Table 2. Pre-grouting data derived from ndal et al., 2001.

An average cylinder thickness of 6m of grouted rock mass has been assumed. A grout density of 1.75 gm/cc is also assumed.

Rock type kg/m2 tunnel surface ? kg/m3 ? litres/m3
gneiss 11.0 to 16.5 1.8-2,8 1.0-1.6
granite 12.0 to 52 2.0-8.7 1.1-5.0
phyllite 26 4.3 2.5
rhomb porphyry 28 to (99) 4.7-(16.5) 2.7-(9.4)
syenite (dike) 30 to (186) 5.0-(31) 2.9-(17.7)
fracture zone 19 to 50 3.-8.3 1.8-4.7