In July 2002, the Thiess Hochtief Joint Venture (THJV) was awarded the contract to design and construct the Epping to Chatswood Rail Tunnel. The contract is the largest, single publicly funded contract ever awarded by the NSW Government.
The works comprise of almost 13km of twin tunnels, excavation and construction of the station caverns at Macquarie University, Macquarie Park, and Delhi Road, an underground extension to the existing Epping Station, and installation of the rail tracks and systems. The rail line will link the Main North Line near Epping to the North Shore Line near Chatswood.
The tunnels were excavated using two tunnel boring machines (TBMs) each of which was 210m long and weighing 700 tonnes. The TBM's removed the majority of the 1.7million cubic metres of material required to excavate the tunnels.
Where the TBMs were cutting through unstable strata a combination of reinforcing mesh and steel fibre reinforced shotcrete was applied to the crown from a platform at the head of the TBM in order to stabilise & make safe. As the TBM progressed, precast segments, supplied by Rescrete Industries, were placed approximately 5.5m apart on the tunnel 'floor', then fresh 40 MPa concrete was placed by kibble & monorail between these segments to form a continuous invert.
Circular forms required for Lining the tunnels were fabricated in Austria by Oestu-Stettin, shipped to Australia in containers and assembled on site by THJV. These six forms, travelling on temporary rails, were used to place approximately 105,000 m 3 of 32 MPa concrete lining.
Track Slab installation involves two construction methods: FST (Floating Slab Track) and DFF (Direct Fixation Fastener). The FST placements are slab-jacked and placed on bearings to create a floating slab, which reduces noise & vibration. The DFF is also known as 'Top-Down' construction where the rail line is suspended on spindles & concrete brought up to the baseplates. The DFF construction and rail line installation is being done by an alliance between THJV and Queensland Rail.
The special grades of concrete required over the continuous 24-hour per day construction program for Tunnel invert, Lining & Track Slab were produced from an onsite batch plant operated by THJV. The plant was supplied by Sunstate Engineering, Queensland, with a 2.5 m 3 capacity planetary action wet-mixer from Hallweld Bennett, Adelaide. Much of the 32 & 40 MPa concretes (with W/C ratios as low as 0.38) were produced at 230 mm slump and long slump retention to ensure satisfactory placing & compaction after pumping through 200-240 m of pump line. Concrete was transported to pumps using both Jacon low-profile tunnel & standard road agi trucks.
Blue Circle Southern Cement (BCSC) are the contracted suppliers of bulk cement and flyash to the project on behalf of the THJV, involving 50,000 tonnes of Shrinkage Limited Cement and 20,000 tonnes of Flyash. BCSC have also supplied a 150 tonne mobile storage silo to act as surge capacity for the supply of Shrinkage Limited Cement to cover the round-the-clock operation, since cement deliveries are restricted to 7.00 am until 5.00 pm to comply with EPA noise limitations. Supply to this project commenced in September 2003 and is due to cease in October 2006.
BCSC are well positioned to supply major infrastructure projects such the Epping to Chatswood Rail Tunnel. Our main works, where Shrinkage Limited Cement is manufactured, is located at Berrima, in the Southern Highlands. In addition to this we have other works at Maldon near Picton, Kooragang works near Newcastle, and depots throughout NSW and Vic, including a major depot at Clyde in Sydney.
BCSC have one of the largest fleets of cement tankers in Australia which reinforces our ability to supply major projects in addition to our ongoing customers.
