Modern Mining October 2019

the slope. The mesh transfers the stresses from the falling rocks to the crest cable. The cable then in turn transfers the stresses to the anchors, where they are ultimately absorbed by the in-situ material. The other area called for the installation of a rockfall barrier kit in order to intercept rocks before reaching the ramp where there are vehicles (includ- ing heavy machines) and employees moving while conducting the daily mining activities. The rock engi- neering department of Foskor performed a rockfall trajectory analysis and determined that a 500 kJ bar- rier of 3 m height would be sufficient to intercept the blocks expected to come down the slope should an incident occur. Maccaferri SA proposed the use of a RMC050 ICAT/2 Plus barrier which the mine deemed suitable for this application. Both rockfall protection systems that were installed are classified as passive systems. Passive systems permit loose rocks and other debris falling down the slope to be intercepted and contained. As the purpose of these structures is to control superfi- cial instability by catching and stopping falling rocks, their design must consider global rock sizes; the level of energy to be absorbed; and the most suit- able location on the slope. Passive systems are regularly maintained by removing loose rock caught in the system and repairing as required. Steelgrid® HR system The Steelgrid® HR system is an innovative complete system for rockfall mitigation and slope consolida- tion works. It combines a patented high strength steel wire mesh geocomposite used in conjunction

by Maccaferri SA using its rockfall design software, MACRO Studio. This was done to obtain the strength requirements of the mesh and to dimension the anchors and cables needed to implement the sim- ple drapery solution. Steelgrid® HR 50 was proposed to the mine and was deemed to have satisfactory strength properties to contain debris that might detach from the face and safely guide it to the toe of

Completed simple drapery system using Steelgrid HR 50.

October 2019  MODERN MINING  27