We undertook a review of the likely quarry yield of armour and facing rock, based on the results of site observations and a geotechnical investigation previously carried out at the site.

Our client carried out quarry operations for armour rock and facing stone at a major iron ore mine site in the Pilbara region of Western Australia. Estimated yields were not being achieved due to unexpected ground conditions.

We were engaged to undertake a review of the likely quarry yield of armour and facing rock, based on the results of site observations and a geotechnical investigation previously carried out at the site.

Achievements

Based on site observations and a review of a previous geotechnical investigation carried out at the site we were able to:

  • Identify a number of dykes and locally variable fracture spacing that were not identified during the previous geotechncial investigation.
  • Indentify incorrect assumptions used in the estimation of quarry yield and presented in the previous geotechnical report.
  • Identify errors in the methodology used for the estimation of quarry yield.
  • More accurately assess quarry yield using revised assumptions and corrections to the original quarry yield methodology.

 

Solutions

Our input allowed for positive progress in payment negotiations for the client.

 

Key Challenges

Access to excavated faces to undertake scanline surveys to assess the structural geology of the rock mass was limited. To overcome this issue we were able to utilise overlapping scaled photography of inaccessible subvertical exposures to assess joint orientation and frequency. This information was supplemented by direct measurement of joints in accessible exposures and rock outcrop beyond the limits of the quarry.