gopers.my.id

The most commonly used mesh is probably welded mesh made of approximately 5 mm thick steel wire and having 100 mm square openings. The steel wire may be galvanised or not. The alternative has been an interwoven mesh known as chain link mesh.  The disadvantage of traditional chain link mesh compared with weld mesh has been the difficulty of applying shotcrete successfully through the smaller openings available.  This difficulty has now been overcome in a high strength, light weight chain link mesh with 100 mm openings which is easy to handle and can be made to conform to uneven rock surfaces more readily than weld mesh. A feature of this mesh is the fact that the intersections of the wires making up the squares in the mesh are twisted rather than simply linked or welded. Roth et al. (2004) describe static and dynamic tests on this mesh.  Mesh of this type is being used successfully at the Neves Corvo Mine, Portugal, where it has been particularly successful in rehabilitati...

It is the differential electrical potential between the anode (+) and the cathode (-) which is key to the moist corrosion example described above. This differential is primarily generated by the difference in oxygen availability between the edge and the centre of the water droplet. Differential potentials can also be generated by the presence (and contact) of dissimilar metals immersed in an oxygenated electrolyte solution (Illston et al., 1979; Bryson, 1987).  Corrosion induced by such a coupling can be extremely aggressive and can result from the designed use of dissimilar metals (steel cables with aluminum plates or anchors) or from the presence of cablebolts in a rich sulphide ore.  Indeed, rock bolts in sulphide ore bodies have significantly reduced service lives (Hoey and Dingley, 1971; Gunasekera, 1992). Corrosion cells can also be generated on cablebolt surfaces at the point where abrupt transitions in environment occur. These include differential grout coverage, for e...

It is perhaps remarkable to find that, although rock and cable bolts have been used in underground mining and construction for several decades (if not more than 100 years in the case of rock bolts), bolt elements and bolting systems continue to evolve and improve.  The papers presented to this symposium detail advances made in fully encapsulated resin and cement grouted bolts (Mikula 2004, Mould et al. 2004, Neindorf 2004), one pass mechanized bolting (Mikula 2004, Neindorf 2004) and bulbed cables (Yumlu & Bawden 2004), for example. The developments in ground support practices that have accompanied greater productivity, larger excavations and larger equipment are especially well-illustrated in the paper by Neindorf (2004) describing the evolution of ground support practices at the Mount Isa mine over the past 30 years. In a detailed and valuable review paper, Windsor (2004) concludes that “the quality and performance of cable bolts used to stabilise temporary, non-entry, produc...