TBM Overview (Tunnel Boring Machine) key features and working.

TBM Overview

About Tunnel boring machine

A tunnel boring machine (TBM), also known as a "mole," is a large, specialized piece of equipment used for excavating tunnels. It is a cylindrical machine with a rotating cutting wheel at the front, called a cutter head, which is equipped with cutting tools or disc cutters. TBMs are used to create tunnels for various purposes, such as transportation systems, mining, water supply, sewage systems, and more.

Here are Seven key features and components of a typical tunnel boring machine:

1 Cutter Head: This is the front part of the TBM, which consists of a rotating cutting wheel. The cutter head is designed to excavate the soil or rock in front of the machine by applying pressure and rotating the cutting tools. The size and shape of the cutter head depend on the type of ground it will be excavating.

2 Cutting Tools: The cutter head is equipped with cutting tools, typically disc cutters, which are mounted on the face of the cutter head. These tools are designed to break and remove the soil or rock as the TBM moves forward. The number and arrangement of the cutting tools can vary depending on the ground conditions.

3 Shield: The shield is a structural component surrounding the TBM, protecting the workers and the machine from collapsing ground. It is typically made of reinforced steel and is designed to support the tunnel walls during excavation.

4 Thrust System: TBMs use a thrust system to push against the tunnel wall, enabling the machine to move forward. The thrust force is generated by hydraulic jacks or rams located at the back of the TBM. As the machine advances, additional segments of the tunnel lining are installed behind the TBM to provide support.

5 Conveyor System: A TBM includes a conveyor system to transport the excavated material, also known as spoil, out of the tunnel. The spoil is typically loaded onto a conveyor belt or into a series of cars that transport it to the surface for disposal or further processing.

6 Lining Installation: As the TBM progresses, precast concrete segments or other tunnel lining materials are installed behind the machine to support the excavated tunnel. These segments form the permanent lining of the tunnel and provide structural stability.

7 Guidance System: To ensure accurate alignment and direction, TBMs use a guidance system. This system may include laser-based or optical systems, as well as sensors that monitor the TBM's position and adjust its direction as needed.

Tunnel boring machines are highly efficient for tunnel construction, offering advantages such as reduced disturbance to the surrounding environment, increased safety for workers, and faster excavation compared to traditional methods. They have been used in numerous large-scale tunneling projects worldwide.