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Modified excavators make short work of TUNNELLING
(M5 East)
This article originally appeared in the September 2000 edition of Construction Contractor magazine.
A Sydney specialist TUNNELLING contractor has developed a fleet of customised Komatsu "short-boom" excavators to carve out a niche for itself in most of Australia 's major underground projects.
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| Shantfell's PC228UU-3 zero slew excavator allows the machine to work right up against tunnel walls, while the specially modified short boom allows them to work in very confined spaces |
Shantfell Underground, has worked on a number of high-profile TUNNELLING projects, including Melbourne 's CityLink and in Sydney , the Eastern Distributor, the Northside Storage Tunnel, the M5 East freeway, Cross City Tunnel, Lane Cove Tunnel and the Eastlink Tunnel.
Shantfell has developed a unique short boom arrangement for its excavators, allowing them to work effectively in very confined spaces.
Its fleet includes a wide range of short booms from 3-35 tonne.
Shantfell also has a number of other excavators, along with articulated dump trucks, road sweepers, skidsteers, water carts, dozers, graders and compactors.
In addition to supplying customised TUNNELLING equipment, Shantfell specialises in providing skilled underground labour.
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One of Shantfell's short-boom PC200-6 excavators, fitted with a rock saw, cutting out trenches for stormwater on the M5 East project. |
Shantfell uses its machines for cutting out trenches for stormwater along the base of the tunnels, electrical conduit in the walls, and cutouts for various control and monitoring systems.
These short-boom excavators make this sort of work so much easier - and they are the only ones available in Australia .
With most tunnels being only 8 m wide by 6 m high, conventional standard-boom machines are very difficult to maneuver in the confined space.
In addition, the 22 tonne zero-swing PC228UU-1 can work with its tracks hard up against a tunnel wall, and still swing through a full 360°.
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A great advantage of the short boom concept is that it allows trucks to get past the excavator without having to reposition.
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It can set up on one side of the tunnel, hammering out penetrations on the opposite side - and when an articulated dump truck carrying excavated material comes through, the excavator simply needs to lift its arm and boom, and the truck can drive underneath.
Its ability to work and maneuver in such a confined space saves us a lot of time in not having to keep repositioning or moving the machine.
Shantfell got into short-boom excavators about five years ago, when it was asked to bid on a shaft excavation for Melbourne 's CityLink project.
They had a 10 m shaft to dig for the project, so we went out to Homebush and painted out a 10 m diameter circle on the ground.
We knew we wanted about a 22 tonne machine to carry out the work, but it soon became obvious that a conventional boom machine just wouldn't fit.
The design developed by Shantfell uses a top cylinder that is the same length as for a conventional boom - which makes it a straightforward job to convert the excavators back to a standard configuration.
It also allows us to get more breakout, and we're able to run larger hammers because of the higher lift capacity we get.
Prior to working on the tunnel trenches on the M5 East, Shantfell carried out excavation of a 40 m deep, 10 m diameter ventilator shaft for the project at Turrella.
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| A short-boom PC200-6 working on a shaft excavation for the M5 East. |
Modified Excavators stars in tunnel work
This is an edited version of an article which appeared in the October 1998 edition of The Earthmover & Civil Contractor magazine, detailing Shantfell's work at that time on the Melbourne CityLink project.
The Transfield-Obayashi Joint Venture CityLink project in Melbourne has included some major tunnelling operations underneath parts of Melbourne and the River Yarra.
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Finding the right equipment to carry out elements of this tunnelling work has been a considerable challenge- one that was accepted by Shantfell, with machinery modified to their needs.
CityLink , which has been hailed as Australia 's largest peace-time construction venture since the Snowy Mountains water scheme, included requirements to excavate a ventilation shaft only 9.5 m in diameter-which meant a normal boom would be too large for the limited space.
A Komatsu PC200 was modified to use a shortened boom with hammer attachment, to enable it to dig the ventilation shaft for the tunnel beneath the suburb of Richmond .
It was a challenging project for Shantfell, not only working in a confined space, but also coping with 20 m of running sand and water which had to be kept continually frozen with nitrogen throughout the operation.
Beyond this, there was a further 4 m of rock to break through before the pouring of cement sides to form a coffer dam and finish off the ventilation shaft. Spoil was removed with 15 tonne kibble cable cranes.
The ventilation shaft took three and a half months to complete, after which road headers were used to bore the road tunnel, which will allow three lanes of traffic to flow in either direction.
Shantfell had a fleet of seven excavators continually working on CityLink.
Following the success and added versatility of its first Komatsu excavator with shortened boom, a number have been modified for the same purpose.
An additional feature of the short-boom Komatsu excavators has been their ability to work in one half of the tunnel, allowing access for trucks and other vehicular traffic access on the other side.
This has allowed free and uninterrupted construction of the forward tunnel, ensuring the project has kept on schedule.
As a result of Shantfell's success on the CityLink project and the expertise gained as specialists in tunnel construction, it has now commissioned a number of short booms to all the major tunnel contracts in.
Further information: Shantfell Underground, ph (02) 9748 7700, e-mail shantfell@iprimus.com.au
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