Tunnel Boring Machine
The tunnel boring machine (TBM) is a machine used in civil engineering and mining that artificially excavates a tunnel. It is made up of a rotating cutting wheel mounted on a main frame and is used to excavate a tunnel by boring through soil, rock or other obstructions. The cutting head is mounted on a frame that is connected to an extendable cylindrical shaft, which is then supported by a thrust system. This system is used to apply a force to the machine in order to move it forward. The machine also has an excavating arm which is used to move soil and debris away from the tunnel face.
TBMs are most suitable for hard rocks and difficult-to-excavate formations such as dense soils and hard rocks that cannot be excavated using traditional methods. As they are used only underground, they are not affected by weather conditions, and they are particularly useful for creating tunnels in places where access is limited, such as mountain ranges.
There are several types of TBMs; one is a drill-and-blast machine, which uses explosives to create a tunnel through the rock. This method is mainly used for short tunnels, as the vibration caused by the explosives can cause damage to nearby structures and the environment in general. Another type is the earth pressure balancing TBM, which uses a syringe-like device to inject a slurry into the rock face. This slurry then hardens and forms a wall in front of the machine, which is then forced open as the machine moves forward.
TBMs are usually driven by hydraulic motors, usually located at the rear of the machine. How they are powered depends on their type; some are powered by compressed air or by electricity. The machine also requires a dedicated power supply, typically provided by electricity.
The speed of the TBM is usually determined by the size of its cutting wheel, but can also be controlled by its operators. The typical speed of a TBM is around 1 – 2 m per minute, or around 40-90 m per hour.
Tunnels created by TBM machines can be up to several kilometers in length, depending on the terrain and the size of the machine. As a result of the fast speed of the machine and the accuracy of the tunnels created, the use of a tunnel boring machine is becoming more common when creating tunnels.
