the feasibility of design for the degraded state and facilitating re-use rather than downcycling or disposal (1C).
DESIGNER CROSSINGS AND TRANSITIONS (RC2): crossings and transitions that optimise the behaviour of the vehicles traversing them, thereby minimising damage. This will be achieved by developing new understandings of the highly complex interactions between switch and crossing geometry, sub-base support, wheel profile and vehicle dynamics, including the effects of varying the support stiffness through the crossing or transition; and combining them with the potential of modern manufacturing methods to provide a tuned variation in geometry and materials properties.
NOISE-LESS TRACK (RC3): an integrated approach to designing a low-noise, low-vibration track consistent with reduced whole life costs and maintenance needs. Track is the main source of railway rolling noise and has a key role in vibration transmission into the ground. Noise is increasingly cited as the main objection to the expansion, reopening or construction of railways. However, design changes are usually driven by other concerns with the implications for noise and vibration considered as secondary effects.
Applications for this PhD research project are accepted on a rolling basis and we therefore advise you to apply early if you are interested. To make your application please go to: http://www.southampton.ac.uk/engineering/postgraduate/research_degrees/apply.page
If you wish to discuss any details of the project informally, please contact Dr Antonis Zervos, Infrastructure research group, Email: A.Zervos@soton.ac.uk
, Tel: +44 (0) 2380 59 2459.
This project is being run in participation with the EPSRC Centre for Doctoral Training in Sustainable Infrastructure Systems (http://www.cdt-sis.soton.ac.uk/
). For details of our 4 Year PhD programme and further projects, please see http://www.findaphd.com/search/PhdDetails.aspx?CAID=2477
Visit our Postgraduate Research Opportunities Afternoon to find out more about Postgraduate Research study within the Faculty of Engineering and the Environment: http://www.southampton.ac.uk/engineering/news/events/2016/02/03-discover-your-future.page