16/11/2023
Completed Project – Westconnex M4-M5 SPI Ventilation Shaft
After the interest in our benching project summary, we thought we would detail another of our past projects.
Lendlease Samsung Bouygues Construction Australia Joint Venture (LSBJV) awarded the St.Peters Interchange MDS-10 Ventilation Shaft construction (SPI Vent shafts) to SU Tunnel and Civil Services and works began in July 2020.
The project involved the construction of two ventilation shafts in a short timeframe. Excavation of 1,585BCM was in hard shale material and the use of innovate plant solutions assisted in the successful delivery of the project. During excavation, 577 rockbolts and 120m3 of shotcrete was used. These plant innovations provided many advantages including safety benefits, reduced man hours on-site, reduction in program duration and greater certainty of cost with SU providing an entire solution and no requirement for contractor interactions.
Located within tunnel cross-passages, shaft access was difficult. The dimensions of the tunnels were 10-13m (L) x 6.5m (W) x 10m (D) which required small equipment be used, small enough to be lifted in/out of the shafts by mobile cranes.
As the excavation got deeper, the ground got harder. With only small excavator use possible to access the shaft, larger machines were required to remove the hard rock efficiently. As a result, options were explored including innovative attachments to assist in the excavation. A 3m extension arm was fabricated to allow the large 24t Excavator to hammer deeper with the 1.5t rock hammer. This assisted in expediating the removal of the hard shale rather than the much smaller breaker affixed to the 8t excavator.
Rather than using a crane and muck bin to muck out material in the lower benches (RL -4 to -10m) a 6m dipper arm extension was fitted to the 24t excavator. This allowed mucking out activities to be faster, with only one operator required (rather than a crane crew).
