Tunnel boring machine

A big machine digs long tunnels.

It can go through hard rock. It can go through wet sand too. This helps us make roads under the ground.

The machine makes the walls very smooth. This makes it easy to line the tunnel. Some machines are even called moles. They can dig many meters every week. It is a very strong tool.

A tunnel boring machine, or TBM, is a big tool used to dig tunnels.

Some people call these machines a "mole" or a "worm." They can dig through hard rock, sand, or wet soil.

These machines make very smooth tunnel walls. This helps keep the ground around the tunnel still. It also makes it easier to line the tunnel walls.

In the 1800s, people made early versions of these tools. One early machine used many drills on a locomotive. Another used metal wheels to break up rock.

These machines helped build tunnels for trains and water.

Today, TBMs are very large and powerful. Some machines can dig over 700 meters of rock in one week.

A machine named Bertha was one of the largest ever built. It helped make a tunnel in Seattle. Another big machine named Martina helped dig a tunnel in Italy. These machines are expensive to make and move. However, they are very useful for long tunnels.

A tunnel boring machine, or TBM, is a huge tool used to dig tunnels.

People sometimes call these machines a "mole" or a "worm." They are used to excavate through hard rock, sand, or wet soil.

TBMs are better than old methods like drilling and blasting. They make very smooth walls inside the tunnel. This helps keep the ground around the tunnel still. It also makes it easier to line the tunnel walls.

These machines work by cutting through the earth in a steady way. Many TBMs use a rotating head to break the ground. Some use metal wheels to apply high pressure to the rock.

Others use many drills or hammers on a rotating part. Some machines even look like giant hole saws. The machine moves forward as it removes the dirt or rock. This allows workers to build paths through mountains or under cities. Large machines can dig through rock at speeds over 700 meters per week. Soil machines can also move over 200 meters per week.

Inventors have worked on these machines for a long time. In 1825, Sir Marc Isambard Brunel made a cutting shield. This was a new idea for protecting workers. In 1846, Henri Maus built a machine for a tunnel in the Alps. It had more than 100 drills on a machine the size of a locomotive.

In 1853, Charles Wilson made a machine for the Hoosac Tunnel in the United States. His machine used cutting discs to break the rock. Later, Major Thomas English used a machine to dig through chalk. His machine traveled 1,840 meters between 1882 and 1883.

Many famous machines have been built since then. In Canada, a machine named "Big Becky" helped build a tunnel under Niagara Falls. In 2013, a massive machine named Bertha was sent to Seattle, Washington. Bertha was one of the largest machines ever made.

It finished its job on April 4, 2017. Another huge machine named Martina was used in Italy in 2013. Martina weighed 4,500 tons and was used for the Variante di Valico project. It used a lot of energy to dig through the ground.

Modern TBMs help us connect places in ways we never could before. They allow us to build subway lines under busy cities. They also help us build long rail tunnels under the sea. Even though these machines are expensive to build, they are worth it for long paths. They make the hard job of digging much faster and safer. We can see their work in the roads and rails we use every day. The world is full of hidden paths made by these giant machines.

A tunnel boring machine (TBM) is a specialized piece of heavy equipment used to excavate tunnels. These machines are often called "moles" or "worms" because of how they move through the earth. TBMs provide a modern alternative to older methods like "hand mining" or the process of drilling and blasting. They are designed to dig through various materials, including hard rock, sand, and both wet or dry soil.

Using a TBM allows for much more rapid excavation than traditional techniques. They also produce very smooth tunnel walls. This smoothness reduces the cost of lining the tunnel with permanent materials. Because they limit the disturbance to the surrounding ground, they are ideal for tunneling in busy urban areas.

The mechanism of a TBM depends on the specific technology used for the ground type. Most machines use a rotating cutter head to break apart the earth. Some designs utilize simple metal wheels to apply high pressure, which fractures the rock. Other machines use rotating arrays of drills or hammers to chip away at the surface. Some TBMs are even designed to look like giant hole saws.

As the machine cuts, it moves forward through the material. The speed of this process varies based on what is being dug. In the 21st century, TBMs excavating through rock can reach speeds of over 700 meters per week. Machines designed for soil can exceed speeds of 200 meters per week. However, tunneling speeds generally decline as the size of the tunnel increases.

Different types of TBMs are engineered for specific environments. Specialized technologies are required depending on whether the machine is facing hard rock or soft soil. Some machines use an "earth pressure balance" method to manage the ground. For example, the machine named Bertha was reported to be a very large earth pressure balance machine.

Other machines are designed specifically for mining, such as those used in potash or coal. In 1916, the "Eisener Bergmann" was developed for potash mines in Germany. It used a large rotating roller fitted with cutters. In the United States, the "McKinlay Entry Driver" was invented in 1918 for coal mines. This machine used metal tines mounted on two side-by-side rotating arms.

The history of tunneling technology began with the concept of the cutting shield. Sir Marc Isambard Brunel developed the first successful tunneling shield in 1825 for the Thames Tunnel. While this was a major invention, it was not yet a complete boring machine. The digging still relied on standard excavation methods of that time. In 1846, Henri Maus built the "Mountain Slicer" to dig the Fréjus Rail Tunnel through the Alps. This machine was the size of a locomotive and used over 100 percussion drills.

However, political revolutions in 1848 affected its funding. The tunnel was eventually finished ten years later using less innovative pneumatic drills.

In the United States, Charles Wilson built a machine for the Hoosac Tunnel in 1853. Known as "Wilson's Patented Stone-Cutting Machine," it was made of cast iron. This machine was important because it used cutting discs attached to a rotating head. This design anticipated many features of modern TBMs.

Later, in the 1870s, John D. Brunton built a machine using cutting discs mounted on rotating plates. These plates were mounted eccentrically so the discs could cover almost the entire rock face. Major Frederick Edward Beaumont and Major Thomas English also made significant improvements to boring machines in the late 1800s. These advancements helped machines travel much longer distances.

One notable historical attempt at cross-channel tunneling occurred in the late 1800s. In 1875, the French National Assembly approved a tunnel under the English Channel. Major Thomas English used his TBM to tunnel through chalk between 1882 and 1883. The machine traveled a total of 1,840 meters. A French engineer, Alexandre Lavalley, used a similar machine to drill 1,669 meters from the French side.

Despite this technical success, the project was abandoned in 1883. The British military feared the tunnel could be used as an invasion route. Later, the same TBM was used to bore a railway ventilation tunnel under the Mersey River.

Modern TBMs are massive feats of engineering with incredible scale. The machine named Martina, used for the Variante di Valico project in Italy, is a prime example. Martina was built by Herrenknecht AG and is one of the largest hard rock machines. It has an excavation diameter of 14.6 meters and a total weight of 4,500 tons.

The machine has a total installed capacity of 18 MW and consumes about 62 GWh of energy every year. Another massive machine, Bertha, was delivered to Seattle in 2013 for the Highway 99 tunnel project. Bertha had a bore diameter of 17.5 meters and completed its work on April 4, 2017. These machines allow us to build the massive infrastructure, like subways and hydroelectric tunnels, that modern society requires.