Page 342 - Rock Mechanics For Underground Mining

ROCK SUPPORT AND REINFORCEMENT

Figure 11.9 Ground reaction curves
calculated for several points along a
production drift in the Premier Mine,
South Africa (after Leach et al., 2000).

Figure 11.10 Use of cable dowel
pre-reinforcement in cut-and-fill
mining.

The pre-reinforcement of hangingwalls is also important in the now more widely
used sublevel and longhole open stoping methods of mining. If practicable, more
uniform coverage of the hangingwall than that illustrated in Figures 11.11a and b
may be obtained by installing fans of cables from a nearby hangingwall drift as in
the case shown in Figure 11.11c. Further examples of the pre-reinforcement of open
stopes will be given in Chapter 14.
In many of the early applications of fully grouted cable dowel reinforcement and
pre-reinforcement, the full potential of the reinforcing system was not realised. This
was generally because of failure of the grout-cable bond and the consequent ineffec-
tive load transfer between the deforming rock mass and the cable. Since that time,
considerable attention has been paid to tendon design and to installation, grouting
and testing procedures (e.g. Matthews et al., 1986, Thompson et al., 1987, Windsor
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