Robust Rock Machine is a Workhorse of the TBM World

Robbins Main Beam ramps up at Mid-Halton Outfall Tunnel

On July 22, 2015, a 3.5 m (11.5 ft) Robbins Main Beam TBM began a new chapter in its storied 32-year career. Originally built for the Terror Lake project in Alaska, the veteran machine has been used all over the world, most recently in Hong Kong.  Including its new 6.3 km (4.0 mi) long tunnel for the Mid-Halton Outfall in Ontario, Canada, the machine will have bored nearly 30 km (18.6 mi) of tunnels since 1983.

Officials from the Mid-Halton Region visit the hard-working Robbins Main Beam, nicknamed “Peggie” in the Solon, Ohio, USA manufacturing facility. Photo Credit: Michelle Hill, NASTT. 

The machine’s latest endeavor will not be without challenges.  The rebuilt TBM has been beefed up for high-capacity tunneling in hard rock. Geology is expected to consist of laminated shale with interbedded limestone and siltstone layers and a maximum rock strength of 120 MPa UCS.  “We have kept this a simple, streamlined Main Beam machine, but we modified the cutterhead with larger muck buckets, so material can be moved through it faster,” explained Robbins Project Manager Lynne Stanziale.  In addition the TBM was outfitted with fully modernized VFDs, electronics, and high-capacity gearing and motors. The back-up system was also modified to make it more mobile through two 130 m (427 ft) radius curves that the TBM will have to navigate, one in each direction.

“The concept of using refurbished TBMs bears great opportunities for value-for-money constructors,” said Christian Zoller, Commercial Project Manager for contractor STRABAG.  “Our TBM ‘Peggie’ is evidence of that--when well-maintained and professionally refurbished, the lifespan of these machines is extensive. We’re pleased to see that our client Halton Region has the forward-oriented mindset that allows STRABAG to provide its renowned high level of skill and quality, paired with the good value for money that a refurbished TBM yields.”  

Contractor STRABAG, who has had several projects in Canada including the epic Niagara Tunnel project, is in charge of the works.  In addition to the tunnel, STRABAG had to construct two deep shafts for the launch and exit of the TBM.   The scheme involves two sections of tunnel designed to carry treated effluent water from a treatment plant in Oakville into Lake Ontario.  The completed system will upgrade water treatment capacity in the Halton Region of Ontario.

The Robbins Main Beam TBM has been in service since 1983, and with its new project for the Mid-Halton Outfall, it will have bored nearly 30 km (18.6 mi) of tunnels.

The TBM was launched from a 12 m (39 ft) diameter, 62 m (203 ft) deep shaft and is ramping up production, having excavated over 300 m by early September 2015.  “An ongoing challenge associated with the tunneling on this project is the requirement to drive the TBM downhill for the first 4 km (2.5 mi) of the tunnel. Keeping the water that infiltrates the tunnel from flowing directly to the cutterhead requires significant effort,” said Terry McNulty, Technical Project Manager for STRABAG.

 Management of water inflows is not the only challenge. A portion of the drive will curve to run directly under Lake Ontario for 2.1 km (1.3 mi), though the tunnel is deep enough that it will remain in bedrock. Once the machine has completed its final bore under Lake Ontario, it will be backed out of the blind heading and removed from an 8.0 m (26 ft) diameter shaft in a local park.  

Contractor Strabag lowers the main beam of the Robbins TBM into the 62 m (203 ft) deep launch shaft.

“We can already see the potential performance that this TBM will have, once fully assembled and tested. We look forward to the continued support and cooperation with our partner Robbins on this endeavor,” said Zoller.  Though the TBM has only recently started up, crews are moving forward with a plan to line the tunnel with mesh panels and ring beams if necessary.  A cast-in-place liner will follow on after tunneling is completed in August 2017. 

Breakthrough Robbins Machine Breaks Through

“Crossover” TBM Completes Mine Tunnels

                                       A ground-breaking TBM brought a mining operation one step closer to first coal on February 9, 2015.  The Robbins Dual Mode “Crossover” Rock/EPB TBM completed tunneling at Anglo American’s Grosvenor Project in Queensland, Australia. The “Crossover” designation is new for Robbins Dual Mode TBMs, and will be used for all such projects going forward.  The efficient type of TBM used at Grosvenor is now known as an XRE, standing for Crossover between Rock/EPB. Other types of machines are designated the XSE (Crossover between Slurry/EPB) and the XRS (Crossover between Rock/Slurry).

The Grosvenor Mine, a Greenfield coal operation, was the first to utilize TBM technology for mining tunnels in Queensland.  Mine owner Anglo American Coal chose the 8.0 m (26.2 ft) machine for two decline access tunnels at grades of 1:6 and 1:8, one for conveyors and another for people and equipment.

 

The Robbins Crossover Rock/EPB was launched in December 2013 following Onsite First Time Assembly (OFTA) at the jobsite

The XRE TBM was picked over the traditionally-used roadheader method for several reasons, including excavation speed and tunnel maintenance. The choice proved prescient with the machine excavating at a rate approximately ten to fourteen times faster than a roadheader—about 70 m per week for the TBM vs. 5 m per week for a roadheader. In addition, the final tunnels have a smooth profile and are segment-lined, requiring minimal upkeep during the planned 40-year life of the mine. “In the coal mining community, and certainly in Queensland, companies are aware of the Grosvenor project and how it has set a benchmark for underground access drift construction,” said Glen Maynard, Robbins Field Service Site Supervisor at Grosvenor.

 

Rates of tunneling for the Robbins Crossover TBM were fourteen times faster than that of a traditional roadheader excavation Image: Courtesy of Anglo American

The machine’s Crossover capabilities enabled it to operate in both hard rock and mixed ground. In addition, the TBM was required to operate during gaseous conditions.  The unique TBM design included a cutterhead capable of interchanging hard rock and soft ground cutting tools, a two-stage center-mounted screw conveyor, a “quick removal” shield system, and flame-proof machine components due to the possibility of methane gas in the underground environment.

The TBM was optimized for hard rock and mixed ground excavation in geology ranging from soft clay and soil to sandstone and basalt. The two-stage screw conveyor worked in both ground conditions to draw muck from the tunnel face. Two sets of shields were built for the TBM’s “Quick Removal” system, and were detached from the machine at the end of each blind tunnel to be left in the ground for constant support, a requirement in Australian tunnels. The inner core components of the TBM were then retracted out of the segment-lined tunnels on specially designed transport dollies.

The machine began boring the conveyor tunnel in December 2013, and after completion in May 2014 was successfully retracted and transported to the second tunnel site. The machine was then re-commissioned for the people and equipment tunnel in November 2014 with a new set of shields. Once excavation commenced, boring was completed in 88 days at an average of 10.9 m per day, with a best day of 25.2 m. The bore itself was similar to the first, with few challenges encountered other than elevated methane gas levels that required several temporary stoppages in order to safely remove the gas from the tunnel. “The machine performed very well and had high reliability. The cutting tools, in particular the knife edge bits, were exceptional. The bits were required for most of the drive and one complete set lasted 650 meters,” said Maynard.

 

The Robbins Crossover Rock/EPB machine completes tunneling on February 9, 2015. Image: Courtesy of Anglo American

The team is now preparing the machine for its final retraction and roll-out, and it will be on the surface in less than two months.  The TBM will then be stored onsite for future Anglo American mining projects.

 

Workers from owner Anglo American celebrate the breakthrough of the Robbins Crossover Rock/EPB machine on February 9, 2015. Image: Courtesy of Anglo American

Once the longwall mine is operational in 2016, Grosvenor is expected to produce five million tonnes of coal per year over the next 26 years.

Announcing the Crossover Series of Robbins TBMs

Dual Mode Machines bridge the gap in Mixed Ground

                                                                 

The Robbins Crossover Series of TBMs includes the XRE (Rock/EPB) machine, a TBM type that recently completed swift tunneling at Australia’s Grosvenor Decline project.

                                         

Robbins proudly announces its Crossover Series of TBMs, a line of field-tested, rugged Dual Mode-type machines.  Crossover TBMs feature aspects of two TBM types, and are ideal for mixed ground conditions that might otherwise require multiple tunneling machines.  The XRE (standing for Crossover Rock /EPB) is the most common type of hybrid machine, and features characteristics of Single Shield Hard Rock machines and EPBs for efficient excavation in mixed soils with rock.  An XRE TBM recently completed tunneling at Australia’s Grosvenor Decline Tunnel, where it excavated two mine access drives at rates fourteen times faster than a traditional roadheader.  The latest drive was completed on February 9, 2015. “This was a big step forward for the mine to appropriately use civil tunneling technology for a mining application. I take my hat off to the management of owner Anglo American Coal to have the foresight and leadership ability to take this step. Using the Crossover technology [versus the traditionally-used roadheader method], the project was finished on schedule,” said Lok Home, Robbins President.

Additional types of Crossover machines include the XSE (Crossover between Slurry/EPB) and the XRS (Crossover between Rock/Slurry) TBMs.  The Crossover series is quickly gaining in popularity, with Robbins Crossover TBMs currently being assembled in Mexico, Turkey, and Azerbaijan.  An XRE TBM will begin excavation for Mexico’s Túnel Emisor Poniente II (TEP II) later this year, while an XSE is being readied for excavation at the Baku Metro.

 

The Robbins Crossover (XRE) TBM pictured here is at the forefront of a trend for efficient machines that can operate in mixed ground conditions.

The rebranding and Crossover terminology embodies the concept that the machines are able to cross over between modes, says Home. The unique machines are a top focus point for the company: “Robbins comes at this business with extensive rock experience so everything we design comes with the assumption that there will be tough conditions. When you have to “cross over” to another mode then already you are in difficult conditions, and contractors need robust machines to get through these challenges,” says Home. 

Home foresees that machine sales will grow as more projects worldwide are planned in difficult and varying ground conditions. Survey results back up the trend, indicating an increased interest in Crossover-type machines worldwide. “This is a continuous evolution and we are consistently endeavoring to improve Crossover designs. We have three of the machines in production now and I see this number increasing year by year as the industry sees and accepts their value.”