Design Of Complex Permanent Tunnel Linings At Sydney Metro’s Victoria Cross Station

The permanent tunnel linings of Victoria Cross Station include complex intersections associated with their asymmetric geometry, significant groundwater and rock loads, and the large span of the station cavern.

Victoria Cross is one of six underground railway stations recently completed by the John Holland CPB Ghella JV (JHCPBG JV) as part of the Sydney Metro City & Southwest project. Sydney Metro is Australia’s biggest public transport project, which will deliver 31 metro stations and more than 66km of new metro rail line. It runs from Sydney’s northwest region, beneath Sydney Harbour, through new CBD stations and then southwest to Bankstown.

Victoria Cross Station comprises a 265 metre long cavern with several pedestrian and service adits connecting the cavern to two adjacent shafts. Located beneath Miller Street in North Sydney, it includes the largest cavern on the project with a clear span of 24 metres and internal height of almost 16 metres.

The design of the permanent lining at the intersection between the lift access adit, lift shaft and the cavern was particularly challenging due to the complex geometry. The lift shaft intersects the crown of the cavern and connects to the access adit located above the cavern, with these two structures separated by only a 2 metre thick sandstone slab. A range of numerical modelling techniques were developed to address the various design considerations which applied to this complex intersection.

The design requirement for the station permanent lining to be tanked led to the lining having to accommodate significant groundwater loads in addition to the large rock loads associated with a cavern of this span. Three-dimensional finite element modelling was undertaken to assess the interaction between the cavern and overlying lift adit structures as well as to inform the articulation and waterproofing details at different structural interfaces.