Numerical Modeling for Engineering Analysis and Designing of Optimum Support Systems for Headrace Tunnel
Table 2
Parameters for numerical modeling.
Geotechnical unit
Unit weight (g/cm3)
Modulus of elasticity (MPa)
Poisson’s ratio ()
Hoek and Brown constants
Vertical stress (MPa)
Horizontal stress (MPa)
RMR support
Q-system support
mb
s
a
GU-1
2.71
3.41e4
0.188
7.669
0.0117
0.503
19.00
5.23
Locally, 3 m long bolts in crown of 20 mm diameter and fully grouted, spacing between bolts of 2.5 m with occasionally wire mesh, shotcrete with a thickness of 50 mm where necessary, and no steel set required
2 m long systematic bolting (fully grouted with 20 mm diameter) with a spacing of 2.32 m between bolts; fiber-reinforced sprayed concrete of 50–60 mm thickness at crown
GU-2
2.76
3.42e4
0.051
1.934
0.0060
0.504
11.70
2.06
4 m long systematic bolts of 20 mm diameter and fully grouted, spacing range between bolts of 1.5–2 m in crown and walls with wire mesh in crown, shotcrete with a thickness range of between 50 mm and 100 m in crown and 30 mm in the sides of tunnel, and no steel set required
2 m long systematic bolting (fully grouted with 20 mm diameter) with a spacing of 2.5 m between bolts; fiber-reinforced sprayed concrete of 50–60 mm thickness at crown
GU-3
2.69
5e4
0.277
6.154
0.0256
0.502
11.60
3.02
Locally, 3 m long bolts in crown of 20 mm diameter and fully grouted, spacing between bolts of 2.5 m with occasionally wire mesh, shotcrete with a thickness of 50 mm where necessary, and no steel set required
2 m long systematic bolting (fully grouted with 20 mm diameter) with a spacing of 2.48 m between bolts; fiber-reinforced sprayed concrete of 50–60 mm thickness at crown
