CDT-SIS-492: Investigating the long-term response of geogrid-reinforced ballast under realistic loading conditions
Dr M J Fernandes De Pinho Lopes
Prof W Powrie
No more applications being accepted
Competition Funded PhD Project (European/UK Students Only)
Railway transportation of both freight and people is key to reduce CO2 emissions significantly. There are several advantages of railway transportation; however, minimising track maintenance costs, and finding alternative materials and approaches to improve the performance of railway track is essential. Ballasted railway tracks have generally provided adequate resistance to movement while allowing adjustments in line and level to be made as required (primarily by or during tamping). As the intensity and volume of traffic on railways have increased, more and more maintenance of ballasted tracks has been required. This is disruptive and expensive; hence, more robust ballast and sub-base solutions are being sought.
Geogrids have been used successfully to reinforce and/or stabilise ballast. Geogrids provide confinement and limit lateral movement of particles, which in turn reduces vertical settlements. Nevertheless, geogrids cannot be used within the tamping area, as they would not survive the tamping process. There is some evidence that placing a geogrid at the base of a ballast layer can provide a stabilisation effect up to 0.30 m above or below that layer. If such benefits are confirmed in long-term loading relevant for railway applications, the geogrid reinforcement can be used to improve ballast performance and placed away from the tamping depth. This will allow the use of geogrids to reinforce railway ballast and thus increase the time between maintenance operations. Additionally, using geogrid layer(s) will also potentially enable specification of the requirements of ballast used in railways to be relaxed, contributing to more resilient and sustainable railway track solutions.
The aim of this project is to investigate the reinforcement and stabilising mechanics of geogrids placed within ballast for loading conditions relevant to railway applications. The research will utilise a variety of novel, state of the art techniques (e.g., imaging and sensors, element testing using full field image (DIC) analysis during shearing, full scale cyclic loading tests).
We are seeking a motivated candidate who has a strong background in Civil Engineering, namely geotechnics and/or soil reinforcement with geosynthetics.
If you wish to discuss any details of the project informally, please contact Dr. Margarida Fernandes de Pinho Lopes, Infrastructure research group, Email: [Email Address Removed], Tel: +44 (0) 2380 59 8363.
UK students: Full funding is available
EU students: Full funding may be available or a small top up from the student may be required, depending on the calibre of the student. Funding is competition based and the student must have at least a 2.1 degree or equivalent.
International students: A small amount of funding is available but the student must be largely self-funded. Funding is competition based and the student must have at least a 2.1 degree or equivalent.
For details of our 4 Year PhD programme and further projects, please see http://www.cdt-sis.soton.ac.uk/
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