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BGS shortlisted for Ground Engineering awards

The British Geological Survey (BGS) has been shortlisted for an award for its high-resolution geological characterisation of the Lower Thames Crossing.

04/11/2020 By BGS Press

The Ground Engineering Awards are hailed as some of the most prestigious awards in the geotechnical industry, celebrating outstanding projects, people and business achievements over the last 12 months.

BGS is among eleven UK businesses and organisations to be shortlisted in the category for Technical Excellence, with the winners set to be announced at a virtual ceremony on Wednesday 4 November.

The Lower Thames Crossing (or Third Thames Crossing) is a major infrastructure project involving a proposed new road crossing of the River Thames estuary linking the county of Kent with the county of Essex through Thurrock.

Part of the biggest investment in the country’s road network for a generation, according to Highways England, it is proposed to include the longest road tunnel in the UK, stretching 2.6 miles, in addition to 14.3 miles of new road, and around 50 new bridges and viaducts offering better journeys and fewer delays.

BGS has undertaken work to help accurately identify and predict ground conditions, which is essential for optimising the design of the scheme.

BGS is being recognised for technical excellence due to its use of innovative methods to characterise the spatial distribution and size of flints that will help to inform the design of tunnelling equipment, and its use of passive seismic data to produce a 3D ground model.

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Having an accurate model of the Superficial and Bedrock deposits reduces the potential risk of unforeseen ground conditions for the tunnel and the associated infrastructure including the motorway network.

Identifying the precise stratigraphical level of the Superficial and Bedrock deposits that the proposed tunnel intersects, was critical to quantifying the potential amount of flint present and their impact on tunnelling equipment.

Understanding the proportion of flints, their size, geometry and distribution will help inform the design of the tunnel boring machines and the chalk slurry treatment plants which this will impact on, as any delays in tunnelling will cost money.

Ricky Terrington, BGS 3D Geospatial Lead

The work, carried out on behalf of the Lower Thames Crossing-CASCADE Consortium, draws on a range of expertise at BGS, including field geologists, palaeontologists, geophysicists and laser scanning technicians.

BGS used in-situ field measurements of flints, coupled with data from high resolution optical intensity laser scans from old chalk pits and sections, to measure the size and distribution of individual flints and bands.

This data is tied to a high resolution Chalk stratigraphy so that predictions of flint size and distribution in the proposed tunnel route can be estimated.

Novel passive seismic geophysical surveys were used to identify rock-head and the base-Palaeogene surface across the route corridor, calibrated using borehole logs.

The small, portable nature of the equipment and rapid data acquisition enabled BGS to survey rapidly and reliably, including areas where traditional invasive SI methods were not possible.

This is both quicker and cheaper than using traditional ground investigation methods, giving greater confidence to the ground model and reducing risk.

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