EVO keeps tunnel machine on straight and narrow
The largest tunnel-boring machine ever deployed in the Southern Hemisphere is using advanced Enerpac synchronous hydraulic technology to tilt, push and turn the 3600-tonne machine.
The 100-metre long monster – aptly named Alice – is using its 14.5m diameter cutting head to chew through more than 800,000 cubic metres of subsurface rock as part of the Waterview Connection motorway project in Auckland.
Descending as much as 45m, Alice is boring Australasia’s largest-ever tunnel as a centrepiece of one of the most important infrastructure developments ever to take place in the country.
The $1.4bn project will complete a motorway ring route around the city by 2017, creating a direct link between the airport and Auckland’s CBD – reducing travel times between the two points by around 15 minutes.
The New Zealand Transport Agency has appointed a team that includes the Enerpac organisation, and Enerpac’s Australasian partners, Smith Cranes and sister company Universal Cranes.
Enerpac and partners are giving Alice a powerful but delicate hydraulic helping hand in her work, using a new generation Enerpac EVO synchronous lifting system that replaces manual control of hydraulic heavy lifting with PLC control of multiple cylinder lifts.
With synchronous lifting, one operator controls the entire precision lowering, positioning and pushing process, during which the status of every cylinder is constantly monitored and displayed at a central control point.
EVO technology involves a 12-point system on the Waterview Connection project, controlling 10 cylinders weighing 600 tonnes with internal stroke sensors.
When Alice completes one length of tunnel, the synchronous system is redeployed to tilt and turn her around to complete the other parallel length of the dual carriageway.
“By using digitally controlled hydraulics to accurately and safely lift, shift and balance some of the largest and most challenging structures on earth, the EVO system offers accuracy, safety and productivity benefits for precision lifting of heavy infrastructure and resources industry machinery,” says Richard Verhoeff, Australasian integrated solutions manager for Enerpac.
The firm’s synchronous system has been widely employed in the Asia-Pacific for tasks as diverse as splitting mining draglines and hoisting ball mills and generators, through to launching marine structures, including a 50,000 tonne floating oil production platform in Malaysia.
“In addition to precision and safety, time saving is a major advantage of synchronous lifting,” says Verhoeff. “The process does not have to be stopped after any incremental value, checked, manually remeasured and corrected.
“The EVO system carries out these actions during the entire lifting process, even with low lifting or lowering speeds. Depending on the application, time savings up to 60 per cent can be achieved.”
The versatility of Enerpac’s family of synchronous systems is further illustrated by the fact that a crane-borne version of the technology, called SyncHoist, was used earlier to position the tunnel boring machine (TBM) parts while the custom-designed machine was being assembled. The TBM was built by
the German company Herrenknecht in China.
A crane-borne Enerpac SynchHoist system handling control tower sections of one of the 28,000 tonne landing helicopter deck vessels being built by BAE Systems Australia
Alice is the 10th largest boring machine in the world and has a top speed of 80mm a minute or 0.005 km/h. This will allow it to cover the total 4.8km journey to Waterview and back in two years.
The primary advantage of an EPBM is that it maintains the pressure in the shield’s cutting head to that of the soil around it, thereby stopping the ground above from subsiding as the machine drills through it.
Enerpac’s EVO synchronous system offers eight standard hydraulic control modes and can control four, eight or 12 points with one hydraulic power unit (HPU). A master control unit is also available that offers daisy chain control of up to 16 EVO systems, giving a maximum of 192 lifting points.
The firm’s synchronous systems is employed globally for safe and efficient lifting, launching, positioning, hoisting, jacking, weighing, load monitoring, determining centre of gravity, tilting levelling, skidding sliding, tensioning and pre-stressing, synchronous displacement, data recording, testing, depropping, load transfer and pressing.
Applications include permanent hydraulic installations, oil, gas and petrochemical, power generation, wind power, mining, shipbuilding, marine, production, manufacturing, load transportation, aerospace and transport including railroad.
The tunnel boring machine in Auckland is controlled using the Enerpac EVO synchronous lifting system. Photo supplied