The Use of Rockfall Protection Systems in Surface Mining Activity
ABSTRACT In many cases open pits in mountainous areas are subjected to the collapse of rock boulders (rockfall), which can reach the quarry area and create safety hazards for both personnel and mine infrastructure. The paper demonstrates that net fences widely used for control and risk mitigation of rockfall in civil and road constructions, can be used successfully also for mining activities, with special reference to ornamental stone quarries. A description of this protection technique and the design key points are highlighted and discussed.
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ABSTRACT: Flexible rockfall barriers are a common form of protection against falling blocks of rock and rock fragments (rockfall). These barriers consist of a system of cables, posts, and a mesh, and their capacity is typically quantified in terms of the threshold of impact (kinetic) energy at which the barrier fails. This threshold, referred to here as the “critical energy,” is often regarded as a constant. However, several studies have pointed out that there is no single representative value of critical energy for a given barrier. Instead, the critical energy decreases as the block size decreases, a phenomenon referred to as the “bullet effect.” In this paper, we present a simple analytical model for determining the critical energy of a flexible barrier. The model considers a block that impacts normally and centrally on the wire mesh, and rather than incorporate the structural details of the cables and posts explicitly, the supporting elements are replaced by springs of representative stiffness. The analysis reveals the dependence of the critical energy on the block size, as well as other relevant variables, and it provides physical insight into the impact problem. For example, it is shown that bending of the wire mesh during impact reduces the axial force that can be sustained within the wires, thus reducing the energy that can be absorbed. The formulas derived in the paper are straightforward to use, and the analytical predictions compare favorably with data available in the literature.Rock Mechanics and Rock Engineering 08/2013; 46(3):515-526. · 1.56 Impact Factor
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ABSTRACT: This paper describes an empirical method, called Rockfall Risk Assessment for Quarries (ROFRAQ), which assesses the risk associated with rockfalls in quarries. The method is based on a probabilistic approach that assumes that an accident occurs as a consequence of a sequence of events. This method has been applied to slopes in a number of quarries, and has proved useful in detecting troublesome slopes on the basis of empirical evidence. Thus far, it has been applied to around 100 slopes from various quarries of different rocks. These results show satisfactory agreement with results for empirical methods applied in the civil engineering field to highways and roads. The authors describe a case study of a granite aggregate quarry that highlights a number of issues in relation to practical application of the method.International Journal of Rock Mechanics and Mining Sciences. 01/2008;
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ABSTRACT: This study presents in situ experiments carried out at an open cut mine in New South Wales (Australia). The research intends to improve the current knowledge on drapery systems for rockfall hazard management in mining environments. Blocks were released from the top of two different sections of the highwall: with and without a rockfall drapery system installed on the highwall. The trajectories of the blocks were recorded by using synchronised stereo pairs of high speed cameras. Velocities were derived from the trajectories and used to gather rockfall motion parameters (restitution coefficients) and various energies.International Journal of Rock Mechanics and Mining Sciences 56:171–181. · 1.42 Impact Factor