Extension of RMR and Q-system in Taiwan

Table 3-1 Criteria for rating Rock Type A and B
Rock mass class of
Rock Type A
RMR range of
Rock Type A
RMR range of
Rock Type B
Rock mass class of
Rock Type B
AⅠ RMR≧81 ---- ----
AⅡ RMR80~61 RMR≧81 BⅡ
AⅢ RMR60~41 RMR80~61 BⅢ
AⅣ RMR40~21 RMR60~41 BⅣ
AⅤ RMR20~11 RMR40~21 BⅤ
AⅥ RMR≦10 RMR≦20 BⅥ
Table 3-2 Criteria for rating Rock Type C and D
Rock mass class
Cementation
Standards of rating
Geologic material composition
Rock
Type
CⅠ(C)
CⅠ(MIX)
CⅠ(S)
Fair or good cementation
(can’t be dented by the thumb)
The content of silt and clay is greater than 50%
The content of sand, silt, clay or gravel
individually isn’t greater than 50%
The content of sand is greater than 50%
C
CⅡ(C)
Poor or loose cementation
CⅡ(MIX)
(can be dented by the thumb)
The content of silt and clay is greater than 50%
The content of sand, silt, clay or gravel
individually isn’t greater than 50%
CⅡ(S)
The content of sand is greater than 50%
The content of boulders and coarse grains (grain
DⅠ(G) Extremely good cementation size greater than sieve #4) is greater than 75 %;
(boulders or gravel need to be contact with each other
knocked off by geologic hammer The content of boulders and coarse grains (grain
DⅠ(M) with great power)
size greater than sieve #4) is between 50% ~
75%; don’t contact with each other
The content of boulders and coarse grains (grain
Rock
Type
D
DⅡ(G)
DⅡ(M)
size greater than sieve #4) is greater than 75 %;
Fair or good cementation
contact with each other
(boulders or gravel need to be
knocked off by geologic hammer)
The content of boulders and coarse grains (grain
size greater than sieve #4) is between 50% ~
75%; don’t contact with each other
The content of boulders and coarse grains (grain
DⅢ(G)
DⅢ(M)
Poor or loose cementation
(boulders or gravel need to be
knocked off by hand)
size greater than sieve #4) is greater than 75 %;
contact with each other
The content of boulders and coarse grains (grain
size greater than sieve #4) is between 50% ~
75%; don’t contact with each other
Notes: 1.Because the amount of water content affects the tunnel construction of Rock Type C and D
considerably, this table must be adopted based on drainage in advance.
2.Sand layers and gravel layers possibly appear simultaneously on the excavation face. The
location of sand layers on the excavation face has a determinate influence on the stability of
tunnels, and it should be considered carefully while designing tunnel supports.
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