Rock Mass Classification for Columnar Jointed Basalt: A Case Study of Baihetan Hydropower Station

Table 1

Existing rock mass classification systems.

Name	Abbrev.	Authors	Application	Comments
—	—	Ritter [28]	Tunnels	The first attempt for the formalization of an empirical approach to tunnel design.
Rock load	—	Terzaghi [29]	Tunnels	The earliest reference to the use of rock mass classification for the design of tunnel support.
Stand-up time	—	Lauffer [30]	Tunnels	Related to the stand-up time of an unsupported tunnel excavation.
Rock quality designation	RQD	Deere [31]	General	Component factor of many classification systems.
Rock structure rating	RSR	Wickham et al. [32]	Tunnels	First rating system for rock masses.
Rock tunneling quality index	Q	Barton et al. [33]	Tunnels	The most commonly used classification systems for tunnels.
Rock mass rating	RMR	Bieniawski [34]	Tunnels and cuttings	Widely used for both tunnels and slopes.
Rock mass index	RMi	Palmstrom [35]	Tunnels	An approximate value for the compressive strength.
New Austrian tunneling method	NATM	Rabcewicz [36]	Tunnels	Used in the determination of support measures.
Mining rock mass rating	MRMR	Laubscher [37]	Mines	Based on RMR (1973).
Rock mass strength	RMS	Selby [38]	Cuttings	Based on natural slope database.
Slope mass rating	SMR	Romana [39]	Cuttings	Based on RMR (1979). The most commonly used classification system for slopes.
Slope rock mass rating	SRMR	Robertson [40]	Cuttings	Based on RMR. The classification is provided for of weak altered rock mass materials from drill hole cores.
Chinese slope mass rating	CSMR	Chen [41]	Cuttings	Adjustment factors have been applied to the SMR system for the discontinuity condition and slope height.
Geological strength index	GSI	Hoek et al. [42]	General	Based on RMR (1976). For nonstructurally controlled failures.
Modified rock mass rating	M-RMR	Unal [43]	Mines	For weak, stratified, anisotropic, and clay-bearing rock masses.
Basic quality	BD	Ministry of Water Resources, PRC [44]	General	Engineering quality classification of rock mass in China.
Rock slope deterioration assessment	RDA	Nicholson and Hencher [45]	Cuttings	For shallow, weathering-related breakdown of excavated rock slopes.
Slope stability probability classification	SSPC	Hack et al. [46]	Cuttings	Probabilistic assessment of independently different failure mechanics.
Volcanic rock face safety rating	VRFSR	Singh and Connolly [47]	Cuttings (temporary excavations)	For volcanic rock slopes to determine the excavation safety on construction sites.
Falling rock hazard index	FRHI	Singh [48]	Cuttings (temporary excavations)	Developed for stable excavations to determine the degree of danger to workers.
Basic geotechnical description	BGD	ISRM [49]	General	Established in 1981 by ISRM.
Size strength classification	SSC	Franklin [50]	Tunneling	Based on the strength of intact rock and the spacing of discontinuities.
Simplified rock mass rating	SRMR	Brook and Dharmaratne [51]	General	Three major components: the intact rock strength, joint spacing, and joint type.