By rosebell
Due to exictence of the extremely hard and abrasive rock that wore down cutter discs on the edge of the cutterhead very quickly as it traversed a curve in the tunnel, the Snowy 2.0 TBM that was digging the headrace tunnel on the Australian pumped hydro project was halted in May and currently it has made some small progress.
In order to removing rock pinching on TBM Florence’s shield, specialist contractors have been carrying out hydro blasting work.
According to Snowy Hydro’s latest project update: “In recent weeks we have moved TBM Florence forward in small increments several times and the machine remains fully operational.”
Considering that the surrounding rock disintegrates due to the high-pressure hydro blasting, TBM Florence can navigate the curve onto the straight headrace tunnel alignment.
At the Tantangara Reservoir, the gate shaft has been excavated and work is now focused on the two transition tunnels either side.
In accordance with schedule for completion in July, these tunnels are well advanced, with the full length of the top heading complete and excavation to the invert.
While the intake is now around 45m deep, the remaining excavation is being co-ordinated with work on the third transition tunnel.
For letting water to flow through the intake and into the headrace tunnel, removal of the temporary rock plug and digging into Tantangara Reservoir will be the next stage of the intake earthworks.
Including the intake diffuser, tunnel transitions as well as headrace tunnel, the gate shaft is one of the key structures in the overall Tantangara intake system.
The main function of the gate shaft is to stop and start the flow of water into the headrace tunnel and power station for maintenance purposes or in the case of an emergency.
