TBM Kirsten at Maximum Incline!

TBM Kirsten is now at the maximum gradient as she excavates up the inclined pressure shaft

The 200-metre long TBM Kirsten (TBM 1) has completed 275 metres (of 1225m) and is now at the highest gradient in her journey tunnelling upwards to excavate the inclined pressure shaft (IPS).

Varun Tyagi has been tunnelling for 17 years and is the Deputy TBM Construction Manager. He is proud of the world-leading work and innovative methods used to excavate the inclined pressure shaft. Kirsten will now excavate the straighter part of the incline tunnel.

Varun describes the various challenges and innovations involved with tunnelling the inclined pressure shaft.

“First of all, we are excavating the slope itself, second is the segmental lining, third is the grouting operations, fourth is using MSV’s (multi service vehicles) with the rack and pinion system, and fifth is the monorail on that slope, for transporting people,” Varun said.

The Force Activated Coupling System (FACS) segments have been specially designed to withstand the extreme water pressure when the powerhouse is operating.

Varun says for every two metres Kirsten advances forward, there are changes in conditions.  In relation to safety, working in such a unique environment, Varun says there is a tenfold increase in safety.

“Working onboard a TBM itself is a challenge to maintain pace while monitoring the parameters for the excavation. We are also continuously extending the services at the back of the TBM as it advances as well as extending the rack and pinion system, monorail system, service pipes, and ventilation,” he said.

Overall, Varun feels very proud. “On this large scale, what the team are engineering is groundbreaking, and executing the inclined pressure shaft with TBM Kirsten is a world first,” Varun said.