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Details of Grant 

EPSRC Reference: EP/N03287X/1
Title: Climate-change effects on the performance of bioengineered clay fill embankments
Principal Investigator: Leung, Dr A
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Highways England Network Rail
Department: Civil Engineering
Organisation: University of Dundee
Scheme: First Grant - Revised 2009
Starts: 07 November 2016 Ends: 06 May 2018 Value (£): 99,642
EPSRC Research Topic Classifications:
Ground Engineering
EPSRC Industrial Sector Classifications:
Construction
Related Grants:
Panel History:
Panel DatePanel NameOutcome
13 Apr 2016 Engineering Prioritisation Panel Meeting 13 April 2016 Announced
Summary on Grant Application Form
Under the effect of climate change, increasingly intense rainfall has caused frequent failures of UK transport infrastructure slopes/embankments. These failures have severely disrupted the serviceability of the transport network (which are vital in supporting national economic growth) and consequently led to significant socio-economic losses. There have been challenges for the engineers, planners and stakeholders to devise environmentally-friendly stabilisation techniques to withstand the negative impact of irreversible environmental change, while at the same time protecting the natural environment/ecosystems, which underpin the economic prosperity, health and wellbeing of society. Various slope stabilisation methods have been developed, such as sprayed concrete cover and piling. However, these traditional "hard" engineering methods have high embodied CO2, resulting in greenhouse gas emissions that have been linked to further increased climate change. This emphasises the urgency to develop a low-carbon and more sustainable engineering solution that can increase resilience and protect vital transport embankments.

The slope bioengineering method (SBM) using stem cuttings (known as live poles) is an aesthetically-pleasing, environmentally- and ecologically-friendly alternative to the traditional "hard" engineering methods, as this technique provides additional environmental and societal benefits of carbon fixation, enhanced biodiversity and ecosystem restoration within the built environment. Plant roots provide direct mechanical stabilisation to embankments and also act as a "bio-pump" during transpiration to remove soil moisture, which in turn increases soil strength and, hence, embankment stability. However, seasonal variation of soil suction due to plant transpiration potentially results in ground surface settlement/heave, which disrupts the serviceability of embankments (e.g. train speed restriction and delay, poor railway track quality and maintenance). Such disruption is more prominent when embankments are made of clay material that is vulnerable to shrinkage/swelling upon soil moisture changes. An interesting question hence arises: Is SBM suitable to be applied to clay fill embankments, and is it capable of maintaining slope stability and preventing from excessive slope deformation simultaneously?

The project will evaluate critically the effectiveness of SBM to combat the influence of different climate-change scenarios on the performance of clay fill embankments. The work described in this proposal represents the first systematic physical model tests for small-scale model embankments (made of real soil) supported by novel water-uptake pole models within a geotechnical centrifuge. The pole models will be designed to have similar strength and stiffness to real poles, and will also be capable of simulating the effects of plant root-water uptake in the soil. Highly-instrumented centrifuge tests are designed to investigate holistically whether the change of the soil water regime due to root-water uptake in a bioengineered embankment magnifies the clay shrink-swell response, which in turn leads to seasonally-driven failure and ground surface settlement/heave. Different vegetation management schemes (through selection of plant types and arrangements) will also be examined to optimise the performance of embankments for minimising ground surface settlement, while enhancing embankment stability. The project will provide a unique test database that contains new knowledge for end users to develop increased confidence for wider deploying SBM in practice.

The new knowledge and insight derived from this project will not be limited only to transport infrastructure slopes/embankments, but extends also to wider engineering applications. These include enhancing the performance of earthworks for flood defence and landfill covers, which are critical elements of civil infrastructure that are vulnerable to the effects of climate change.
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Organisation Website: http://www.dundee.ac.uk