A Thames Tideway team has been named as one of the finalists for this year's Fleming Award.
The award recognises geotechnical engineering teams that have used innovative methods to deliver underground projects. Some of the innovations from this year's finalists have been so novel and valuable that they've been patented.
As well as the Thames Tideway team, a team working on the upgrade of Bank Underground Station in London, and the Woodsmith Mine Shaft team, from the UK's deepest mine, made up the trio of finalists.
Online registrations are still open for the Fleming Award ceremony where judges will decide the winner, and where Rachel Monteith, Director of Buro Happold, will be giving a brief keynote lecture.
More about the finalists
Bank Underground Station team
The Bank Underground Station team worked on tunnelling through under ream piles.
This was particularly challenging because the optimised tunnel alignment passed through a forest of massive concrete under-ream piles supporting an eight-storey, two-basement office building.
An Innovative Contractor Engagement procurement process, in advance of the Transport and Works Act Order, enabled early collaboration with key stakeholders and hence the unlocking of best value.
Secondly, the use of distributed fibre optic sensors (from Cambridge Centre for Smart Infrastructure and Construction) enabled monitoring of behaviour during tunnelling, pile interception, transfer structure installation and post construction.
It's possibly the first time this has ever been done in close proximity to tunnelling. Several other innovative and collaborative methods were also used.
Thames Tideway team
The Thames Tideway project team are working on a 60m-deep, 18m-diameter shaft to connect a 3m-diameter sewer to the tunnel network at Deptford Church Street.
In this project, the core challenge was that a steeply inclined fissure (70º dip) below the intended shaft diaphragm wall toe level.
The design couldn't be amended because of the diaphragm wall design and equipment available.
So a team of experts from five different firms conducted a further investigation to characterise the chalk at the site in three dimensions.
This team then reviewed the data and designed a new approach, including the use of multiple contractors drilling on the same well, extensive use of borehole geophysics, use of computerised pressure grouting, 3D visualisation within review meetings, specialist materials testing of grout to prove its presence and the use of real-time observational method to verify performance versus predicted response.
Throughout, additional parties had to be added to the team as the need arose.
Woodsmith Mine Shaft Team
The Woodsmith Mine Shaft Team work on the UK’s deepest mine, for Sirius Minerals to extract large quantities of Polyhalite for global distribution.
This project resulted in the deepest diaphragm wall shaft ever constructed in Europe, the development of now-patented GFRP spacer system to centralise primary cages within the wall axis, the use of fast swelling polymer for control of slurry loss, the development of various cutter wheel geometries and teeth configurations to cope with sticky mudstone layers, and digitalisation of performance information and analysis.
All of this took place within the North York Moors National Park, where the planning conditions only allowed for the installation of an ‘invisible’ mine site, with a team of up to 200 employees achieving more than 300,000 RIDDOR free working hours.