The speed of a Tunnel Boring Machine (TBM) — often called its advance rate — depends on many factors, such as soil or rock type, machine size, ground conditions, and project design.

   1、Typical TBM Speeds

   Record speeds (ideal conditions)：30–50 meters per day, Rare, achieved in uniform soft ground

   Soft soil (clay, sand, silt)：10–20 meters per day, Faster due to easier cutting and less wear

   Mixed ground (soil + rock)：5–15 meters per day, Moderate pace; frequent tool changes

   Hard rock (granite, basalt)：2–10 meters per day, Slowest; high cutter wear and heat

   2、Factors Affecting TBM Speed

   ① Geological conditions:Softer, more uniform materials allow for higher speeds. Hard or fractured rock slows progress.

   ② TBM type:

   · EPB (Earth Pressure Balance) → for soft ground, higher speeds possible.

   · Slurry TBM → used in water-bearing soils, slower due to slurry processing.

   · Hard rock TBM → robust but slower due to cutting resistance.

   3、 Example Projects

   ①  London Crossrail (UK): ~15–25 m/day average.

   ②  Gotthard Base Tunnel (Switzerland): ~8–12 m/day through hard rock.

   ③  Shanghai Metro (China): up to 25–35 m/day in soft clay.

   4. Advantages Over Traditional Methods

   ① Precision: Maintains high axis alignment accuracy, crucial for segment lining.

   ② Safety: Shield machines prevent soil collapse; closed systems manage groundwater ingress.

   ③ Speed: Continuous excavation reduces project timelines versus drill-and-blast methods.

   In general, a modern TBM advances at 5 to 25 meters per day, with the potential for much faster rates in favorable conditions.