Author: Sarah Crawford

UCT 2018

Event Name: Underground Construction Technology (UCT) 2018
Dates: January 30-February 1, 2018
Location: New Orleans, LA, USA
Venue: Ernest N. Morial Convention Center

The Robbins Company will be attending Underground Construction Technology 2018 January 30 through February 1. Be sure to visit our booth to learn more about Robbins Small Boring Units (SBUs)—the most cost effective and time efficient way to bore through hard rock.

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Tunnel Turkey 2017

Event Name: Tunnel Turkey 2017
Dates: December 2-3, 2017
Location: Istanbul, Turkey
Venue: Wyndham Grand Istanbul Levent Hotel

The Robbins Company will be exhibiting at the 2017 International Tunneling Symposium, also known as Tunnel Turkey, in Istanbul December 2-3. In keeping with this year’s theme, “Challenges in Tunneling,” stop by stand S-4 to learn more about how Robbins overcomes our own challenging projects.

During the conference, be sure to attend, “Use of dual mode, crossover TBM to excavate challenging geology at Mexico City’s Emisor Poniente II Waste Water Tunnel” presented by Robbins Public Relations Manager, Desiree Willis. The presentation will take place on Saturday, December 2 at 2:00 pm.

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Boring the Blue Mountains: The Inside Story on the World’s Fastest TBM

Over 20 years ago, a Robbins open-type machine set three world records while tunneling in the picturesque Blue Mountains in Australia. You may be asking yourself, why is this significant? Why drudge up a project that is surely outdated at this point in our industry’s history? The fact of the matter is, two decades have passed and the Robbins open-type TBM chosen for this project is still considered to be the world’s fastest TBM.

Project Background

In 1993, the 3.4 m (11 ft) diameter TBM was chosen to bore two sewage tunnels in the Blue Mountains near Sydney, Australia. At the time, there had been a rapid expansion of urban developments within the Blue Mountain National Park, causing an influx of pollution to enter streams as the result of septic tank runoff and outdated sewage treatment plants.

The Blue Mountains Sewage Transfer Project comprised of approximately 40 km (25 mi) of tunnels, two of which were TBM-driven using the Robbins machine. The first, the Katoomba Carrier tunnel, was 13.4 km (8.3 mi) long and the second, the Lawson Carrier, was 3.5 km (2.1 mi) long. While the Lawson Carrier tunnel was finished five weeks prior to the expected completion date, it was during the Katoomba Carrier tunnel that all three records were set. During excavation the machine set the following world records: best day of 172.4 m (565.6 ft), best week of 702.8 m (2,305.7 ft), and a best monthly average of 1,189 m (39,000 ft) within its size range of 3 to 4 m (9.8 to 13.1 ft) diameter machine. Two of those records—the best day and best week—are the fastest ever recorded and have yet to be surpassed by any TBM of any size.

Custom Machine Design

There were many factors that played into this machine’s success—the system utilized on this project required a well-planned design, careful operation, and regular maintenance. As many people involved in tunneling know, choosing the right equipment for the geology can make or break a project. Detailed empirical data allowed the contractor to accurately predict what kind of ground they would encounter and prepare accordingly. The National Park is located within the Triassic Sydney Sedimentary Basin and is comprised primarily of sandstones and claystones. Anticipating this geology, the 3.4 m (11 ft) diameter machine’s cutterhead was dressed with 25 Robbins 17-inch diameter disc cutters designed for soft yet abrasive rock formations.

Logistics

The 13.4 km (8.3 mi) long Katoomba Carrier tunnel was originally planned to comprise of multiple short tunnels, several kilometers in length each, with intermittent portals to shorten drives. Ultimately it was decided to make the project one continuous tunnel, which led to higher advance rates and deemed it—at the time—the longest single-drive TBM tunnel. Not only did this change save time, but it also allowed boring to be less disruptive to the landscape.

Continuous Conveyor

In addition, the project was the first in Australia to utilize a continuous conveyor system. Due to the length of the tunnel, the use of traditional muck cars for muck removal would have taken too much time and were seen as an inadequate solution. The 106-m (347.8 ft) long system boosted production rates, with a best day of 1,565 m³ (55,267 ft³) of in-situ material removed from the Katoomba tunnel.

Good Geology

Ground support throughout the tunnel comprised of a combination of resin grouted bolts, mesh, steel straps and steel sets. In the sturdier sandstone, however, the tunnel was left largely unlined and instead shotcrete was applied to areas of poorer, softer rock.

As boring progressed, the sandstone proved to be softer than expected. Instead of the predicted average of 80 MPa ranging from 20 MPa to 150 MPa, it averaged 40 MPa to 50 MPa with a range of 10 MPa to 100 MPa. This ideal material could also have contributed to the Robbins machine’s record breaking results and its early breakthrough, which occurred nine months ahead of schedule.

Exceeding Expectations

The Robbins Mk 12C’s performance on the tunnel boring portion of the project substantially surpassed all expectations. Not only did it set the previously mentioned world tunneling records, but it also helped the project as a whole finish 17 months ahead of schedule, saving not only on time but on significant financial costs.

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Complimentary Webinar: Reducing Risk—How to Manage the Unknown in TBM Tunneling

Let’s face it: tunneling projects are inherently risky.  The actual geology can harbor unforeseen conditions even with rigorous testing, and even when a highly-qualified consulting company creates the Geotechnical Baseline Report. In TBM-driven tunnels, the machine and the crew operating it are key components of the risk management strategy. So, how can we ensure that the tunneling operation is done effectively as often as possible?

In this complimentary 60-minute webinar from the manufacturer perspective, Robbins Chief Engineer Dennis Ofiara and Project Engineer Elisa Comis will explore that question, delving into contract structure, TBM design, case studies, and more to find the answer. Whether you’re a contractor operating the TBM, a consultant specifying the equipment, or an owner with an upcoming project, risk reduction is possible in even the most complex tunnels.

Click to View Recording of Webinar

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AFTES 2017

Event Name: AFTES International Congress 2017
Dates: November 13-15, 2017
Location: Paris, France
Venue: Palais des Congrès 

The Robbins Company will be joining NFM at this year’s French Tunnelling and Underground Space Association International Congress in Paris, France. Visit our shared booth from November 13-15, to discuss current projects and innovations within the industry.

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ITA Tunneling Awards 2017

Event Name: ITA Tunneling Awards 2017
Date: November 15, 2017
Location: Paris, France
Venue: Salle Wagram

The Robbins Company is excited to announce that the recently completed Túnel Emisor Poniente (TEP) II has been nominated as an ITA Tunneling Awards finalist for Project of the Year. Winners will be announced at the ITA Tunneling Awards that will take place during the AFTES Congress in Paris, France on November 15.

The Robbins XRE TBM and its Robbins continuous conveyor system were built on location using Onsite First Time Assembly (OFTA), and featured components like a convertible cutterhead with interchangeable cutting tools, interchangeable TBM belt conveyor and screw conveyor, and multi-speed gearboxes to increase torque for tunneling through difficult ground. The 8.7 m (28.5 ft) diameter Robbins Crossover TBM bored a 5.8 km (3.6 mi) long wastewater tunnel, setting two national records in the process. The completed project will prevent flooding in urban areas and benefit the lives of 2.1 million people.

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La tuneladora que pulveriza récords en Ciudad de México realiza el cale final

El 8 de julio de 2017, un selecto grupo de autoridades responsables del proyecto, incluido el presidente de México Enrique Peña Nieto, celebró el cale final de un titánico proyecto de construcción de túneles. La TBM Crossover Robbins de 8,7 m de diámetro es la primera de este tipo de máquinas híbridas que se utiliza en Norteamérica y puso el broche final al Túnel Emisor Poniente (TEP) II. La tuneladora, del tipo denominado XRE —un cruce o crossover (X) entre TBM para roca (R) y EPB (E)— logró sortear zonas de fallas, terrenos variables y bajas coberturas, entre otros obstáculos, para lograr un récord nacional de 57 m en un día, así como avances máximos de 231 m en una semana y 702 m en un mes.

«La XRE presenta la gran ventaja de estar diseñada para trabajar en modo abierto o cerrado (EPB), lo cual le permite excavar túneles tanto en suelo como en roca. Hemos comprobado que su rendimiento ha sido muy eficiente», afirmó el ingeniero Juan Alberto Herrera Moro y Castillo, responsable en el TEPII de la Conagua, la Comisión Nacional del Agua, propietaria del proyecto.

Se empleó el método de montaje in situ OFTA para ensamblar en la misma obra esta singular máquina y su sistema de cinta transportadora Robbins, que fueron diseñados para un consorcio contratista formado por Aldesem, Proacón y Recsa. La TBM XRE Robbins incorporaba componentes tales como una cabeza de corte convertible con herramientas de corte intercambiables, transportador de cinta y de tornillo intercambiables y reductoras de velocidad variable para aumentar el par con el fin de perforar túneles en terrenos difíciles. «Las ventajas del diseño residen en su excepcional potencia de empuje y en lo sencillo que resulta variar el par de la cabeza de corte, lo cual facilita mucho el proceso en el caso de que la máquina se quede atascada en un terreno dificultoso», comentó Alberto Martínez, jefe del departamento de construcción de túneles de Recsa.

La tuneladora XRE entró en servicio en agosto de 2015 para perforar el túnel de aguas residuales de 5,8 km de longitud. La máquina estaba configurada para roca dura y montaba cortadores de disco de 20 pulgadas (51 cm) de diámetro. A principios de 2016, la TBM la primera de varias zonas de contacto, una falla de 30 m de anchura de roca fracturada y en bloques. Si bien la excavación se ralentizó al atravesar la zona de contacto, el ritmo de avance se recobró en la roca andesítica, que presentaba una mayor competencia. Tras llevar a cabo un cale intermedio en marzo de 2016 para desembocar en un pozo de 80 metros de profundidad, seguido de un proceso de inspección y mantenimiento, la TBM siguió adelante.

En otoño de 2016, mientras excavaba en roca andesítica fracturada, la TBM se encontró con una caverna natural que, presumiblemente, se había originado por un desprendimiento de rocas en una zona de transición o por un lago subterráneo que había erosionado el material rocoso. La caverna tenía un tamaño estimado de 90 metros cúbicos e incluía una zona de suelo inestable de 57 metros cúbicos. Se detuvo la tuneladora y se adoptaron medidas inmediatas para estabilizar el terreno situado frente a la máquina con espuma de poliuretano antes de rellenar la caverna con una mezcla de gravilla y lechada.

A finales de octubre de 2016, la tuneladora alcanzó un trecho final de 900 m de longitud en terreno blando, donde se pasó al modo EPB. En este último tramo de túnel con baja cobertura, la distancia desde la parte superior del túnel a los cimientos de las viviendas llegaba a reducirse hasta los 4 m y el terreno presentaba la consistencia de un suelo reconsolidado. Para estabilizar los suelos blandos y minimizar el riesgo de que se produjera un asentamiento bajo la zona residencial, el personal de construcción de túnel perforó desde la superficie e instaló 890 micropilotes a intervalos de 1 m. «Fuimos capaces de lograrlo sin causar daños en las propiedades de los vecinos de las zonas aledañas al trazado del TEPII, ni en la carretera, ni en las infraestructuras urbanas instaladas en dicha zona», explicó el ingeniero Francisco Miguel López, jefe de obra en el TEPII del contratista Aldesa.

Con las excavaciones ya concluidas, se procederá a aplicar en el túnel un segundo revestimiento de hormigón con un espesor de 35 cm antes de que entre en servicio. El túnel de aguas residuales servirá para modernizar la actual infraestructura en zonas del extrarradio situadas al oeste de la Ciudad de México y para evitar las periódicas inundaciones en Valle Dorado. El túnel beneficiará especialmente a las ciudades de Cuautitlán Izcalli, Tlalnepantla y Atizapán de Zaragoza, que en conjunto albergan a 2,1 millones de habitantes.

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Cutting Edge 2017

Event Name: Cutting Edge Conference
Dates: November 13-15, 2017
Location: Seattle, WA, USA
Venue: Renaissance Seattle Hotel 

Join The Robbins Company at the Sixth Annual Cutting Edge Conference: Advances in Tunneling Technology November 13-15, in Seattle, WA. Visit our booth to learn more about current techniques being used on Robbins projects throughout the world.

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STUVA 2017

Event Name: STUVA Expo and Conference 
Dates: December 6-7, 2017
Location: Messe Stuttgart, Germany
Venue: Messe Stuttgart Trade Fair Centre

With an increasing rate of growth, STUVA-Expo will take place parallel to STUVA-Conference December 6-7 in Messe Stuttgart, Germany. The Robbins Company is looking forward to sharing information about current TBM projects operating world-wide at this ever-growing event.

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EPB Excavation of Less Than Five Meters Below the Historic Structure of Chandpole Gate on the Jaipur Metro Project

The tunnels excavated by Continental Engineering Corporation (CEC) for the underground section of the Jaipur Metro project faced the usual challenges posed by metro projects worldwide, including small site footprints, and the associated problems regarding segment and muck storage space, etc. These challenges were, however, relatively straightforward when compared to the challenges faced by the tunneling operations. The Earth Pressure Balance (EPB) TBMs were required to bore under extremely low overburden, alongside and beneath several culturally sensitive historic structures. The age of these structures and their construction methods/materials were of great concern when considering the possible consequences of tunneling-induced ground settlement and vibrations. This paper will describe the measures taken regarding TBM operations and surface monitoring to ensure that these historic structures suffered no adverse effects due to tunneling.

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