A crowd of crew members gathered to celebrate in front of a newly emerged hard rock TBM on December 10, 2015 in northern Norway, but their celebration was about more than just a breakthrough. The 7.2 m (23.6 ft) diameter Robbins Main Beam machine had traversed incredibly hard rock, water inflows, and more to become the first TBM in the country to break through in over 20 years.
The 7.4 km (4.6 mi) long headrace tunnel for the RÃ¸ssÃ¥ga Hydroelectric Project offered up a number of challenges to the crew. “We bored through hard, quartz-rich rock with rock strengths up to 300 MPa (43,500 psi) UCS and softer karstic limestone with water ingress,” explained Tobias Andersson, TBM Manager for contractor Leonhard Nilsen & SÃ¸nner (LNS). Despite the geological challenges, the TBM performed very well and achieved a record production of 250 m (820 ft) advance in one week, as well as a high of 54 m (177 ft) in one day. Advance rates consistently ranged from 180 to 200 m (590 to 660 ft) per week throughout the project.
The hard and abrasive rock required both fine-tuning of the disc cutters and a learning curve with regards to TBM operation. “We overcame the rock by adapting driving parameters to the different geology, cutter wear and vibrations of the machine. We had regular maintenance, but most important of all we got really good at changing the cutters, with times down to 10 minutes per cutter change, which couldn’t have been done without good team work,” said Andersson.
It was the many cutter changes that prompted the close-knit team of LNS and Robbins to look for a better solution. “Extremely hard rock (above 250 MPa/36,300 psi) will always be a great challenge for any cutter. The very special features of the rock encountered combined with the extreme hardness made us go back to the Robbins Cutter Department to develop special cutter rings for the project. These rings increased the cutter life significantly for the project and contributed to the good production,” said Sindre Log, General Manager of Robbins Norway.
The Robbins TBM was launched following Onsite First Time Assembly (OFTA) in January 2014, less than twelve months after contract signing, and was from the outset designed for hard rock conditions. A Measurement While Drilling (MWD) system was included to analyze the ground conditions ahead of the TBM, while probe drilling was done systematically throughout the project. “This is a strong and simple machine ready to tackle hard rock conditions, but also designed to handle softer rock, which allowed for fast excavation. We had good support from competent Robbins field service,” said Andersson.
After all the obstacles, it was clear that the breakthrough ceremony celebrated a triumph of teamwork as well as a new chapter for TBMs in Norway. “Our whole jobsite was gathered for the event: LNS management, representatives from Robbins, and our client Statkraft. People said it was the best breakthrough event they had seen,” said Andersson. Now that tunneling is complete, project owner Statkraft will work to commission the tunnel and fill it with water by spring 2016.
The News in Brief:
- A 3.5 m (11.5 ft) Robbins Main Beam is a hard rock veteran, with a career spanning 32 years.
- With the 6.3 km (4.0 mi) Mid-Halton Outfall Tunnel under its belt, the Robbins Main Beam will have bored nearly 30 km (18.6 mi) of tunnels.
- The refurbished TBM was beefed up with modern VFDs, electronics, and a modified cutterhead for high-capacity tunneling in hard rock.
- Contractor STRABAG is in charge of tunnel construction in Ontario, Canada, as well as the construction of two deep shafts.
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.
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 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.
“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.
Subject: What is the Total Cost of Owning a TBM?
Date: September 24, 2015
Time: 07:00 PST, 10:00 EST, 15:00 BST
Hosted By: Robbins
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Tunnel Boring Machines exist today that have excavated over 50 km (31 mi) of tunnel, and have been in operation for nearly 50 years. These workhorses have been built and rebuilt to satisfy requirements of various tunnels while their durable steel structure endures.
Today’s underground construction contractors often face a higher capital cost during the initial investment for a TBM, but what is the total cost of owning a TBM? Much more than the initial price tag must be taken into account: while a heavier TBM with durable steel structure may cost more initially, reusing it on multiple tunnels will ultimately result in substantial savings. Paying for a custom-designed machine often results in increased efficiency and faster advance rates, with the end result that the tunnel is completed on or even ahead of schedule.
In this complimentary 60-minute webinar, Robbins Vice President-Sales Doug Harding will explore the true cost of owning a TBM, considering the entire lifespan of the machine. He will draw on real project data and cost estimates to demonstrate that a machine designed for multiple tunnels will pay for itself over time.
We invite you to submit your questions beforehand firstname.lastname@example.org to get a thoughtful and well-researched answer from Doug during the Q&A session at the end of the webinar.
The News In Brief:
- A Robbins 3.96 m (13.0 ft) Main Beam TBM launched in spring 2015 to bore Hawaii’s longest tunnel.
- The 4.8 km (3.0 mi) Kaneohe-Kailua Wastewater Conveyance Tunnel is being built for the City and Council of Honolulu to stem overflows of wastewater after rain events.
- Southland/Mole JV is constructing the tunnel””the first of its scope to be built in the Hawaiian Islands.
- As of June 2015, the Robbins TBM had excavated more than 300 m (1,000 ft), and was boring at a rate of 12 to 15 m (40 to 50 ft) per day in basalt rock.
In the spring of 2015 by the idyllic shores of Oahu, a Robbins 3.96 m (13.0 ft) diameter Main Beam TBM began its long journey. The TBM started its excavation on a 4.6 km (2.8 mi) drive for a new sewer tunnel in Kaneohe, Honolulu, Hawaii, USA. The machine, nicknamed Pohakulani, meaning “Rock Girl” in Hawaiian, launched from a 23 m (74 ft) deep starter tunnel on a mission to bore through almost 4.8 km (3.0 mi) of basalt bedrock. Contractor Southland/Mole JV is building the Kaneohe-Kailua Wastewater Conveyance Tunnel for the City and Council of Honolulu, which will improve wastewater infrastructure by eliminating overflows during rain events.
The deep tunnel option was not the first design considered for the project: preliminary plans called for a smaller tunnel traveling under the bay. As Kaneohe Bay is an environmentally-sensitive area, a deep tunnel remained an attractive option. Richard Harada, of project consultant Wilson Okamoto Corporation, explains the ultimate decision: “A number of factors were considered in making the decision to build a deep tunnel including reliability, construction costs, life cycle costs, environmental impacts, constructability and qualified contractor availability.”
During the tunnel design phase, it was decided that the tunnel route should travel inland and deeper underground in order to bypass one of the few residential areas along the alignment. Designers introduced an isolated curve in the tunnel alignment of 150 m (500 ft) radius, requiring the TBM to be designed with a unique back-up system. There will also be operational procedures when crews navigate the tunnel curve, requiring the machine to be operated using half strokes rather than a full TBM stroke.
The curve is not the only unusual aspect of the tunnel; in fact, a tunnel on this scale has not been built in the Hawaiian Islands before. Everything from the logistics of the tunnel operation to pre-grouting sections ahead of the TBM for groundwater control are new to the Aloha State. Director of Southland, Tim Winn, elaborates: “There has not been a Tunnel Boring Machine of this size in the Hawaiian Islands or a tunnel of this length. The tunnel is being driven from an active Water Treatment Plant (WTP), and space is at a premium. There are also simultaneous contracts being performed there outside the scope of our work.” He adds that although there have been challenges, teamwork has been key: “Robbins Field Service has been extremely valuable during assembly and commissioning of the TBM.” As of June 2015, the TBM has excavated more than 300 m (1,000 ft), and is boring at a rate of 12 to 15 m (40 to 50 ft) per day in basalt rock. Rock bolts, steel arches, wire mesh, and ring beams are being installed as necessary.
Upon completion, the deep tunnel will enhance water treatment capabilities and further aid in ceasing non-compliant, uncontrolled or moderately treated wastewater discharges. The Main Beam TBM is estimated to end its journey in eight to ten months at the Kaneohe Wastewater Pre-Treatment Facility.
The News In Brief:
- The Robbins Remote Controlled Small Boring Unit (SBU-RC) is a new type of boring machine capable of excavating small diameter hard rock tunnels at long distances, on line and grade.
- The SBU-RC is currently manufactured in the 36-inch (900 mm) diameter range, but could be designed as small as 30 inches (750 mm) in diameter.
- The SBU-RC features a smart guidance system for pinpoint steering accuracy and is controlled from an operator’s station on the surface.
- Muck removal is accomplished through a vacuum system, making the Robbins SBU-RC more cost effective than MTBMs requiring slurry and cleaning plants onsite.
- A Robbins 36-inch (900 mm) SBU-RC completed a critical hard rock crossing below railroad tracks two weeks early in Bend, Oregon, USA, breaking through on May 5, 2015.
- The SBU-RC holed through on line and grade after achieving up to 50 ft (15 m) of advance per day in abrasive basalt rock up to 7,000 psi (48 MPa) UCS
In Bend, Oregon, USA, local contractor Stadeli Boring & Tunneling had a unique set of circumstances for a new gravity sewer interceptor. “We had a contract with general contractor Taylor NW to furnish and install 323 ft (98 m) of 36-inch (900 mm) steel casing under railroad tracks. Line and grade were very crucial, and the tolerances were very close. We had to be right on,” said Larry Stadeli, president and owner of Stadeli Boring & Tunneling. In addition to those parameters, the job was also in solid rock.
Fortunately, there was a solution available to help them. The contractor turned to The Robbins Company, a business that they had worked with many times over the years for their Small Boring Units (SBUs). Stadeli first contacted Robbins 10 years ago to rent a 30-inch standard Small Boring Unit (SBU-A), and has since rented dozens more. The company currently owns two SBU-As, but their Bend, Oregon job required precision guidance systems that their SBU-As lacked. “We met with Robbins in Ohio and told them what our needs were. They felt like their 36-inch (900 mm) prototype machine, which they had tested at one other job in Oman, would be a good fit. They listened to what we were wanting and needing to have done,” said Stadeli.
At Robbins, Kenny Clever, SBU Sales Manager, and a group of engineers were honing the prototype machine that fit the bill. Known as the SBU-RC, for Remote Controlled Small Boring Unit, the machine was equipped with a smart guidance system by TACS. The guidance system could show an operator projections of the future bore path so steering corrections could be made before the machine was ever out of line and grade. The feature was critical for the crossing below the railroad tracks, which could not be shut down if problems occurred.
The SBU-RC is currently manufactured in the 36-inch (900 mm) diameter range, but could be designed as small as 30 inches (750 mm). The machine operates much like a Motorized SBU (SBU-M) with a circular cutterhead and cutting tools that can excavate hard rock or mixed ground conditions. An in-shield drive motor provides torque to the cutterhead, while a pipe jacking system or Auger Boring Machine (ABM) provides thrust. Clever explains the biggest differences: “There is no manned entry. It eliminates the human element, so it is safer and there is no need for ventilation and other things required when you have a worker in the tunnel. With its guidance system, it also eliminates much of the risk on line-and-grade-critical bores.” Muck removal is accomplished via a vacuum system connected to a vacuum truck. The machine is capable of excavating hard rock and mixed ground crossings up to 500 ft (150 m) long, depending on conditions.
While microtunneling machines have been used on jobs such as these, Clever cites key advantages for the SBU-RC: “There is no slurry to mix or contend with. With MTBMs the slurry must be cleaned, pumped, and treated. With the SBU-RC there is a clean and dry pit, with no spoils to remove. The way the SBU-RC operates is much more cost effective. The SBU-RC is also available for lease; MTBMs are often not cost effective to lease for contractors trying to stay competitive.
The SBU-RC was delivered on April 14, 2015, and was lowered into a launch pit 26 ft (8 m) deep. There were several early tweaks to the setup including a larger vacuum truck that improved suction, and some modifications to the cutterhead including grill bars. These modifications were expected and will be incorporated into later versions of the machine.
The machine began boring in volcanic basalt rock that was full of fissures, fractures, and rubble pockets between 5,000 and 7,000 psi (34 to 48 MPa) UCS. While the start-up was rough going, crews quickly began getting rates of 20 ft (6 m) per day. “As we got used to the machine we went up to 40 ft (12 m), and one day we even got 50 ft (15 m). We were able to cut off a couple weeks of our schedule time. Taylor NW was very pleased about it. When you look down the pipe now after it’s finished, it looks like a rifle barrel. There is no sag, it’s all in one straight line,” said Stadeli.
The early completion by the SBU-RC delighted the City of Bend and all those involved. “I think the SBU-RC is an exciting piece of equipment that has been compressed into a 36-inch size. To make it all work it is very compact. It’s impressive that the components have been sized down and it still works so efficiently,” said Stadeli.
With the clear success in Oregon, Robbins is looking to lease the machine on more projects and expand their offerings. As Clever put it: “Finally our industry has provided a small diameter, on-line-and-grade machine that will drill in solid rock at distance. This is a game changer, it will be the most innovative piece of equipment in our industry for a long time.”
Is there a better way to build a Tunnel Boring Machine (TBM) that can benefit all parties involved? For decades TBMs have traditionally been assembled in factories, where the components are assembled and tested, then disassembled and shipped to the jobsite. Delivery of a machine can often be the critical path affecting project schedule, cost, manpower, and other factors. Onsite First Time Assembly (OFTA) has been developed and used on dozens of projects around the world to pass on cost and time benefits to contractors working on fast-paced projects with tight schedules. The use of OFTA is increasing, allowing for TBMs to be initially assembled at the jobsite, and cutting out extra shipping and disassembly steps. This paper will analyze the reasons for shop assembly vs. onsite assembly, determining the ultimate benefits and drawbacks of each. The paper will also draw quantitative comparisons in terms of time and money, as well as differences in carbon emissions, energy, and manpower requirements. The paper will conclude with a discussion on trends in TBM assembly today and where the future is headed when building these complex tunneling machines.
Subject: Fast-Track Your Mine with Proven TBM Technology
Date: June 24, 2015
Time: 13:00 PST, 16:00 EST, 06:00 AEST
Hosted By: Robbins
Register Now, Limited Spaces Available!
Second Option: Pre-Recorded Broadcast
Date: June 25, 2015
Time: 07:00 PST, 10:00 EST, 15:00 BST, 16:00 CEST
Hosted By: Robbins
Register Now, Limited Spaces Available!
Today’s mine development projects are no longer being done from the surface. Worldwide, easily accessible ore deposits have been spent, requiring mines to aim for deeper ore bodies, often kilometers underground, to keep operations viable.
This changing mine environment brings a need for access tunnels, first to reach the ore, then to provide long-term muck haulage. Tunnel boring machines provide efficient, safe, and fast access to those ore bodies. Mines around the world are accustomed to methods such as drill & blast, roadheader, and other types of conventional excavation. However, TBMs have been proven on multiple projects to complete tunnels two to three times faster than drill and blast; when considering roadheaders that number is often 10 times faster.
In this complimentary 60-minute webinar, Ryan Gratias, Project Engineer at Robbins and Adam Foulstone, General Manager-Grosvenor for mining company Anglo American, will discuss the changing face of the worldwide mining industry. From machine design to application and real-world examples, Gratias will prove that early adopters of the TBM method will be able to better meet increased demand and extend the life of their mine. Foulstone will discuss the recent use of a Crossover (XRE) TBM at the Grosvenor Decline Tunnel in Australia™ wildly successful use of a TBM that resulted in access tunnels bored 14 times faster than the traditionally-used roadheader method.
We invite you to submit your questions beforehand to email@example.com to get a well-researched answer during the Q&A session at the end of the webinar.
Multiple fault zones and squeezing ground requiring extensive bypass tunneling were just a few of the challenges to be overcome to successfully complete Turkey’s Kargı Kızılırmak Hydroelectric Project. Launched into poor geology in 2012, the 10 m Double Shield TBM experienced delays to the project that forced team members to find innovative solutions that included major in-tunnel modifications to the machine. In the first 2 km of boring a total of seven bypass tunnels were needed to free the TBM from collapsed ground. The cutterhead stalled on numerous occasions as the conditions varied widely from solid rock to running ground. Small and wide faults along the alignment added another level of complexity, as the excavation was located very close to the North Anatolian fault line in Turkey’s relatively recent rock formations.
Due to the delays, it was decided to take what was an originally 11.8 km TBM driven tunnel, and reduce it to 7.8 km with the final 4 km being excavated by drill and blast. The contractor, owner, consultants and Robbins engineers worked together to generate solutions to improve progress in the difficult conditions. A custom-built canopy drill and positioner was installed for the contractor to allow pipe tube support installation through the forward shield. Drilled to a distance of up to 10 m ahead of the cutterhead, 90mm diameter pipe tubes provided extra support across the top 120-140° degrees at the tunnel crown. Injection of resins and grouting protected against collapse at the crown while excavating through soft ground. As a result of successful use of the probe drilling techniques, the contractor was able to measure and back fill cavity heights above the cutterhead in some fault zones to over 30 m and in addition help detect loose soil seams and fractured rock ahead of the face.
This paper will go over the extreme challenges at the Kargı project, as well as the dramatic improvement in advance rates and the ultimately successful breakthrough in July 2014. A comparison will also be made with the site conditions and advance rates at the drill and blast tunnel to determine when each method of excavation is best used.
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.
- Use of a Tunnel Boring Machine on Nepal’s First and Second TBM-Driven Tunnels
- Record-Setting Large Diameter Mixed Ground Tunneling in Turkey: The Eşme-Salihli Railway Tunnel
- Lessons Learned During Excavation of the Incredibly Challenging Yin Han Ji Wei Water Diversion Tunnel
- Record-Setting Tunnel Boring Below Lake Ontario at the Ashbridges Bay Outfall Tunnel
- Enhanced Probe Drilling & Pre-Grouting on Hard Rock TBMs