A Tunnel Boring Machine is a highly efficient piece of excavation equipment used to bore circular cross-section tunnels through various ground conditions, including hard rock (Wikipedia, 2025).
In rock mining, TBMs operate by exerting thrust against the tunnel face, pushing a rotating cutterhead equipped with disc cutters directly into the rock. These cutters generate high stresses that cause the rock to fracture and spall, effectively breaking it into manageable chips (Itasca Software, Unknown).
The excavated material, known as spoil, is then typically transported away from the face via a screw conveyor or belt conveyor system through the machine’s body.
TBMs are particularly favored for long tunnels due to their capability for continuous excavation, high advance rates, and minimal over-excavation compared to traditional drill and blast methods, leading to smoother tunnel walls and reduced need for support (Robbins Company).
Their use offers several advantages, including faster advance rates, particularly for long tunnels, reduced ground disturbance, improved safety by eliminating explosives, and better air quality due to less dust and fumes (The Robbins Company).
How do you think a Tunnel Boring Machine handles different types of rock underground? Share your thoughts!
