Previous fundamental research projects have indicated the value of continuous closure measurements in deep tabular excavations for improved support design, hazard assessment and for quantifying the effect of seismicity on stope closure. This paper describes further measurements in a VCR stope to validate some of the earlier findings. Calculation of the closure ratio showed that it is a good measure to identify different ground conditions and possible hazards. This work was supported by numerical modelling results, which showed that the closure ratio is very useful in discriminating the response of different geotechnical environments.

Des projets precedents de recherche fondamentale ont demontre la valeur de mesures continues de fermeture dans le cas de profondes excavations tabulaires pour une conception amelioree du soutien, de l'evaluation du danger et pour quantifier l'effet de la seismicite sur l'affaissement du toit d'un chantier d'abattage. Le present document decrit d'autres mesures dans un chantier d'abattage VCR afin de valider certaines des conclusions precedemment formulees. Le calcul du degre d'affaissement montre qu'il y va de soi d'identifier differentes conditions de sol ainsi que les dangers possibles. Les presents travaux ont ete confirmes par des resultats de modelisation numerique, lesquels ont demontre que le taux d'affaissement est très utile quant à discerner la reponse dans des environnements geotechniques differents.

Vorherige Forschungsprojekte haben den Wert von kontinuierlichen Setzungsmessungen im tiefen Sudafrikanischen Strebabbau angedeutet, vor allem fur Ausbaudesign und Risikobewertung, als auch fur die quantitative Bestimmungen der seismizitatsabhangigen Setzung. Dieses Referat beschreibt weitere Messungen in einer VCR Grube um fruhere Bestimmungen zu bewerten. Dass errechnete Konvergenzverhaltniss erweiste sich als eine gute Massnahme zur bestimmung von geotechnischen Zonen und moglichen Risiken. Numerische Analyse unterstutzte die vorliegende Arbeit und deutete darauf, dass das Konvergenzverhaltniss sehr brauchbar ist um Verhaltensunterschiede der geotechnischen Zonen zu erproben


Work in the SIMRAC projects GAP332 and GAP601b indicated that continuous stope closure measurements in deep tabular excavations of the South African gold mining industry might be a very valuable diagnostic tool in the interpretation of rock mass behaviour. Especially in the areas of hangingwall stability, the risk of falls of ground and effective support design, little information can be obtained from existing seismic systems. Much can be gained from a systematic programme of closure measurements to complement the seismic data. Some specific examples where continuous stope closure measurements are useful include:

  • Identification of different geotechnical areas (Malan and Napier, 1999)

  • Identification of areas with high face stresses and are therefore prone to face bursting (Malan, 1999a)

  • Identification of areas with a large rock mass mobility leading to unstable hangingwall conditions (Malan, 1999a)

  • Estimation of closure rates at different mining rates needed for effective support design (Malan, 1999b)

  • To assess the effectiveness of preconditioning (Malan, 1999a)

  • To assess the effect of seismicity on stope closure (Malan, 1998)

From these studies, the concept of a continuous real-time mine-wide closure system was born as it was felt that the design parameters and hazard identification tools available.

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