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Innovative use of Geothermal Piles as heat storage to enhance Embankment Performance (IGPEP)

  • Supervisors: Dr Anthony Leung (University of Dundee), Prof Simon Wheeler (University of Glasgow)
  • Sponsoring company: Scottish Road Research Board (SRRB), Transport Scotland
  • PhD student: Davide Vitali

Infrastructure embankments/slopes make up a huge proportion of the UK transport network. Their stability, and hence engineering sustainability, are largely controlled by the amount of negative pore-water pressure (or suction) developed in unsaturated soils. In temperate European climates, the season of peak suction developed in slopes (summer/dry season) is out of phase with the season of peak suction demand for maintaining slope stability (winter/wet season). This lag is becoming more severe under the impacts of climate change, as evidenced by the increasing intense rain received over the last 20 years.

Given that existing and new-build infrastructure embankments will be in use for at least 50 years, there is an urgent need to seek sustainable engineering solutions to narrow the lag down – to preserve/increase suction and hence slope stability in winter time – so as to adapt to the effects of climate-change. Whilst installing a row of discretely-spaced piles at the mid-height of slope has been a common method for slope stabilisation, one novel approach that could exploit renewable energy source is to modify the piles for solar energy storage, referred to as geothermal piles. It is to use the geothermal piles as storage of surplus solar heat in summer for evaporating soil moisture, which in turn leads to increase in soil suction and slope stability in winter. The aim of the project is to explore the effectiveness of using this mechanism to improve the stability of infrastructure slopes. To investigate the effects of pile heating on the soil water regime, greater understanding on the water-heat-vapour flow mechanism(s) in unsaturated soil will be developed.

The outcome of the research will be to provide a high-quality dataset and physical evidence (through predominantly centrifuge modelling) to justify the use of geothermal piles for enhancing embankment performance under the threat of climate change. Greater understanding gained on water-heat-vapour flow mechanism in unsaturated soil will help to improve the numerical modelling of the simultaneous events of precipitation and evaporation at soil-atmosphere boundary.