The Thames Tideway Tunnel is London’s new ‘super-sewer’ designed to bolster the already stretched existing sewerage system, by intercepting waste that would otherwise overflow into the Thames. The original London sewers opened by Edward Prince of Wales in 1865, and designed by Joseph Bazalgette, were built in to the Thames flood defence walls and also contain a large service subway. The service subway between Victoria and Blackfriars contains 2no. 36” gas mains.
Key technical challenges
Our approach to this job during the initial due diligence and VE phase resulted in reduction of the core wall and typical slab thicknesses. We also conducted an in-depth study of the dynamic performance of the building and its piled foundation under different load conditions to satisfy both strength and occupant comfort criteria.
The new 7.2m diameter sewer tunnel will be bored using tunnel boring machines which will cause ground movement as they pass. The ground movement analysis has found that whilst these ground movements will be acceptable for most in and on ground structures – including the original brick sewers in the embankment – aging gas main pipes fixed in to the service subway are at risk, and must be diverted.
The key technical challenge is how to divert the gas mains embedded within the existing Thames flood defence walls, without compromising the walls that defend London against the daily tidal rise and fall of the River Thames. Robert Bird Group have solved this problem through a series of carefully sequenced permanent works structures designed to act in the temporary condition, establishing stakeholder support and buy-in on behalf of FLO.
£4.2 billion GBP
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