Sydney Metro Pitt Street station project on track with the AT – Pipe Umbrella System
Pitt Street Station is one of six new stations on the Sydney Metro line in the Sydney CBD. It is 17 meters (north end) to 20 meters (south end) below ground level and extends the subway network from Chatswood under Sydney Harbour to Bankstown. Strategically, the station is located within the southern Sydney CBD and Chinatown.
In late 2020, the tunnel and station excavation contractor completed tunnel and excavation works at Pitt Street Station. Construction of the station and superstructure are now underway and is expected to open in 2024.
The application of the AT – Pipe Umbrella System with squeezed connection provided by DSI Underground has helped to overcome challenging site and ground conditions during the Pitt Street Station development for Sydney Metro.
During the construction of a connection tunnel in the station area, a pipe umbrella was installed underneath a busy road. The ground consisted of mixed loam for approximately two-thirds of the tunnel, with the remaining third of weathered sandstone. Unusually, each pipe umbrella pipe also had to be installed 19 degrees downwards. As a result of mixed ground conditions and angle of installation, a high-quality drilling system such as the AT – Starter Unit with an arc-shaped button drill bit was required.
DSI Underground, the leading global supplier of ground control solutions for Tunneling, worked in cooperation with the drilling equipment specialist Robodrill to install the AT – Pipe Umbrella System consisting of 60 individual pipes with a length of 18 meters each.
The AT – Pipe Umbrella System from DSI Underground is a pre-support measure used to increase the stability of excavations in weak ground. It increases the stability in the working area by transferring loads in the longitudinal direction and decreasing excavation induced deformations.
For this project, DSI Underground’s proprietary squeezed connection for pipe umbrella pipes has been used as a replacement for a conventional threaded connection. The proprietary squeezed connection technology features four main advantages:
- Enhanced working safety
- Proven cycle time savings
- Improved load-bearing capacity
- Optimized quality and utilization rate
By using this type of connection, the time required to install the pipe umbrella at Pitt Street Station has been dramatically reduced, the site construction team was impressed by simple and easy handling.
During the project, DSI Underground provided on-site technical support at Pitt Street site for the first week of the project, while Robodrill staff oversaw installation for the remainder of the project.