Author: Robbins

TBM Design for Long Distance Tunnels: How to keep Hard Rock TBMs boring for 15 km or more

Today’s Tunnel Boring Machines are often required to bore longer tunnels in harder rock at a faster pace—a trio of challenges that can be daunting for any contractor. With proper design, operation, and maintenance, however, modern TBMs are very capable of reaching their 10,000-hour design life or more. TBMs in the industry today have already accomplished the feats of boring upwards of 50 km on multiple tunnels over decades, and of completing single TBM drives totaling 27 km. With new capabilities, even greater feats may be possible.

From abrasive rock to fault zones to water inflows, geologic challenges become more common as tunnel lengths increase. In rock tunnels over 15 km long, a host of challenges may meet a TBM, requiring a versatile design. General wear and tear is an issue on machines boring long stretches of tunnel, and thus minimization of downtime is key. In order to counteract these challenges, a number of design features can be added during the manufacturing process, and these, combined with regular maintenance and well-designed logistics during tunneling, can result in TBMs lasting for the tunnel length and possibly over multiple projects.

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Optimizing Soft Ground Excavation: Development and Design of EPB and Slurry Cutterheads

The history and development of soft ground tunnelling machines is a long one, and one in which the quest for optimal design to achieve safe and efficient excavation has always been a top priority. Modern soft ground tunnelling began with the introduction of Slurry TBM technology in 1967 and the development of Earth Pressure Balance (EPB) machines a bit later in 1974 in Japan. Many advances have since been made by Japanese manufacturers, as well as North American and European manufacturers. These advances were the result of lessons learned from the successes and failures of the technologies in a variety of geologies. In many cases the philosophies of Japanese and European manufacturers were quite different, resulting in unique machine features. In the case of both EPB and Slurry, many of these advances have involved the development of the cutterhead, which is the first part of the machine to come in contact with the soil. Cutterhead design is not only integral to operation of the TBM, but also to machine performance. Proper cutterhead design must incorporate a variety of project variables including expected geology and operation of the machine. To appropriately specify and evaluate soft ground cutterhead features, there must be an appreciation of how these features developed and how this applies to a job-specific geology.

This paper will review the fundamentals of cutterhead design and how particular attributes interact with the geology and other machine features to achieve efficient excavation. When possible, comparisons between EPB and Slurry technology will be addressed. Comparisons will also be made between the varying schools of thought in terms of soft ground machine design in both Europe and Japan. In addition, the features will be evaluated for potential outcomes with differing geologies and methods of operation. A thorough understanding of these items allows for an educated approach to maximization of machine advance and performance.

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Unique Hybrid EPB Design for use in Coal Mine Drifts

The Grosvenor Decline Tunnel is an ASD $1.95 billion Greenfield metallurgical coal project owned by Anglo American in Moranbah, Central Queensland, approximately 180 kilometers southwest of the coastal port city of Mackay and about 1000 kilometers north of Brisbane. Located just south of the Moranbah North coal mine, it targets the same Gonyella Middle coal seam as the Moranbah mine, and it is expected to produce five million tonnes of coal per annum from its underground long wall operation over the next 26 years.

The Grosvenor Coal Mine has a planned expansion in which two decline tunnels will be required for mine access to the coal seam at the shallowest depth of 130 meters. Longwall panels are planned to be 300 meters in width with lengths up to 6200 meters. The first decline tunnel (Conveyor Drift) will transport the coal from the long wall to the stockpiles area on the surface; the second decline tunnel (Transport Drift) is designed for people and equipment to access the underground once the mine is operational.

For the first time in the Queensland coal industry, a TBM methodology has been developed to ex-cavate both drifts and contribute to construction of the “world-class long wall mine” envisioned by Anglo American. Stability, safety, quality and schedule have been the key factors in the selection of this technology.

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Rescue and Refurbishment of a TBM inundated with Flood Waters at the New York City Harbor Siphon Project

In October 2012, New York City’s Harbor Siphons Project and its 3.6 m CAT EPB ground to a halt when hit by Superstorm Sandy. Despite contractor Tully/OHL JV’s best efforts to mitigate anticipated flood risks, the launch shaft was inundated with seawater, flooding the tunnel and TBM just 460 m into the 2.9 km long drive. A team of Robbins and OHL personnel were able to document, reverse engineer, and refurbish severely corroded components of the TBM while in the tunnel, resulting in a successful re-launch in April 2014. This paper will document the incredible efforts of the team to rescue and refurbish the TBM, and its performance since the restart.

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Dual Mode, “Crossover” Type Tunnel Boring Machines: A Unique Solution for Mixed Ground in the Middle East

While both Hard Rock Tunnel Boring Machines (TBMs) and Earth Pressure Balance (EPB) machines have been in existence for 50 years or more, the prevalence of mixed ground tunnels can make their use problematic. In many tunnels with both sections of hard rock and softer EPB type ground, the only historical solution was to use multiple machines or sacrifice efficiency by using just one machine type. Today, Dual Mode, “Crossover” type machines are edging TBMs into new territory by employing design elements from both EPB and Hard Rock Single Shield Machines. Where multiple machine types might have once been used, a Crossover Rock/EPB machine can excavate an entire tunnel in vastly different conditions. The machine type is particularly useful in fractured and faulted weak rock where clay inseams and sections of soft ground may be present. New designs are making this versatile take on tunnelling more efficient, even at larger diameters of 12 meters or more. This paper will explore modern trends in mixed ground TBM tunnelling, including Crossover EPB/Rock Designs that could be applied to the weak/soft rock so often encountered in Middle East tunnelling. It will also look at other Crossover machines being introduced into the industry, including Crossover EPB/Slurry TBMs for tunnelling in high pressure conditions.

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Robbins Main Beam TBM Boring Cycle

Video shows how a Robbins Main Beam, or open-type, tunnel boring machine (TBM) excavates tunnels in hard rock.

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Rugged Robbins TBM and Conveyors go for Gold in Indianapolis

The News In Brief:

• The Robbins 6.2 m (20.2ft) diameter Main Beam TBM completed the Eagle Creek extension tunnel on March 5, 2015.
• The world-record-setting jobsite includes a number of unique aspects, the conveyor system being one of them. The Robbins continuous conveyor consists of 82,000 ft of belt and travels through two unprecedented 90-degree curves.
• The project was put in place to reduce the amount of raw sewage overflows in the city’s neighborhoods and clean up tributaries along the White River.

On March 5, 2015, a Robbins 6.2 m (20.2 ft) diameter Main Beam TBM finished boring a 2.8 km (9,175 ft) long extension tunnel, known as the Eagle Creek Tunnel, for the Indianapolis Deep Tunnel System in Indiana, USA. The contractor, Shea/Kiewit (S-K) JV, had much to celebrate: “I’m proud of our world records, and most of all our men and the hard work they have done as a team, working together to accomplish a project of this size,” explained Stuart Lipofsky, Project Manager, for S-K JV. “We finished the first 12.5 km (41,000 ft) [of the main tunnel] almost a year ahead of schedule. The extension added time but what is remarkable is that we were still able to finish within the original contractual dates,” continued Lipofsky. The completion of the first leg of a much larger tunnel system targets three critical CSOs that flow into the nearby White River, and will go online in 2017. The completed tunnels bring the city one step closer to achieving its consent decree with the U.S. Environmental Protection Agency (EPA), set to be achieved by 2025, to eliminate overflows into the city’s rivers.

The rebuilt Robbins hard rock TBM was first used on the 12.5 km (7.8 mi) long main tunnel, called the Deep Rock Tunnel Connector (DRTC). The new cutterhead arrived onsite in November 2012, and the machine was launched from a 76 m (250 ft) deep shaft to bore through limestone and dolomite. The TBM achieved world records in its size class of 6 to 7 m (20 to 23 ft), including “Most Feet Mined in One Day” (124.9 m/409.8 ft); “Most Feet Mined in One Week” (515.1 m/1,690 ft); and “Most Feet Mined in One Month” (1,754 m/5,755 ft). According to Tim Shutters, Construction Supervisor for project owner Citizens Energy Group, there were two main factors for the TBM’s high performance: “The first one is the very nice cutterhead provided by Robbins. It has performed very well. [Second], rock conditions are favorable for mining operations and optimal for fast production.”

Another important element that helped the speedy machine achieve a fast advance was, as Lipofsky put it, “one of the most complex continuous conveyor systems in North American tunneling construction.” The custom-built Robbins system, consisting of 25 km (82,000 ft) of belt, included horizontal and vertical conveyors for efficient muck removal. The system was the first built by Robbins to go through such sharp curves: “The belt is going through two 90-degree curves in opposite directions and S-curves in other places. It’s very unusual and amazing to see a belt system perform as well as this one did,” said Lipofsky.

Once complete, the deep tunnel project will reduce the amount of raw sewage overflows and clean up tributaries along the White River. Tim Shutters describes the environmental benefits the project will provide the Indianapolis community: “I’ve lived in Indy all of my life, and the White River has never been a focal point for the city as there is a lot of pollution. I really think that once it has been cleaned up, people will want to visit, they will swim and fish, and property values along that body of water will go up. Being able to finally utilize the river is key for us.”

After the early completion of the Eagle Creek Tunnel, the project will be moving into its next two tunneling phases. The White River Deep Tunnel will continue 8.5 km (5.3 mi) north of the completed DRTC and pump station. The Lower Pogues Run Deep Tunnel will split off 2.7 km (1.7 mi) from the White River Deep Tunnel heading east. Two additional tunnels, including Fall Creek and Pleasant Run, are anticipated to be built in 2020, and the project (27 km/17mi of tunnels in total) is expected to be fully completed by the end of 2025.

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Complimentary Webinar: A Myth Dispelled by President Lok Home

Subject: A Myth Dispelled: In Difficult Ground, the Time for Drill & Blast Excavation has Passed
Date: April 15, 2015
Time: 10:00 AM EST, 2:00 PM GMT, 2:00 PM WEST
Hosted By: Robbins
Register Now, Limited Spaces Available!

In the modern-day tunneling industry, one outdated perception remains: Traditional, tested methods are always the best. When presented with difficult ground””from fault zones to water inflows to mixed face conditions””many consultants and contractors rely on decades-old field studies and conclude that conventional excavation methods like drill and blast are the best option. With today’s Tunnel Boring Machine (TBM) technology, this assumption couldn’t be further from the truth. Modern TBMs are highly adaptable and capable of offering all of the same ground support and excavation capabilities of their conventional counterparts””most often with a safer setup and faster performance, not to mention at a lower overall cost.

In this complimentary 60-minute webinar, Robbins President Lok Home will analyze recent tunneling projects in difficult ground conditions where TBMs have proven their worth, including Turkey’s Kargi Kizilirmak Hydroelectric Project and Peru’s Olmos Trans-Andean Tunnel. At Kargi, a shielded hard rock TBM overcame incredibly difficult mixed face conditions with the help of in-tunnel machine modifications””ultimately completing the tunnel at an advance rate more than twice that of a drill and blast operation proceeding from the opposite end of the tunnel. At Olmos, the world’s second deepest civil works tunnel, a TBM ultimately succeeded at boring where drill and blast had failed: below 2,000 m of volatile volcanic rock in the Andes Mountains.

We invite you to submit your questions beforehand to marketing@robbinstbm.com to get a well-researched answer during the Q&A session at the end of the webinar.

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Announcing the Crossover Series of Robbins Dual Mode TBMs

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 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.”

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Breakthrough Robbins "Crossover" Machine Breaks Through

The News in Brief:

• The Grosvenor Decline tunnel marks the first method of a TBM being used in a coal mine in Queensland.
• The unique Crossover Rock/EPB TBM features design aspects from both hard rock Single Shield and soft ground EPB TBMs to bore through a variety of ground.
• The “Crossover” designation is new for Robbins, and will going forward be the designation for all types of Dual Mode TBMs.
• The Crossover TBM for Grosvenor was uniquely designed for excavation in conditions that included the potential for methane gas. It was designed as Class 1, Division 2 Coal Mine Compliant.
• The TBM excavated at rates fourteen times that of a traditional roadheader operation (70 m per week on average vs. 5 m per week).
• The TBM broke through into an active section of the coal mine on February 9, 2015, completing excavation of two mine access tunnels.

Full Press Release:

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 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™bout 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.

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 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.

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.

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