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• Kenny Casilla

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rock reinforcement

Atlas Copco rock bolts for mining Modern computer-based geotechnical monitoring techniques indicate that the greatest relaxation or movement of the rock mass occurs immediately following excavation. They confirm that, after a certain period, the rock will establish a new equilibrium based on its own inherent self-supporting capacity. The best quality rock will remain self-supporting for extensive periods of time without the need for extra support. As the rock quality declines, support requirements increase proportionally. The poorer the quality of the rock, the greater the degree of support required, and it becomes increasingly

crucial to install reinforcement as quickly and as close to the face as possible after excavation. Engineers involved in the design of rock reinforcement systems must satisfy ever increasing demands to optimize the design to gain maximum safety and economy. The primary objective in the design of the support system is to assist the rock mass to support itself. Accordingly, quality and time are the two main parameters which must be taken into account when determining the type of rockbolt to be used for rock reinforcement, in both mining and construction applications.

Swellex The Swellex concept entails that the rock is secured by immediate and full support action from the Swellex bolts. The moment the Swellex bolt is expanded in the hole, it interacts with the rock to maintain its integrity. The quality of the bolt installation is automatically confirmed when the pump stops, and is independent of rock mass conditions or operator experience. Controllability means safety! The Swellex rockbolts are designed to optimize the effectiveness of each bolt, so the bolting operation matches the required safety levels as planned by the engineers. See pictures to the left.

Roofex Roofex features a high quality steel bar inside a smooth plastic sheathing which is fixed inside the borehole with cement or resin grout. The bolt also has an energy absorber which functions as a sliding element over the steel bar. This allows the bolt to extend outwards during sudden displacements such as rock burst or seismic events while still providing constant load capacity. This capability makes the Roofex rock bolt especially suitable for developing new, deep underground excavations in poor quality rock or in areas where rock burst or seismic events are frequent. The bolt can be produced in standard lengths typically used in mining and tunnelling, and the displacement capacity can be pre-selected during manufacture. See picture below.

Mathias Lewén Pre-calculated maximum deformation

Pre-calculated maximum deformation

1.

Roofex at installation

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Energy absorbing phase

3.

Roofex at max load and max deformation

Energy absorber (a sliding element)

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underground mining methods