Sydney Metro,
Australia

IGT undertook design of the excavation and support measures and secondary lining of a crossover cavern. The structure is located in sandstone and was constructed from around the centre of the cavern outwards using a temporary crosscut located in the Luna Park Fault Zone.

Outside the fault, the support was provided almost exclusively by rock bolts. A steel fibre reinforced concrete primary lining was also in the fault zone.

The secondary lining was constructed in-situ, partly with conventional reinforced and partly with steel fibres. The design included a headwall and interfaces with the adjoining Barangaroo Station and details to aid the launch of two TBMs from the cavern for the drive under Sydney Harbour.

Crossrail, London, United Kingdom
Lots C300, C410 & C435

With a length of around 120 km, Crossrail will link the eastern and western extents of Greater London. The heart of the new railway project is the tunnelled section. Twin-bore tunnels with a length of 21 km cross the centre of London.

Between the portals at Royal Oak, Pudding Mill Lane and Plumstead, new underground stations and connections to the existing London Underground were constructed at Bond Street, Tottenham Court Road, Farringdon, Liverpool Street and Whitechapel.

The running tunnels were constructed by earth-pressure-balance machines (EPB-TBM). The platform tunnels, access passageways, cross passages, etc. are mined tunnels with steel fibre reinforced linings.

As part of this extensive and complex project, IGT provided the following services:

• Design checks (category 3 checks) for the temporary and permanent works for the station tunnels, including check analysis and design of the temporary support measures for tunnel excavation works.
• Technical site supervision, including preparation of excavation and support requirements and interpretation of underground monitoring data for the contractor Team BFK at Bond Street, Tottenham Court Road and the Fisher Street Crossover.

Istanbul Strait Road Tube Crossing
Bosporus Tunnel, Turkey

Istanbul is a metropolis of several million inhabitants, where space is at a premium. the Eurasia Tunnel links the Asian and European sides of Istanbul with a double-decker tunnel under the Bosporus. The project aimed to relieve traffic in the city. The tunnel results in avoidance of traffic jams and reduces commute times between the two parts of the city to less than 15 minutes.
The tunnel is situation 106 m under the sea and has capacity for approximately 60,000 vehicles.

IGT designed the NATM sections on the Asian side and the box excavation immediately adjacent to the sea (Asian Transition Box – ATB), which served as the launch box for the TBM tunnels, and the start point for the NATM drive and presented a particular challenge.

The 170m-long, up to 36m-wide, max. 40m-deep ATB was excavated through man-made deposits and decomposed rock before reaching the more competent sedimentary Trakya Formation at lower depths. The top section of the box was constructed within a watertight secant pile wall, the lower section with a discontinuous pile wall, each retained with strand anchors. Following the TBM drive, the box was used as the transition structure from the NATM tunnelst o the double-decker TBM tunnel.