TBM machine
TBM Machine (Tunnel Boring Machine) 🚇
A TBM (Tunnel Boring Machine) is a massive machine used to excavate tunnels through soil, rock, and other underground materials. It is commonly used to build metro railways, road tunnels, water tunnels, and underground railway systems.
How does a TBM work?
- Cutting the ground
A large rotating cutterhead breaks and cuts through soil or rock.
- Removing excavated material
Conveyor belts or other systems transport the soil and broken rock out of the tunnel.
- Building tunnel walls
Many TBMs install precast concrete segments to form a strong, protective tunnel lining as they advance.
Main parts of a TBM
- Cutterhead: Cuts through rock and soil.
- Shield: Protects workers and machinery inside the tunnel.
- Hydraulic jacks: Push the machine forward.
- Conveyor system: Carries excavated material away.
- Control room: Monitors and controls the machine.
- Lining system: Installs tunnel-supporting segments.
Types of TBM machines
- Hard Rock TBM
Designed to bore through hard rock in mountains and underground passages.
- Earth Pressure Balance (EPB) TBM
Commonly used in cities for metro tunnels and soft ground, helping control ground pressure.
- Slurry TBM
Uses pressurized slurry to support the excavation face, particularly in water-bearing and unstable ground.
Interesting facts about TBMs
- A TBM can be longer than 100 metres, depending on its design and supporting equipment.
- Some machines have cutterheads more than 15 metres in diameter.
- Large TBMs can cost tens or hundreds of millions of dollars.
- TBMs are useful for constructing tunnels with less surface disruption than many conventional excavation methods.
In Nepal 🇳🇵, TBMs can be useful for hydropower water tunnels, road tunnels, and other underground infrastructure, especially in mountainous terrain.