Hard-rock TBM

Analytical (browser)

Operator

Alarms

Cutting

Cycle

Rock and support

Advance with downtime

Model limits

  • Geology along the drive is illustrative; rock strengths, CAI and RMR are typical values for the rock types, not a project.
  • Penetration from the CSM model, with ψ fitted to the Follo Line TBM1 mean. Over 18 Follo sections it was within about ±27 % (the band shown) using mean rock strength, but 0.4–2.9× using one strength test per section; other rock types are untested.
  • Downtime per km follows Farrokh (2018). Support downtime is digitised from a figure (±20 h/km). Cutter wear excludes chipping and bearing failures.
  • Ground response: 300 m of cover, GSI = RMR − 5, typical mi and intact modulus. Closure from the closed-form ground reaction curve (no dilation, severe in very weak rock); squeezing class from Hoek & Marinos. Shield friction is a screening estimate that can under-predict by up to about 2×; the gripper bearing check is our own simple comparison with rock-mass strength.
    Models: CSM disc cutters with drive and speed limits (Rostami & Ozdemir; Rostami & Chang 2017), cutter wear (Frenzel 2011), RMR support classes (Bieniawski 1989), downtime per km (Farrokh 2018). Machine layouts from the methods reference.