Page 584 - Rock Mechanics For Underground Mining

MONITORING ROCK MASS PERFORMANCE

Figure 18.16 (Cont.)

increased progressively until the event of 28 June 2001 when there was a sudden
increase in displacement indicating cable rupture. Monitoring showed that cable dis-
placements and loads decreased to the east and west of this location. The SMART
cables responded to a majority of the events recorded in the area over this period.
For events of magnitude 1.6 to 1.7 Mn, the cables showed no load increase. For
events of up to 2.2 Mn, minimal load increases were measured but no immediate
rehabilitation was required. For events of greater than 3.0 Mn, direct load increases
of up to 20 tonnes per twin strand cable were measured. In these cases, the cables
were replaced in the affected areas. The combined seismic and SMART monitoring
program permitted immediate assessments to be made of the degree and extent of
damage resulting from the more recent seismic events. It allowed the exact location
and the amount of reinforcement capacity consumed to be defined for each seismic
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