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Details of Grant 

EPSRC Reference: EP/M020355/1
Title: Rooting for sustainable performance
Principal Investigator: Bengough, Professor AG
Other Investigators:
Muir Wood, Professor D Knappett, Dr JA
Researcher Co-Investigators:
Project Partners:
CH2M HILL Forest Research Highways England
London Underground Ltd Mott Macdonald Network Rail
Rail Safety & Standards Board Transport Research Laboratory (TRL) Ltd
Department: Civil Engineering
Organisation: University of Dundee
Scheme: Standard Research
Starts: 01 October 2015 Ends: 31 March 2020 Value (£): 639,895
EPSRC Research Topic Classifications:
Ground Engineering Soil science
EPSRC Industrial Sector Classifications:
Environment
Related Grants:
EP/M019713/1 EP/M020177/1 EP/M019527/1
Panel History:
Panel DatePanel NameOutcome
25 Feb 2015 Engineering Prioritisation Panel Meeting 25 February 2015 Announced
Summary on Grant Application Form
More frequent intense rainfall events, associated with climate change, increase the likelihood of shallow slope failures that lead to costly disruption of road and rail journeys, with risk to life and property. There have been recent slope failures adjacent to transport corridors in the UK, sometimes disrupting important road and rail routes for days. Vegetation has a stabilising effect on slopes: Plant root systems interlock with the soil, increasing its stiffness and strength. Uptake of water by root systems dries the soil profile, again increasing soil stiffness and strength. However, engineers need to be able to predict the combined root reinforcement and soil drying effects on slope stability, so that vegetation management can be used proactively to decrease the probability of slope failure. Vegetation has numerous benefits over conventional hard-engineering solutions, in terms of burying carbon in the soil, enhancing biodiversity, and improving the aesthetic quality of the environment for society.

This project will develop and test a quantitative coupled hydro-mechanical model for the in-service and ultimate-failure performance of slopes planted with vegetation. Rooted-soil represents an innovative sustainable construction material, with distinct mechanical and hydrological properties, that can be used in geotechnical systems. The model will be applicable to both slopes covered with natural vegetation and slopes where vegetation and soil have been chosen and managed according to engineering principles. The validated model will provide a clear framework for assessment and remediation of slopes with potential for reducing economic and carbon costs.

The model will be developed within a multi-scale continuum modelling framework. It will build on knowledge of the elemental components of the system, working from individual soil-root interaction, to continuum soil-root system, and to complete slope, incorporating spatial variability of materials. Modelling will be informed by X-ray CT imaging of the 3-D deformation of rooted soil undergoing shear, using the micro-VIS facility at the University of Southampton, and by field data from slopes containing established vegetation. Predictions of slope performance will be validated against scaled-slopes in the Dundee geotechnical centrifuge under different rainfall regimes. The geotechnical centrifuge enables the testing and monitoring of small-scale slopes containing roots at realistic stresses, which can be manipulated until the slopes ultimately fail.

Template guidelines will be produced for a manual of combinations of plant species, soils and management schemes for optimum performance of designed soil-plant systems suited to emerging climatic conditions. Example data will also be included to allow cost-benefit analyses when designing for slope improvement using vegetation. The potential to translate research findings into related areas will be investigated (e.g. river banks, sand dunes, flood embankments, agricultural and amenity systems). We will engage with an important group of Project Partners, representing key industrial sectors and infrastructure owners, to facilitate the rapid adoption of research findings.

Key Findings
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Organisation Website: http://www.dundee.ac.uk