Rooting for sustainable performance

Lead Research Organisation: Durham University
Department Name: Engineering


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.


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Description Results from this project demonstrate the potential of using natural vegetation to improve the stability of engineered slopes (transportation embankments and cuttings). The addition of plant roots improves the tensile strength of the soils these earth structures are constructed from and also remove water from the slopes through evapotranspiration. By carefully managing the vegetation present on a slope it may be possible to achieve more stable embankments without the use of expensive "hard" engineering solutions (such as concrete retaining walls). This reduces costs and has a lower environmental impact than traditional techniques.
Exploitation Route The findings from this work can be taken forward by conducting instrumented field trials on infrastructure sites. This would confirm the effectiveness of the techniques developed in real world conditions and provide insights into any challenges to implementation that may arise on working infrastructure.
Sectors Construction

Description EPSRC - Research Grant, Standard Research - NR1
Amount £218,232 (GBP)
Funding ID EP/R041903/1 
Organisation Engineering and Physical Sciences Research Council (EPSRC) 
Sector Public
Country United Kingdom
Start 04/2018 
End 04/2020
Description COST TU1202 Impacts of climate change on engineered slopes for infrastructure 
Organisation European Cooperation in Science and Technology (COST)
Country Belgium 
Sector Public 
PI Contribution Participation at slope stability workshops. Mentoring of early stage researchers
Collaborator Contribution Financial contribution from EU.
Impact Four sate of the art papers on slope stability and climate change published in QJEG&H. Numerous conference publications published by members of the network.
Start Year 2013
Description Schools Outreach (EDT Headstart) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Schools
Results and Impact Overall aim of the 4 day residential course is to encourage A level students to study STEM subjects at UK universities. As part of this course a lecture was given on geotechnical engineering and in particular the use of vegetation in the stabilisation of infrastructure slopes. Students attending the lecture engaged in a question and discussion session after the lecture. A number of the students declared an increased interest in the use of natural materials in engineering after the talk.
Year(s) Of Engagement Activity 2015,2016,2017