Drill & blast road tunnel · T10.5

Analytical (browser)

Operator

Pattern, depth and overbreak changes take effect from the next round.

Alarms

Round cycle

Drilling pattern

Rock support

Vibration at the house

Model limits

  • The T10.5 profile is drawn as vertical walls with a semicircular roof of the same theoretical area (74.6 m²); the real profile is flatter.
  • The "Norwegian practice" pattern uses a contour spacing of 0.47 m and 0.75 of the Olofsson burden, fitted to published hole counts; it is not a design rule. Charges per hole follow the textbook rules, so the specific charge (about 1.8 kg/m³) is about a third below the 2.7–3.0 kg/m³ logged on three Norwegian road tunnels in 2021–24 (Gjengedal & Jakobsen 2025); the vibration estimate, which uses the designed charge per delay, is likely low for the same reason.
  • Activities run one after another; on site some overlap (for example sprayed concrete during a standstill), so advance can reach 75 m/week. Mucking (220 m³/h) and downtime (13 % of the round) are logged at the Ulvin rail tunnel; ventilation (20 min) and scaling (1.5 h) are a contractor's median estimates for T10.5; bolting and sprayed concrete use the NFF contract rates. Charging time, hole positioning and the reinforced ribs time are assumed. 101 production hours a week, the Tunnelbyggetid basis.
  • Vibration uses one published site fit (Stockholm Northern Link) and the building factors of one published Swedish risk analysis; the house and its distance are illustrative. Geology is illustrative.
Models: Holmberg cut and pull, Olofsson burden and charges (Yilmaz 2023), smooth contour (Dyno Nobel), Norwegian support classes (NFF; NGI Q-system), cycle rates (NFF Publications 14, 26, 28), scaled-distance vibration (Bahrekazemi et al. 2011) and SS 460 48 66 guide values. Method card in the methods reference.