Design Methods - Rock Mechanics Based on an Anisotropic Jointed Rock Model - page 345

Figure 12.12 Influence of discontinuity orientation with respect to the tunnel (Sommer 2009)

Figure 12.13 Influence of discontinuity orientation on the stability of a tunnel (Sommer 2009)

Deficiencies and limitations of classification systems have also been ascertained and
discussed in Schneider (1980), Trunk & Hönisch (1990), Pells (1997), Spaun & Thuro
(1999), Erichsen (2002), Stille & Palmström (2003), Palmström & Broch (2006), Som-
mer & Wittke (2011), Wittke & Sommer (2011) and Anagnostou & Pimentel (2012).
In Milne & Potvin (1992) and Bieniawski (1997)

the subjective aspects of classification

systems were critically reviewed.