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Metro Tunnel

Construction of the station box in Domain

We have made temporary changes to St Kilda Road to allow the new Anzac Station to be built beneath it.

Preparing for station box excavation

In order to excavate the station box, diaphragm walls (D-walls) and concrete piles must first be installed in the ground to support the excavation. Works in May will primarily focus on the northern section of Anzac Station, and move to the southern section later this year.

From early to mid-May 2018 large cranes will arrive to construct D-walls and piles.

A temporary bentonite plant will be installed in May 2018 in Domain. Bentonite clay from this plant will aid in constructing the D-wall, forming the permanent perimeter of the underground station box.

Domain work sites in May 2018

Piling platform

This process starts by testing the redundant St Kilda Road & tram tracks to determine their suitability as a piling platform. The median lanes will then be strengthened to enable cranes and other heavy construction equipment to safely drive and operate across the site during construction

This is done by:

  • Removing redundant services.
  • Removing soil and material.
  • Delivering, spreading and compacting new ground materials.
  • Pouring a concrete slab at ground level.

Piling platform construction will commence in May and is expected to be completed by the end of May 2018. This work will involve up to 10 trucks per day accessing the site via St Kilda Road.

Guide wall construction

Guide walls are constructed in the ground, typically as temporary, lightly reinforced concrete elements that are placed alongside the diaphragm walls. They are important as it helps guide the D-wall equipment vertically and aid in the positioning of the final structure of the station box.

Generally, dimensions of the guide walls are 25 metres deep and 1 metre thick on both sides of the future D-wall structure.

Works include:

  • Demolishing the existing pavement structure along the perimeter of the box.
  • Excavation of a two-metre trench.
  • Concreting the guide wall on site.
  • Up to 20 trucks per day accessing the site via St Kilda Road.

This work will commence in mid-May and will continue until the end of June.

D-wall construction

D-walls are 100cm thick concrete slabs that are installed to a depth of 35 metres along the sides of the station box.

These are constructed by:

  • A trench cutter excavating a hole the size of the D-wall panel.
  • Inserting bentonite into the cutting to support the excavation.
  • Using a crane to lower reinforcement cages into the excavation.
  • Pumping concrete into the bottom of the excavation to create the D-wall, while simultaneously pumping the bentonite back into the bentonite plant where it can be recycled for future use.
  • Joining each panel together to create strong walls along each side of the station box.

This work will occur during the day and will commence at the end of May 2018.