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Rock Mechanics.pdf - Mining and Blasting

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Figure 11.9 Ground reaction curves<br />

calculated for several points along a<br />

production drift in the Premier Mine,<br />

South Africa (after Leach et al., 2000).<br />

Figure 11.10 Use of cable dowel<br />

pre-reinforcement in cut-<strong>and</strong>-fill<br />

mining.<br />

ROCK SUPPORT AND REINFORCEMENT<br />

The pre-reinforcement of hangingwalls is also important in the now more widely<br />

used sublevel <strong>and</strong> longhole open stoping methods of mining. If practicable, more<br />

uniform coverage of the hangingwall than that illustrated in Figures 11.11a <strong>and</strong> b<br />

may be obtained by installing fans of cables from a nearby hangingwall drift as in<br />

the case shown in Figure 11.11c. Further examples of the pre-reinforcement of open<br />

stopes will be given in Chapter 14.<br />

In many of the early applications of fully grouted cable dowel reinforcement <strong>and</strong><br />

pre-reinforcement, the full potential of the reinforcing system was not realised. This<br />

was generally because of failure of the grout-cable bond <strong>and</strong> the consequent ineffective<br />

load transfer between the deforming rock mass <strong>and</strong> the cable. Since that time,<br />

considerable attention has been paid to tendon design <strong>and</strong> to installation, grouting<br />

<strong>and</strong> testing procedures (e.g. Matthews et al., 1986, Thompson et al., 1987, Windsor<br />

324

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