Author: Robbins

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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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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