Author: Robbins

"Rock Girl" Revs Up

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.

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Remotely Controlled SBU set to Revolutionize the Industry

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.”

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Crossover TBM breakthrough at Grosvenor Coal Mine

Provided courtesy of Anglo American, this video clip shows the 2015 breakthrough of a Robbins Crossover (XRE) TBM in the Grosvenor Coal Mine, Moranbah, Australia.

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To Build a Tunnel Boring Machine: Why Assembly on Location is the Next Big Advancement

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.

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Fast-Track Your Mine with Proven TBM Technology

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 webinars@robbinstbm.com to get a well-researched answer during the Q&A session at the end of the webinar.

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Extreme Excavation in Fault Zones and Squeezing Ground at the Kargi HEPP in Turkey

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.

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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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