Table 10 Relationship between in-situ excavation classes and GSI, basic RMR89, and Q values.
From: Re-evaluation of excavation class limits for underground excavations based on new data
Parameters | Limits | Excavation class | Descriptions |
|---|---|---|---|
GSI | > 55 | Blasting | Good-very good / Blocky-massive |
40–55 | Hammer&Blasting | Fair-poor / Blocky-very blocky | |
30–40 | Hammer | Poor / very blocky | |
< 30 | Digging | Poor-very poor / blocky disturbed seamy (a) | |
Basic RMR89 | > 55 | Blasting | Good-very good (occasionally fair) |
40–55 | Hammer&Blasting | Fair | |
< 40 | Hammer or Digging | Poor-very poor (b) | |
Q | > 1 | Blasting or Hammer&Blasting | Poor-fair-good |
0.2-1 | Hammer | Very poor | |
< 0.2 | Digging | Extremely poor-exceptionally poor (c) |
