Review of the Geological Strength Index (GSI) as an Empirical Classification and Rock Mass Property Estimation Tool: Origination, Modifications, Applications, and Limitations

Table 1

Empirical methods for rock mass classification and design of engineering structures in rock mass.

S. no	Empirical method	Year	Applications	Authors	Reference
1	Rock load	1946	Tunnels with steel support	Terzaghi	[15]
2	Stand-up time	1958	Tunneling	Lauffer	[16]
3	Rock quality designation (RQD)	1963, 1966	Tunneling	Deere and Miller	[17, 18]
4	Rock structure rating (RSR)	1972	Tunneling	Wickham et al.	[19]
5	Rock mass rating (RMR)	1973 (modifications 1989)	Tunnels, mines, slopes	Bieniawski	[20, 21]
6	Tunneling quality index (Q)	1974 (last modification 2002)	Tunnels, mines, foundations	Barton et al.	[22]
7	New Austrian tunneling method (NATM)	1974	Tunneling	Pacher and Rabcewicz	[23]
8	Size strength classification	1975	Tunneling	Franklin	[24]
9	Basic geotechnical classification (BGC)	1981	General	ISRM	[25]
10	Rock mass strength (RMS)	1982	Metal mining	Stille and Groth	[26]
11	Unified rock mass classification system (URCS)	1984	General	Williamson and Kuhn	[27]
12	Rock mass index (RMi)	1996	Tunneling	Palmström	[28]
13	Geological strength index (GSI)	1997	All underground excavations	Hoek and Kaiser	[29]
14	Rock tunneling quality index by TBM excavation (QTBM)	1999	TBM tunnels	Barton	[30]
15	Continuous rock mass rating (CRMR)	2003	General	Sen and Bahaaeldin	[31]
16	Rock mass excitability (RME)	2006	TBM tunnels	Bieniawski von Prein et al.	[32]
17	Rock mass quality rating (RMQR)	2015	General	Aydan et al.	[33]
18	Modification of the rock mass rating system (rock Bolt Supporting factor (RSF))	2017	Tunneling and underground excavations	Mohammadi and Hossaini	[34]
19	Anisotropic rock mass rating (ARMR)	2018	Tunneling and general	Saroglou et al.	[35]