Modern Quarrying Q4 2018

ROCKFALL PROTECTION

Maccaferri’s Rockfall Barriers are designed to arrest and catch falling rocks and boulders before they fall onto quarry/mine infrastructure, machinery and haul-roads

Juan-Louis de Beer, Area Manager Technical Specialist: Rockfall at Maccaferri.

quarrying sector include Rockfall Drapery; Steelgrid HR Drapery Mesh (secured and simple drapery solutions); HEA Panel Netting (high-strength rope panel netting); Rockfall Barriers (static rockfall catch fences from 100 to 8 500 kJ); as well as Static Rockfall Embankments. Steelgrid HR System Maccaferri’s Steelgrid HR System – an innovative complete system for rockfall mitigation and slope consolidation works – is ideal for drapery on high walls, containing rock detachment, and provides surface stabilisation on areas prone to slippage. It combines a patented high strength steel wire mesh geo- composite which is used in conjunction with anchor plates, specific U-bolts and mesh connectors. The Steelgrid HR mesh is a composite of double twisted steel wire, hexago- nal mesh with high tensile strength steel cables, woven into the mesh during the manufacturing process. The high level corrosion protection for the steel wire mesh (Class A Galvanised), ropes (Class A Zn95%-Al5% Galvanised) and accessories make the Steelgrid HR System ideal for rockfall protection in all continental environments. Maccaferri’s manufacturing process adapts the traditional twisting process to create a ‘hybrid mesh’; the mesh features a combination of full and half-hex- agonal shaped mesh apertures. To provide high tensile strength and punching resistance at low-strain, the steel cables lie predominantly straight within the hexagonal mesh. As the mesh offers immediate resistance to loads at minimal strain, there is no requirement to pre-tension the mesh. The post-manufacturing alignment of the steel cables within Steelgrid HR can vary depending on the rope spacing and position within the roll. Performance testing is carried out in compliance with the natural variability. When the mesh is installed and loaded, the ropes lie straight within the mesh, offering high strength and stiffness (strength at low strain) in com- parison with traditional double twist and single twist meshes; elongation of Steelgrid HR is in the range of 5-7% compared with 16-23% for double twist meshes depending on mesh/wire combinations. Punch resistance, tested in accordance with UNI 11437, shows a greater improvement with average increases of 20-40% compared with double twist meshes. HEA Panel Netting Maccaferri’s HEA Panels (High Energy Absorption) are said to be the stiffest products within its Mac.RO Systems mesh range, offering extreme strength at low strain. The panels are woven from a single continuous length of high ten-

The HEA panels are woven from a single continuous length of high tensile strength steel wire rope, joined at each crossing point with the patented HEA ‘double knot’ connection. sile strength steel wire rope, joined at each crossing point with the patented HEA ‘double knot’ connection. “HEA Panels are used within rockfall protection works where high strength and puncture resistance at very low strain are required. The panel is woven from one continuous length of high tensile steel wire rope (1 770 N/mm²) and joined at the crossing points with the patented HEA ‘double knot’, to form a durable and reliable connection. An alumin- ium ferrule connects the two ends of the steel wire rope together,” explains De Beer.

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MODERN QUARRYING QUARTER 4 - 2018