Visit Robbins at stand 727, near the entrance of the Washington State Convention & Trade Center. Our stand will feature interactive iPads and videos, and will be staffed by knowledgeable Robbins employees who welcome the opportunity to speak with you. We look forward to seeing you in Seattle.

Stillwater Mine
Three Robbins Main Beam TBMs have been contracted to bore the Stillwater Mine in Nye, Montana. The most recent machine is an 18 foot (5.5 meter) Main Beam that will excavate an exploratory tunnel to map a platinum and palladium reef.

Robbins will be exhibiting at stand no. 14 in the exhibit hall of the Centro Asturiano de México AC. Our stand will feature interactive iPads and videos, light refreshments, and will be staffed by knowledgeable international Robbins employees.

Mexico City Metro Line 12
A 10.2 m Robbins EPB – the largest to ever bore in Mexico – is excavating a 24 km long route for the Mexico City Metro, which will pass through 22 new stations between Tlahuac and Mixcoac. Breakthrough for Line 12 will occur the second week of February, helping alleviate some of the city’s traffic congestion.

Emisor Oriente
Mexico’s most critical infrastructure project, a 62 km long wastewater line, Emisor Oriente, is being constructed to help increase Mexico City’s wastewater capacity. An 8.93 m Robbins EPB is currently boring Lot 1 to facilitate the delay of a Herrenknecht machine that could not proceed because of a flood. The EPB will soon be joined by two more Robbins EPBs of the same diameter, which will bore Lots 3 and 4. The EPB boring Lot 1 will then be moved to Lot 5, where it will complete its originally scheduled bore.

Myth No. 1 – It will be a disaster if the parts don’t fit together on the job site!  That is why a full factory assembly is required.

This myth doesn’t take into account three factors:

1.  Partial assembly: Major sub-assemblies are pre-assembled in the factory.   The main bearing and seal assembly, for example, is fully factory assembled.  It is only the major parts that may not be pre-assembled.  However, in many cases, we pre-fit the pieces; forward shield to outer telescopic shield, outer to inner telescopic, inner telescopic to gripper shield, and so on for a double shield machine.   So the part fit-up is checked but the entire machine is not put together in the factory.

Major components are checked in the factory to ensure fit up.

2.  Modern measurement devices:  In those cases where it is not possible to pre-fit two pieces in the factory, we can use modern Coordinate Measuring Machines (CMMs) or “Laser Trackers” to take precise measurements of both pieces to insure fit up when they meet in the field.

A Robbins employee uses a CMM device in the Ohio manufacturing facility.

3.  In-field repairs:  When an offshore oil rig has a component failure do they disassemble it and take it to the mainland for repairs?  When repairs are required on hydroelectric turbines and generators, do they always take the big parts to a machine shop to repair?  No, they do not.  Many repairs of large scale equipment are made in situ, wherever the plant is located.  If it is discovered at the job site that a component has been mis-machined / manufactured it is most likely a minor error (remember the CMM measurements and component fit-ups in factory partial assembly) and repair can be effected on the piece in place at the job site.  In Robbins experience, this has always been the case and such repairs have been carried out when discovered on site and without impact to final startup schedule.

Myth No. 2 – The labor cost on an underground job site is far higher than labor cost in a factory.  It will cost far more money and time to assemble the machine on site for the first time.

OFTA Myth No. 2 leads to a wrong conclusion regarding cost, and fails to examine fully the potential benefits.

1.  Cost: This above statement is generally true; however, it does not necessarily follow from this statement that money will be saved by having a factory assembly plus a job site assembly.  Robbins history with in-factory and OFTA assembly reveals the following:

Traditional Factory Assembly

• Full factory assembly hours:  X hours
• On-site assembly of a fully factory assembled machine: 0.5X hours

OFTA Method

• Partial factory assembly for OFTA delivery: 0.5X hours
• OFTA site assembly of a partial factory assembled machine: 0.7X hours

Where the value of X is dependent upon the size and type of TBM as well as the complexity of the backup system.

If we assume that the cost of labor on the job site is twice the cost in the factory, then we can use $100/ hour for the job site and $50 / hour for the factory.  The total cost for the two methods is then:

• Traditional method cost = X hours ($50/hour) + 0.5X hours ($100/hour) = $100X
• OFTA method cost = 0.5X hours ($50/hour) + 0.7X hours ($100/hour) = $95X

In short, the total costs are nearly the same, or perhaps with some savings in favor of the OFTA method.

2.  Schedule: Another flaw with Myth No. 2 is that it does not consider a large potential benefit: the savings in schedule possible with the OFTA method.  By not completely assembling the TBM in the factory, it is possible to deliver a working TBM at the job site one to two and a half months earlier than with a traditional full-factory assembly and delivery.  This is a significant savings for most projects, when the site assembly can be done at this early stage.

OFTA for the 14.4 m diameter Niagara TBM was completed in four months, saving an estimated four to five months on the delivery schedule.

3.  Training of site personnel:  Another potential benefit that Myth No. 2 does not address is that of training.  The contractor’s site personnel who are involved with OFTA assembly and testing get far more training due to the additional hours spent on the assembly and testing, and the larger Robbins crew present to assist and advise.  Robbins’ experience indicates that contractors who opt for OFTA deliveries are frequently capable of taking over the full operation and maintenance of their new TBM much quicker than contractors who opt for a traditional delivery.   This is due to the much deeper knowledge the contractor’s personnel gain during the OFTA assembly and testing.

Site personnel take part in the assembly of a Double Shield TBM in India.

In summary, the question to be asked when making the decision to use OFTA or go for a traditional factory assembly is: What are the potential risks and what are the potential rewards?  One must examine all potentials of the OFTA scenario, pros and cons, to come to the correct solution.   I’m not claiming that an OFTA scenario is correct for every project.   For example, if the start of boring of the tunnel is not on the critical path for the project and the TBM is a smaller diameter unit, it might be advisable to allow a full factory assembly. That way, when the job site is finally ready for the machine, it can be assembled a bit quicker on site.  Again, if the start of boring is not on the critical path and the labor cost difference between job site and factory is larger (e.g., job site is in Finland, TBM factory is in China), then it could be that a full factory assembly can be justified on a cost only basis.  However, in nearly every case when the start of boring the tunnel is on the critical path, then the faster delivery possible by OFTA is clearly favorable.

The biggest impediment to more widespread use of OFTA is limited thinking: looking at the potential risks without looking at the potential rewards.  Tunneling itself is fraught with risk, yet contractors take on jobs everyday due to the potential rewards.  OFTA is deserving of a similar analysis.

About the Author

Joe Roby (B.S., Mechanical Engineering, University of Washington) has worked in the tunneling industry for more than 20 years. He started at The Robbins Company as a stress analyst specializing in finite element analysis of complex structures. Subsequently he was a member of the 19-inch cutter development team. For five years he was managing director of Robbins refurbished and leased TBM division. He has authored many technical papers for conferences and industry publications on subjects ranging from cutters to TBM assembly and rebuilding practices. Today he serves as Robbins’ Vice President – Production & Logistics.

“South America is one of the most promising future markets with many upcoming projects, strong competition and potential for manufacturing opportunities. Setting up an office in this region was important to us because a close and constant approach with our clients is essential in the Latin American market,” said Rolando Justa, Managing Director of Robbins South America. The subsidiary was established to augment the growing regional market and provide project management services, TBM field service, sales functions and technical support to our clients. The office will work closely with the Robbins main offices in the United States as well as our offices in Spain and Latin America.

Robbins has 14 offices worldwide with more growth planned for the future, each providing support for local projects and growing markets.  “The benefit of having local support is immeasurable – customers will have an immediate response to field service issues, a conduit for our worldwide resources, and Robbins employees with whom they can communicate directly in their native language,” said Doug Harding, Robbins Vice President of Sales-Solon, Ohio.

Robbins South America Contact Information:

Robbins South America
Avd 11 de Septiembre 1881
Oficina 1515
Providencia, Santiago de Chile
Chile
Phone: +56 9 61353776
Email: justar@robbinstbm.com

The 12.5 km (7.7 mi) of TBM-driven section is part of a larger scheme that will transfer water from the Huancabamba River on the Eastern side of the Andes to drought-ridden areas on the Pacific Ocean Watershed.  To complete the connection, the Robbins machine had to pass under cover up to 2,000 m (1.2 mi), which caused tremendous rock stresses resulting in more than 16,000 rock bursting events—about 17% of which were classified as severe. “I am satisfied with the performance of the machine, it was very powerful and performed well in the high-frequency rock bursting conditions,” said Mr. Hiroshi Handa, Production Manager for Odebrecht.

The extreme nature of the geology—andesite, dacite, tuff, schist, and pyroclastic breccias up to 250 MPa UCS—was unforeseen and required in-tunnel machine modifications as rock bursting became more severe.  Crews removed the roof shield fingers and installed the McNally Support System, manufactured by Robbins under license from C&M McNally.  The system consists of steel slats anchored to the roof of the tunnel by steel straps and rock bolts, effectively containing loose and unstable rock.  These steel slats form an umbrella that allows the crew to work in a safe environment.  Other changes included reinforcements to the cutterhead, and relocating the platforms and operator’s cab.

The modifications were successful, and no serious injuries occurred during continued rock bursting, in part because of a pre-drilling and sequential boring policy developed by Odebrecht.  During a push, workers exited the area directly behind the cutterhead support and stayed 40 m back from the face for a period of 30 minutes—allowing rock deformations to occur while protecting workers.

“I am proud to have an extraordinary working team—despite all of the difficulties and challenges they never lost confidence.  There were days with advance rates of 35 m (115 ft), and days with rates of 50 cm (20 in) in the most difficult conditions. The most important thing is that the designer, TBM manufacturer and contractor worked together to make the necessary adjustments to the TBM,” said Mr. Handa.

See the extreme rock bursting conditions the crew encountered at Olmos in our video clip:

http://www.youtube.com/watch?v=Nn79zHg8yvE

In Autumn 2011, Robbins set a distance record for a hard rock machine below 2 m in diameter. The 72 inch (1.8 m) Double Shield Rockhead excavated a 2,014 ft (614 m) tunnel for contractor Midwest Mole Inc. in Cincinnati, Ohio. The machine was fitted with a mixed ground cutterhead using disc cutters and carbide bits.

Join Robbins at Booth 1345 to learn more about our recent tunneling feats and innovations. Interactive iPads and videos will be on display with featured projects and information. Experts from across the nation will be on hand to address all inquires.

“The performance of the two machines was perfect, and the project owner has praised our excavation,” said Mr. Zhao Donghua, Project Manager for contractor CRCC Bureau 11.  The 11th Bureau and project owner Zhengzhou Metro Company held a grand ceremony for the final EPB breakthrough on November 16.  The parallel 3.6 km (2.2 mi) tunnels are widely regarded as the most difficult section of the metro, with low cover of 7 m (23 ft) in a section of permeable, water-bearing soils below Xiliu Lake.

The Robbins machines were launched in November and December 2010, and achieved two intermediate breakthroughs into cut and cover station sites between Tongpai Road and Kaixuan Road station along the way.  Ground for much of the tunneling was under approximately 8 m (26 ft) of cover in soft and powdery soils, and below building foundations and a highway interchange.

Daily advance rates as high as 23 rings (34.5 m / 113 ft) were achieved despite these challenges, including special measures below Xiliu Lake.  Crews carefully maintained earth pressures of between 1.1 and 1.3 bar while boring at a low cutterhead speed of 1 RPM below the lake, reducing advance rates in this section. Settlement levels remained within limits during the entire drive.

CRCC Bureau 11 already has new projects lined up for the machines, which have been removed from the station sites.  “We will utilize one EPB at the Beijing Metro project, the other machine will stay in Zhengzhou for future metro contracts,” said Mr. Donghua.

Zhengzhou, a city of 7 million people, is planned to become a center for rail commerce in China.  Up to four metro lines will be built in Zhengzhou, while freight lines traveling between Beijing and Guangzhou (North-South), and between Xuzhou and Lanzhou (East-West), will eventually intersect in the city.   Once complete in 2013, Line 1 of Zhengzhou Metro will include 26 km (16 mi) of tunnel and 22 stations.

Day 1

On a good day with light traffic, the jobsite is about an hour’s drive away from the Distrito Federal, the downtown zone of Mexico’s capital city.  Our first day, I noticed how the high rise buildings and restaurants slowly dissolved into ramshackle huts as we drove further from the city to an area known as Ecatepec.  Approaching the site, we crossed a bridge in our SUV that spanned an extremely slow moving grayish brown river (more about this soon).

The "river" flowing outside Mexico City.

It was a warm day in June, Mexico’s rainy season, which is quite different from the rain in my home town of Seattle in the U.S.  Each day during the rainy season, the morning dawns sunny and warm–but by 4:00 in the afternoon a torrential downpour begins.  The water floods city streets throughout Mexico City, whose storm drains can’t handle the sudden inundation.  Sometimes the rain only lasts a few minutes, and sometimes it goes for longer.  The water eventually runs into rivers like the one we crossed by the jobsite, creating flooding risks.

We exited our SUV at the Lot 1 shaft and were greeted by several Robbins Field Service guys, including our Field Service Manager for the Americas, Jeremy Pinkham.  I was excited to learn more about the TEO project, where we have three EPB machines among six TBMs that are excavating an epic 62 km (39 mi) long wastewater tunnel. The tunnel will feed into the country’s largest water treatment plant, which is currently being built.

The morning of the first day, at the Lot 1 Emisor Oriente site.

As Jeremy and the group walked towards the shaft to be lowered down the elevator, I was struck by a smell—something akin to a vast field of poorly maintained port-a-potties.  I asked Jeremy about the Robbins machine, which was originally intended for Lot 5 but had been fast tracked to bore part of the tunnel section at Lot 1.  I was wondering why this particular section had been deemed top priority.  “Did you see that river just a few meters away from our jobsite?” he asked. “Most rivers, when you throw a stone in, it splashes or skips and then sinks.  This one, you throw a stone in and it just goes ‘plop’, then sits there.”  It was only then that I realized that this “river” was El Gran Canal, Mexico City’s infamous open sewer originally commissioned in 1910 by President Porfirio Díaz.

The Robbins guys as well as engineers from the Lot 1 contractor Ingenieros Civiles Asociados (ICA) then explained to me that the canal in this section, lined with shacks, was prone to flooding during each rainy season due to a loss of its slope.  The effects on the people and infrastructure were severe, so the National Water Commission (CONAGUA) had fast-tracked Lot 1.  A pumping station would be put in and the first section of tunnel sealed off so that wastewater from this area could be pumped into a section of the canal downstream that still maintained its negative slope.  I was beginning to realize the importance and urgency of this project!

The guys gave us a tour of the TBM being assembled at the bottom of the shaft, which was specially designed for high pressure conditions under the water table.

Looking up from the bottom of the Lot 1 shaft where the Robbins machine was being assembled.

Robbins employees on the Lot 1 EPB. From left to right: Andrei Olivares, Robbins Project Engineer; Jeremy Pinkham, Field Service Manager - The Americas; Roberto Gonzalez, General Manager, Robbins Mexico

On the ride home that day we were hit by a particularly nasty rainstorm that went on for several hours.  I learned via the local news later on that the very roads we had driven on to get to the jobsite were now flooded with wastewater and impassable—apparently a regular yet extremely concerning event.

Day 2

The next day we went to CONAGUA’s offices to speak with José Miguel Guevara, General Supply Coordinator for Potable Water and Sanitation.  He spoke with us about the massive scope of Emisor Oriente—a project that could improve the lives of over 20 million people in the area by increasing wastewater capacity by 20% during each rainy season. The new pipeline will bolster current wastewater lines (both El Gran Canal and Emisor Central—a pipeline built in 1964) that have lost their slope due to Mexico City’s sinking lake clays.

Roland Herr, editor of Tunnel magazine (left) talks with Sr. Guevara (right) in the CONAGUA office.

While Guevara was optimistic, he admitted that health problems caused by El Gran Canal were numerous for the people living on its banks.  When asked about future plans, he expressed grave concern that funds were not currently sufficient for a covered option to the open waterway.  “At this moment,” said Guevara, “The Valley of Mexico is vulnerable.  Our new treatment plant will treat 60% of the area’s water, but we need more alternatives as well.  We are working on pieces to the problem, but the problem is not solved yet.”

With Emisor Oriente scheduled to be complete in 2014, I am hopeful that at least some of those problems will be alleviated.  This is a great example of the magnitude that civil engineering works have on societies.  I for one am proud that Robbins has a part in this monumental solution to an age old problem.

The fifth and longest of seven tunnels at the Shayler Run Segment C Sewer Replacement Project pushes the limits of small diameter tunneling. “One of the only limitations on distance is ventilation inside the tunnel. Our ventilation has a limited duct diameter due to the small size of the tunnel.   We can adequately ventilate 600 m (2,000 ft) tunnels, but we would need larger fans for anything longer,” said Steve Abernathy, Vice President of Operations for contractor Midwest Mole, Inc.

The distance of the individual bores is not the only challenge—the vertical alignment changes over the course of tunneling by 54 m (180 ft), resulting in soft shale and limestone at the outset that gives way to harder shale and limestone deeper underground.

Robbins designed the unique tunneling machine for these conditions, with a mixed ground cutterhead for five of the seven bores. A hard rock cutterhead mounted with 11.5 inch disc cutters will be used for the last two in harder rock.

“We finally had to change some of the 6.5 inch diameter cutters on the mixed ground cutterhead during this drive—we haven’t had to do that for any of the other bores.  The ground is definitely tougher,” said Abernathy of the fifth drive.  After hole through, the crew switched to the hard rock cutterhead for the sixth, 319 m (1,046 ft) long bore.

As the machine excavates, crews adjust the line and grade continuously from an in-shield operator’s console.  Articulation cylinders allow for adjustments, while the machine’s position is monitored with a laser targeting system.  The self-propelled Double Shield Rockhead also allows for installation of a primary liner, in this case ring beam and board, from within the tail shield.  Even with liner installation, production rates have been high—up to 21 m (70 ft) in one 12-hour shift, and 12 to 18 m (40 to 60 ft)  per shift on average.

The entire 2,870 m (9,416 ft) pipeline is being constructed for the Clermont County, Ohio Water Resources Department.  Once complete, the USD $15 million project will upgrade an exposed sewer system and protect an area surrounding environmentally-sensitive Shayler Creek.  All tunneling is expected to be complete in mid-2012.

Project Overview

In June and July 2010, commencement of Xi’an’s Metro Line 1 began with the launch of two Robbins machines from Changlepo towards Wanshou Road Station—the first TBMs tunneling on the project.

The city’s 26.4 km metro Line 1 will run from north to south through the downtown area.  Ten TBMs, including two 6.2 m diameter Robbins EPBs, are currently excavating the new rail route, which travels directly below some of Xi’an’s most sensitive heritage sites.

The Robbins EPBs are excavating Lot 12 of Line 1 for the 11^th Bureau of China Railway Construction Corporation (CRCC).  The parallel 3.6 km tunnels pass through four cut and cover station sites—Changlepo, Wanshou Road, Kangfu Road, and Jinhua Road—under shallow cover ranging from 8 to 22 m. The two TBMs were the first to start excavation on Line 1, and were followed by eight other machines excavating their respective lots. The Robbins EPBs are on track to cut traffic times in the 3,100 year old city, well known for its cultural artifacts including the terra cotta warriors.

A total supply contract was signed with China Railway 11th Engineering Bureau Group Limited in June 2009.  The second machine assembly was completed in April 2010 at a nearby manufacturing facility in Chengdu before being shipped to the jobsite.

Geology

Both Robbins machines are optimized for geology including sand, abrasive pebbles and clay with significant ground water.  Spoke-type cutterheads and 800 mm (32 in) diameter shaft-type screw conveyors will aid in efficient advance while maintaining a water-tight seal and balanced pressure.

Tunnel Excavation

The Lot 12 section was located in a densely urban area, with the tunnels traveling below a college, a hospital, and a marketplace. Crews continuously monitored the excavation rate and overall muck removal volume, by adjusting the thrust force, advance rate, and screw conveyor speed, while keeping the cutterhead speed low, at 1 rotation per minute. Sections of collapsible, water bearing soils were also present in early sections of the tunnel alignment.  Crews approached these sections with similar measures, including strict earth pressure control in the mixing chamber, paired with injection of bentonite and water for soil conditioning.

Tunnelling is made even more complex by a city-wide ordinance limiting settlement to ± 15 mm; significantly less than the 25 mm limit that is typical of most Chinese tunnelling projects.  The strict settlement guidelines, implemented out of caution due to the ancient structures, required specialized designs for the two Robbins EPBs.

The last intermediate breakthrough, at Jinhua Road station, occurred on July 28, 2011.  Advance rates for the Left Line EPB have been good—up to 579 m (386 rings) per month and 36 m (24 rings) per day.  Planned maintenance was performed while in the cut and cover area, such as changing of cutters and tail seal brushes as well as checkups of the hydraulic system and electrical system.  Semi-segment rings consisting of the invert and two segments were installed to allow the machine to ‘walk’ through the 140 m long station site.

Advance rates for the Right Line machine have been similarly high—up to 453 m (302 rings) per month and 39 m (26 rings) per day.  Settlement has been kept below 15 mm with an average settlement of 5 mm. Tunneling is expected to be complete in November 2011 for the Left Line machine, and in December for the Right Line.

By summer 2011, one machine had recently completed its second section of tunneling between Wanshou Road and Jinhua Road, and the other was on its last section between Jinhua Road and Kangfu Road in layered loess conditions.

The machines are currently on track to complete tunneling in Autumn 2011.  Once online in 2013, the 26.4 km (16.4 mi) metro Line 1 will reduce traffic times across the city from well over one hour to 39 minutes.

Updates of this project will be posted as boring continues.