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Melbourne Metro

Melbourne Metro: five new underground stations

The Melbourne city’s metropolitan rail service operates 226 six-carriage trains across 998 km of tracks. The Metro has 15 lines and 222 stations, serving more than 400,000 passengers a day across the city.

In 2017, the construction of a 9 km long tunnel and five new underground stations were announced for greater capacity and additional coverage of the suburban area of the city.

The construction started in 2018. Dextra was involved in the project by supplying rebar connectors with fully automated rebar preparation equipment for the stations’ structure reinforcement works.

Griptec couplers were chosen thanks to the unrivaled performance in tension, compression and fatigue, and 400,000 units have been delivered.

Moreover, Dextra also supplied:

  • 5,300 GFRP Astec Combination Bolts. It is used at the CBD cavern location. The 19m width of the cavern allowed for the construction of two conventional 7m tunnels, built in parallel with the middle segments secured by GFRP CB Bolts, that can be cut to make the gallery wider.
  • 2,400 GFRP Geotec GR45 – 25mm dowels of 11.8 meters long were used to secure the face during the excavation.
  • 900 GFRP Astec soil nails ST50 – 41 were applied to secure several stations under construction. Some of them are outside of the boundary of the project since the GFRP can remain on the ground outside of their property and can easily be cut later.
  • 16 soft eyes were used in d-wall and bored pile of five stations.

Dextra was able to support and share their expertise on GFRP at design stage and produce the GFRP shaped solutions as per the owner expectation. Thanks to the cuttability of the GFRP, the TBM can pass through the d-wall in a limited time without any damages.

The Metro tunnel and its new stations are due to open in 2025 and predicted to be a new landmark of the city.

(photo credit: Hugh Llewelyn at https://bit.ly/2S0kbAG)

Hyosung LPG Cavern

Hyosung LPG Cavern

This multi-phase project handled by Hyosung Group will include a propane dehydrogenation (PDH) production plant, a polypropylene (PP) plant, a liquefied petroleum gas (LPG) storage tank, and warehouses for LPG and petrochemical products.

The whole complex will cover 60 hectares of the Cai Mep Industrial Zone in Ba Ria-Vung Tau, located near Ho Chi Minh City.

Dextra is supporting the construction of the 240,000-ton LPG underground storage facility by supplying 30,000 units of glass fiber reinforced polymer (GFRP) rock bolts to consolidate the cavern rock face around the 150m deep excavation area.

Injecting sea water inside the rocks around the cavern will create a water curtain that will effectively prevent any oil leakage: in this high corrosive environment, GFRP is the ideal solution.

Dextra GFRP Rock Bolts are cuttable mining anchors based on fully threaded GFRP tendons. The bolts are available in 7 diameters from 20mm to 40mm, delivered with GFRP plate and nuts. Due to GFRP’s lightweight nature, it is easy to handle, transport and installation inside the tunnel.

The facilities are expected to begin commercial operation in 2020.

Deep Tunnel Sewerage System (DTSS) – Phase 2

Deep Tunnel Sewerage System (DTSS) – Phase 2

The Deep Tunnel Sewerage System (DTSS) is a used water infrastructure project being developed by the Public Utilities Board (PUB) of Singapore to meet the country’s long-term clean water needs.

DTSS deploys deep tunnels to convey used water to 3 centralized water reclamation plants (WRP) located in the coastal areas.

The used water is then treated and further purified into clean water to be supplied under the brand name NEWater, with excess treated effluent discharged to the sea through outfall pipes.

The project involves the construction of two large tunnels, 6.5m in diameter and with a total length of 80km, located about 50m below the surface, to carry sewage to 3 centralized WRPs.

The project is developed in two phases. The first phase was completed in 2008 and comprises a 48-km-long deep tunnel system to channel the flow of water from existing gravity sewers to the Changi WRP in the east and Kranji WRP in the north.

The second phase will extend the tunnel system to the west through a 30-km-long south tunnel, 60km of link sewers, the Tuas WRP and a 12-km deep-sea outfall.

For the second phase, Dextra supplied 1,210 rock bolts for stabilizing the tunnel excavations and 8 GFRP Soft-Eyes for TBM breakthrough.

Soft Eye & Rock Bolt

On completion of phase 2, anticipated to be in 2022, the NEWater factory at the Tuas WRP will contribute to 55% of the total water demand of Singapore.

In addition, the Tuas WRP will treat 800,000 cubic meters of used water per day, making it the largest membrane bioreactor facility in the world.

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