In what is described as one of the most complex underground junctions ever built, WestConnex is a 33-kilometer (21 mi) predominantly underground motorway tunnel network in Sydney. Its walls are lined with two permanent sprayed layers: one is a fiber reinforced primary support lining, the other is a fiber reinforced concrete smoothing layer. Both are reinforced with Dramix® 4D steel fiber for optimal load-bearing capacity.
Like many road tunnels in Australia, these are designed as a drained, permanent sprayed concrete lining tunnel. This was especially relevant for this project, because of the low cover and its permeable nature and the proximity of the Wolli Creek.
A spray applied waterproofing membrane was added between the layers of concrete. Both the primary support lining and the final lining were reinforced with Dramix® 4D steel fibers assisted to achieve on average flexural performance of greater than 4.0Mpa at fR1. The primary shotcrete lining was on average 110mm and when required in bad ground conditions as was in Wolli Creek a secondary layer was added at an average thickness of 125mm. In addition, Duomix® M12 polypropylene fibers for fire resistance.
By building the interchange mostly underground, the project will deliver new active transport options in Rozelle: up to 10 hectares of new public parkland, new pedestrian and cycling paths and sports fields.
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