Page 100 - Rock Mechanics For Underground Mining

ROCK MASS STRUCTURE AND CHARACTERISATION

Figure 3.30 Geological Strength In-
dex (GSI) for jointed rock masses
(after Hoek, 2003).

and Hoek (2000) present a series of indicative charts which show the most probable
ranges of GSI values for rock masses of several generic rock types.

Problems

1 A scanline survey is to be carried out on the vertical wall of an exploration drive.
The rock mass contains two sets of parallel discontinuities whose traces on the wall
◦
are mutually inclined at 75 as shown in the diagram. The traces of set A make an
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