What machine is used to build tunnels? There isn't just one machine, but a whole family of specialized machines used to build tunnels, chosen based on the geology (rock or soft ground), the tunnel's purpose, and its size.

   Here’s an overview of it and other common machines involved in tunnel construction:

   1. Tunnel Boring Machine (TBM)

   ①  Function: The TBM excavates tunnels through soil or rock by cutting through the ground with a rotating cutter head.

   ②  Structure: It has a large circular front shield, cutter discs or blades, a conveyor system to remove muck (excavated material), and a segment erector to install concrete tunnel linings.

   ③  Advantages:

   Fast and continuous excavation

   Safe and stable (supports tunnel walls during digging)

   Produces smooth tunnel walls suitable for transportation or utility use

   Used for: Subway tunnels, railway tunnels, highway tunnels, and underground utilities.

   2. roadheader

   ①  Function: A machine with a rotating cutting head on a boom, used for soft to medium-hard rock.

   ②  Advantages: Flexible and can cut in various shapes or directions.

   ③  Used for: Short tunnels, mining, or when geological conditions change frequently.

   3. drilling and blasting Equipment

   ①  Function: Involves drilling holes into rock, placing explosives, blasting, and removing debris.

   ②  Advantages: Effective for hard rock and mountain tunnels.

   ③  Used for: Mountain road tunnels, hydropower tunnels, and mines.

   4. mucking Loader / Mucking Machine

   ①  Function: Loads and removes blasted or excavated material from the tunnel.

   ②  Used for: Both TBM and drill-and-blast methods.

   5. shotcrete machine (Spray Concrete Machine)

   Function: Sprays concrete onto tunnel walls to stabilize them during or after excavation.

   In reality, a single large tunnel project might use a combination of these methods. For example, the main tunnels might be dug with a TBM, while the connecting cross-passages are built using roadheaders or drill and blast.

   In summary:

   Modern large tunnels: Use TBMs

   Smaller or irregular tunnels: Use roadheaders or drill and blast methods