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Durability of rock bolts
362A
Bolts and anchors
through compression compensation. The application of cable anchoring systems which utilise high strength strands and direct pull stressing is outlined. The principles underlying prestressing technology are also discussed.
See also: 906431 9O6316 Truss performance at Dutch Creek Mine, Colorado Seegmiller, B; Reeves, J Colliery Guard V238, N6, June 1990, P164-166 Longwall mining is used at Dutch Creek, where seams dip at about 12 deg to the west. Steel arch supports became useless when floor heave caused their legs to bend, and seam interactions led to shear of regular roof bolts. To counter these problems, high strength trusses were introduced in 1985. The early truss systems are described and current practice, using Continuous Entry Truss and Roktruss supports, is illustrated. 906317 Support with new cantilever bars and its application in the breakthrough of the Untersberg Tunnel (In German) Stipek, W; Weber, H Felsbau V8, N2, May 1990, P82-85
906321 Continuous monitoring of bolt tension and sag in a coal mine Unrug, K F; Nandy, S; Thompson, E Proc 7th Annual Workshop Generic Mineral Technology Center Mine Systems Design and Ground Control, Blacksburg, 22-24 October 1989 P15-21. Publ Blacksburg: Virginia Polytechnic Institute and State University, 1989 Optimization of the roof support system, using mechanical roof bolts, and gathering of information on tension of mechanical roof bolts from the time of installation are discussed. Comparison of roof performances between roofs with controlled weathering and a conventional system is made. Tests were conducted at six sites each consisting of an intersection and half break length in all four directions, and supported using mechanical roof bolts with different configurations.
A proposed support design for use in fractured rock masses under squeezing conditions is presented. Spile anchors are installed to give support ahead of the face and shotcrete added. Steel arches supported by radial anchors provide extended roof support. Results of model tests and first practical applications to a railway tunnel are described.
906322 Progress and problems in cable bolt design Pariseau, W G; Duan, F Proc 7th Annual Workshop Generic Mineral Technology Center Mine Systems Design and Ground Control, Blaeksburg, 22-24 October 1989 P23-24. Publ Blacksburg: Virginia Polytechnic Institute and State University, 1989
906318 Rock bolting World Min Equip V14, N4, April 1990, Pll-18
The equivalent-material properties approach to cable-bolt support layout is shown to be the only practical technique for including the effects of bolt reinforcement in an engineering analysis of the rock-mass response to excavation. The technique allows for rapid changes in bolting patterns without the need for rebuilding the finite element mesh, and the mesh size is reduced considerably. Considerable savings are achieved in model preparation time as well as computer storage and program execution costs.
The commonly used bolts and their particular features are introduced: cement grouted rebar, pretensioned resin grouted, expansion shell, cement grouted wedge type, split set, and swellex. Bolt material requirements are considered. Applications of cable bolting and truss support are described. Bolting machinery, in particular fully mechanised installation,is discussed. Manufacturers of bolts and bolting equipment are listed. 906319 Durability of rock bolts Helfrich, H K World Min Equip VI4, N4, April 1990, P19-22 The Swedish Rock Engineering Research Foundation (BeFo) is carrying out long term testing of rock bolts. Cement grouted (up to 20 years old), resin grouted (5-16 years) and swellex (7 years) bolts have been examined. Grouting quality was assessed acoustically using the Boltometer,and entire bolts overcored for laboratory examination. Overall quality of grouting was seen to be poor. Severe corrosion was seen for cement grouted bolts, much lower corrosion for ungrouted bolts. Despite reduced effectiveness of support, roofs with 20 year old cement grouted bolts showed no convergence. 906320 Cable anchor applications in South African collieries Naismith, W A Proc Symposium on Advances in Rock Mechanics in Underground Coal Mining, Witbank, 12 Sept 1989 P71-76. Publ Marshalltown: SANGORM, 1989 Prestressing is a technique that intentionally creates permanent stresses in a structure for the purpose of improving its strength, and thereby its behaviour under a required service condition. Prestressing of rock or concrete structures, which are weak in tension, with high tensile strength steel tendons counterbalances tensile stresses induced by working loads
906323 Stabilization of underground openings in jointed rock by fully grouted bolts Indaratna, B; Kaiser, P K Proc 15th Canadian Rock Mechanics Symposium, Rock Engineering for Underground Excavations, 3-4 October 1988 P195-206. Publ Toronto: University of Toronto, 1988 Behaviour of underground openings is governed by in situ stress field and the nature of the surrounding ground. An analysis of the behaviour of a bolt reinforced, heavily jointed rock mass is presented, taking into account bolt density and length and the equivalent plastic zone of the reinforced mass. Laboratory model simulations in rock like materials indicate that the analysis can be extended to describe the behaviour of openings in jointed rock. Capabilities and limitations of the model are discussed. 906324 Support of mechanical drivage under adverse ground conditions - a ease study Prasad, L; Raju, N M Proc International Symposium on Underground Engineering, New Delhi, 14-17 April 1988 II1, P325-332. Publ Rotterdam." A A Balkema, 1988 The roof bolting experiments and strata control investigatioris conducted in the VK 7 incline at Singareni colliery showed that bolts can be effectively used to support galleries with difficult roof conditions. These experiments also established quick setting grouted bolts along with steel sections as an effective
© 1990 Pergamon Press pie. Reproduction not permitted
Bolts and anchors
through compression compensation. The application of cable anchoring systems which utilise high strength strands and direct pull stressing is outlined. The principles underlying prestressing technology are also discussed.
See also: 906431 9O6316 Truss performance at Dutch Creek Mine, Colorado Seegmiller, B; Reeves, J Colliery Guard V238, N6, June 1990, P164-166 Longwall mining is used at Dutch Creek, where seams dip at about 12 deg to the west. Steel arch supports became useless when floor heave caused their legs to bend, and seam interactions led to shear of regular roof bolts. To counter these problems, high strength trusses were introduced in 1985. The early truss systems are described and current practice, using Continuous Entry Truss and Roktruss supports, is illustrated. 906317 Support with new cantilever bars and its application in the breakthrough of the Untersberg Tunnel (In German) Stipek, W; Weber, H Felsbau V8, N2, May 1990, P82-85
906321 Continuous monitoring of bolt tension and sag in a coal mine Unrug, K F; Nandy, S; Thompson, E Proc 7th Annual Workshop Generic Mineral Technology Center Mine Systems Design and Ground Control, Blacksburg, 22-24 October 1989 P15-21. Publ Blacksburg: Virginia Polytechnic Institute and State University, 1989 Optimization of the roof support system, using mechanical roof bolts, and gathering of information on tension of mechanical roof bolts from the time of installation are discussed. Comparison of roof performances between roofs with controlled weathering and a conventional system is made. Tests were conducted at six sites each consisting of an intersection and half break length in all four directions, and supported using mechanical roof bolts with different configurations.
A proposed support design for use in fractured rock masses under squeezing conditions is presented. Spile anchors are installed to give support ahead of the face and shotcrete added. Steel arches supported by radial anchors provide extended roof support. Results of model tests and first practical applications to a railway tunnel are described.
906322 Progress and problems in cable bolt design Pariseau, W G; Duan, F Proc 7th Annual Workshop Generic Mineral Technology Center Mine Systems Design and Ground Control, Blaeksburg, 22-24 October 1989 P23-24. Publ Blacksburg: Virginia Polytechnic Institute and State University, 1989
906318 Rock bolting World Min Equip V14, N4, April 1990, Pll-18
The equivalent-material properties approach to cable-bolt support layout is shown to be the only practical technique for including the effects of bolt reinforcement in an engineering analysis of the rock-mass response to excavation. The technique allows for rapid changes in bolting patterns without the need for rebuilding the finite element mesh, and the mesh size is reduced considerably. Considerable savings are achieved in model preparation time as well as computer storage and program execution costs.
The commonly used bolts and their particular features are introduced: cement grouted rebar, pretensioned resin grouted, expansion shell, cement grouted wedge type, split set, and swellex. Bolt material requirements are considered. Applications of cable bolting and truss support are described. Bolting machinery, in particular fully mechanised installation,is discussed. Manufacturers of bolts and bolting equipment are listed. 906319 Durability of rock bolts Helfrich, H K World Min Equip VI4, N4, April 1990, P19-22 The Swedish Rock Engineering Research Foundation (BeFo) is carrying out long term testing of rock bolts. Cement grouted (up to 20 years old), resin grouted (5-16 years) and swellex (7 years) bolts have been examined. Grouting quality was assessed acoustically using the Boltometer,and entire bolts overcored for laboratory examination. Overall quality of grouting was seen to be poor. Severe corrosion was seen for cement grouted bolts, much lower corrosion for ungrouted bolts. Despite reduced effectiveness of support, roofs with 20 year old cement grouted bolts showed no convergence. 906320 Cable anchor applications in South African collieries Naismith, W A Proc Symposium on Advances in Rock Mechanics in Underground Coal Mining, Witbank, 12 Sept 1989 P71-76. Publ Marshalltown: SANGORM, 1989 Prestressing is a technique that intentionally creates permanent stresses in a structure for the purpose of improving its strength, and thereby its behaviour under a required service condition. Prestressing of rock or concrete structures, which are weak in tension, with high tensile strength steel tendons counterbalances tensile stresses induced by working loads
906323 Stabilization of underground openings in jointed rock by fully grouted bolts Indaratna, B; Kaiser, P K Proc 15th Canadian Rock Mechanics Symposium, Rock Engineering for Underground Excavations, 3-4 October 1988 P195-206. Publ Toronto: University of Toronto, 1988 Behaviour of underground openings is governed by in situ stress field and the nature of the surrounding ground. An analysis of the behaviour of a bolt reinforced, heavily jointed rock mass is presented, taking into account bolt density and length and the equivalent plastic zone of the reinforced mass. Laboratory model simulations in rock like materials indicate that the analysis can be extended to describe the behaviour of openings in jointed rock. Capabilities and limitations of the model are discussed. 906324 Support of mechanical drivage under adverse ground conditions - a ease study Prasad, L; Raju, N M Proc International Symposium on Underground Engineering, New Delhi, 14-17 April 1988 II1, P325-332. Publ Rotterdam." A A Balkema, 1988 The roof bolting experiments and strata control investigatioris conducted in the VK 7 incline at Singareni colliery showed that bolts can be effectively used to support galleries with difficult roof conditions. These experiments also established quick setting grouted bolts along with steel sections as an effective
© 1990 Pergamon Press pie. Reproduction not permitted