Martina Tunnel Boring Machine Types and Uses

The Martina tunnel boring machine is a versatile tool that comes in various types. The Earth Pressure Balance (EPB) machine is one of the most common types used for urban tunnel projects.

EPB machines are designed to handle complex geological conditions and can excavate through a wide range of soil types. This makes them ideal for projects with uncertain or changing soil conditions.

The EPB machine's ability to handle complex conditions is due to its ability to control the earth pressure around the tunnel face. This is achieved through a balance of earth pressure and vacuum pressure, which allows the machine to maintain a stable tunnel face.

Martina's EPB machine has a diameter of 6.4 meters and a cutterhead speed of 4.3 meters per minute.

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Martina, the tunnel boring machine, is a remarkable piece of engineering. It typically consists of a rotating cutting wheel in front, called a cutter head, followed by a main bearing, a thrust system, a system to remove excavated material (muck), and support mechanisms.

These machines vary greatly depending on site geology, amount of groundwater present, and other factors. The type of terrain being excavated plays a huge role in determining the type of tunnel-boring machine used.

There are primarily three types of tunnel-boring machines: tunneling machines, shields, and double-shield machines. Tunneling machines are designed to excavate hard or semi-hard rocks without the need for a support system.

Shields, on the other hand, are designed for terrain that requires installing support systems. They have an outer metal chassis that temporarily holds the ground and is positioned from the front to facilitate the assembly of the final shoring that ensures the tunnel's stability.

Here's a brief overview of the main types of shields:

Double-shield machines can work like a tunneling machine or a shield, depending on the quality of the rocky terrain. This alternative is ideal for stretches of terrain that vary between soil and rock.

Tunnel Construction is a complex process that involves careful planning and execution.

A tunnel-boring machine like Martina performs the excavation process with its rotating head, making a hole in the ground using a motor with a hydraulic or electric system.

The machine's pushing force is a result of the action of perimeter jacks supported on rings, which are pushed against the tunnel wall by other jacks, giving the machine enough strength and grip.

The tunnel-boring machine is equipped with cutting elements that can have different shapes and be made of different materials, depending on the tunnel's characteristics.

Tunnel size can vary greatly, ranging from 1 to 17 meters in diameter.

The smallest tunnels are constructed using micro tunnel shield TBMs, which bore tunnels of 1 to 1.5 meters in diameter.

A tunnel-boring machine's cutting head rotates to make a hole in the ground using a motor with a hydraulic or electric system.

The machine's pushing force comes from perimeter jacks supported on rings that are pushed against the tunnel wall by other jacks.

The cutting elements on the machine can have different shapes and be made of different materials, depending on the tunnel's characteristics.

Behind the machine is a platform on rails called "lagging equipment" or "buck-up", where fans, transformers, and a belt to remove excavated material are located.

The tunnel-boring machine's rotary head continues drilling due to the machine's strength and grip provided by the perimeter jacks and rings.

After excavation, the machine stops, and prefabricated, reinforced concrete called voussoirs are used to install rings in the tunnel structure for stability.

Marta, the tunnel boring machine, has returned home after completing its operations in Lonato.

The machine, named Martina, was originally deployed in Lonato in October 2020 and arrived at the end of the first tunnel section in September 2020.

After a two-year gap, Martina was reassembled and resumed work on the second tunnel section, which was finally completed on February 21.

The tunnel, part of the 7.95 km long "Sistema Lonato" project, will have trincee in entrance and exit, and artificial galleries at both ends.

The machine will be returned to its Chinese manufacturer, China Railway Engineering Group, as per the contract.

Behind Martina, the tunnel boring machine, is a backup system that plays a crucial role in the tunneling process. This system includes a trailing support deck with mechanisms for muck removal, slurry pipelines, control rooms, and electrical systems.

Conveyors and other systems for muck removal are a key part of the backup system, allowing for efficient removal of debris and soil. Dust-removal and ventilation systems are also essential components, ensuring a safe working environment for the crew.

The backup system also includes electrical systems, which power the various mechanisms and equipment. Control rooms are another important feature, providing a central location for monitoring and controlling the tunneling process.

Mechanisms for transporting pre-cast segments are also part of the backup system, enabling the crew to move these large segments into place.

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Martina, our trusty tunnel boring machine, is just one of the many methods used for excavating tunnels. Tunnel boring machines like Martina are designed to excavate hard or semi-hard rocks without the need for a support system.

But what about other methods? Wall chasers, for instance, are used for civil engineering and construction projects with excavation lengths of no more than 2 kilometers. They're also used to tear off pieces of ground with low and medium resistance.

In contrast, tunnel boring machines like Martina can execute projects of greater length and are suitable for high-strength terrain. Here's a comparison of tunnel boring machines and wall chasers:

Tunnel-boring machines and wall chasers are two distinct methods of mechanically excavating tunnels. They share the common goal of excavation, but differ in their design and functionality.

A tunnel-boring machine typically has a rotating head, whereas a wall chaser has an articulated arm with friction spikes and moves on belts. This design difference allows wall chasers to effectively tear off pieces of ground with low and medium resistance.

Tunnel-boring machines, on the other hand, are capable of handling high-strength terrain, making them a more versatile option for various projects. In contrast, wall chasers are generally used for civil engineering and construction projects with excavation lengths of no more than 2 kilometers.

Here's a comparison of the two methods:

Tunnel-boring machines are ideal for projects that require excavating long lengths of high-strength terrain, while wall chasers are suited for shorter projects with low to medium resistance ground.

A tunnel boring machine, or TBM, is a machine that can excavate tunnels in a single operation, called full-face drilling. It has a rotating head with cutting parts and runs on 100% electric power.

TBMs are designed to work in a variety of terrain, including hard or semi-hard rocks and soft rock soils. There are different types of TBMs, including tunneling machines and shields.

Tunneling machines are designed to excavate hard or semi-hard rocks without the need for a support system. Shields, on the other hand, are designed to excavate in terrain that requires installing support systems.

Some shields have an outer metal chassis that temporarily holds the ground, while others have a pressurized closure with contained air or are earth pressure balance shields (EPB).

TBM, or Tunnel Boring Machine, is often compared to other excavation methods, but its reputation as a rival to other techniques is well-deserved.

In Italy, the Guinness TBM was used for the excavation of the M4 metro line in Milan, completing a 1.6 km tunnel in just 16 months.

The TBM's ability to work in complex geology and tight spaces is unmatched, as seen in the case of the Gotthard Base Tunnel in Switzerland, where it excavated a 57 km tunnel through challenging rock conditions.

The TBM's high speed and efficiency make it an attractive option for long-distance tunnel projects, such as the Brenner Base Tunnel in Italy, which will stretch 55 km when completed.

However, the TBM's high upfront costs and limited versatility can make it less suitable for smaller or more complex projects.