As part of the High Speed 2 (HS2) Euston Station enabling works, this project involves the construction of a replacement ventilation/substation shaft and associated tunnels including a temporary construction shaft. The SCL tunnels connecting the new vent shaft with existing LU infrastructure will be formed with two linings, a fibre reinforced sprayed concrete primary lining and a cast‐in‐place concrete secondary lining. The tunnels will be constructed in advance of the main HS2 works and the tunnel vertical alignment allows for future excavation of the station box above the tunnels.
The temporary construction shaft is required to facilitate the construction of the tunnels and consists of 8.2m diameter segmental lining constructed to a depth of 11m, followed by SCL which flares out from the segmental lining to a diameter of 10.25m. The shaft forms a chamber from which the two tunnels are connected.
The ventilation and substation shaft will form a new multi-storey building housing LU equipment spread across five floors. The shaft will be constructed using secant pile walls and a bottom-up construction method with a footprint of 20m (W) x 20m (L) x 20m (D).
Gall Zeidler Consultants has been commissioned to undertake the Category 3 Check of the design of a new London Underground Substation/Vent Shaft, Temporary Construction Shaft and associated Tunnels. The CAT 3 check comprises independent reviews, checks and check calculations of the detailed design (RIBA 4 stage) relating to the tunnel, substation/ventilation shaft and construction shaft and analysis of the structures.
Construction 2020-2021 (planned)
Temporary Construction Shaft (pre-cast concrete segments, SCL), SCL Tunnels, Ventilation Shaft
SCL Tunnels approximately 85m in length.
SCL tunnels approximately 6.5m inexcavated diameter.
London Clay and Lambeth Group
Est. £300 million