'Seeing inside flood embankments' - novel geophysical imaging approaches for assessing the health of safety-critical flood defence infrastructure

Lead Research Organisation: University of Bristol
Department Name: Earth Sciences

Abstract

Project description
There are many thousands of kilometres of earth embankments within the UK flood defence and canal networks, much of which is aging and displaying increasing levels of failure in response to extreme weather events. The failure of these embankments can have severe social and economic impacts in terms of disruption, damage to property, and even loss of life. Conventional approaches to managing these structures are heavily reliant on walkover inspections or remotely sensed information. However, they cannot provide subsurface information; instead they only detect failure once it has begun, by which time it is often too late to undertake remedial action.
This project seeks to develop emerging non-invasive geophysical imaging technologies as a means of rapidly assessing the internal condition of safety critical water retaining structures. The advantage of these techniques is that they have the potential to provide detailed volumetric subsurface information related to, for example, lithology, strength, cavitation and moisture content - thereby greatly assisting in the condition assessment of these structures and early warning of failure.

Aims & Objectives
The overarching objective of the project is to develop new integrated geophysical approaches for condition assessment of flood defence earthworks. Specific aims include:
- Developing optimised survey design solutions for both rapid (2D) characterisation and detailed (3D) assessments.
- Joint interpretation of geophysical and environmental data to develop robust ground models.
- Assessment of the sensitivity of new geophysical approaches to a range of embankment internal erosion scenarios validated through synthetic modelling and field trials.
- Knowledge exchange & dissemination activities to inform good-practice in geophysical characterisation amongst stakeholders in the end-user and academic communities.

Methods
Two strongly complementary classes of geophysical techniques will be investigated - geoelectrics and seismics. Geoelectrical measurements are sensitive to compositional variations (particularly clay content) and groundwater saturation/quality changes, whereas seismic measurements can provide information on geomechanical property variations (elastic stiffness and density) of the subsurface.
Survey design solutions, ground model development and sensitivity analyses will be undertaken using a combination of computer based simulations, small-scale laboratory testing (linking electrical, seismic and other physical properties) and field-scale trials. Trial sites will be provided by the Environment Agency. Detailed experimental design and field site selection will be a collaborative process involving the student, supervisors and CASE partners (Environment Agency and RSK)

Publications

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