Modern Quarrying Q4 2018

deployed towards the foot of rock walls. Barriers are designed to arrest and catch falling rocks and boulders before they fall onto quarry/mine infrastructure, machinery and haul-roads. “Our range includes barriers with certified energy absorption capacity from 100 to 8 500 kJ. Our barriers offer the lowest maximum deflection under impact, and high- est residual height in the market,” says De Beer. The most important element of the barrier is Maccaferri’s patented compression brake, or damper, which absorbs the impact energy, transferring it throughout the barrier structure. The barrier consists of the brakes, support cables and posts, barrier panels and anchors with bracing cables. When impacted, the brake is progressively crushed, and the load is evenly distributed between the posts, thereby minimising stress on all the elements of the bar- rier. When the compression brake has been triggered, there is no need to replace the entire barrier; it is only necessary to remove fallen rocks and replace the used components and compression brake. “The retaining layer is made of continuous steel cable net panels or ring net panels (depending on the energy requirements of the specific barrier). During an impact, the system ensures that the energy of the falling rock is dissipated, and the rock is prevented from moving any further. The energy dissipating devices absorb the applied energy by deformation and not by friction, thereby ensuring a better and lon- ger lasting performance,” concludes De Beer. l

The high level corrosion protection for the steel wire mesh, ropes and accessories make the Steelgrid HR System ideal for rockfall protection in all continental environments.

Panels are designed for long-term static loads. In case of a rock breakage, the whole load created by the frag- mented material is transmitted to the knot connections and evenly redistributed to the entire mesh, so that the energy is dissipated. HEA panels can be used alone or in combination with Maccaferri’s Double-Twist mesh or Steelgrid HR drapery systems. When coupled with the company’s geosynthetic mat MacMat R, HEA panels can be used with dowel rein- forcement to protect slopes from landslides and erosion. Rockfall Barriers It can sometimes be impossible to anchor drapery and HEA panels on hard-to-reach slopes, due to cost or safety issues. In this case, dynamic rockfall barriers are

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QUARTER 4 - 2018 MODERN QUARRYING