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Greater understanding
REINFORCEMENT:EARTH conditions. The comparison shows that the Q-system is unsafe for large tunnels under squeezing ground conditions. A new correlation has been developed considering tunnel depth, tunnel radius, tunnel closure, and Rock Mass Number - i.e., ‘stress-free Q’ - to obtain reliable estimates of tunnel support pressures. (Authors)
Bolts and anchors 955247 Evaluation of glass fiber bolts for mining applications R. Pakalnis, D. Peterson & R. Poulin, Mining Engineering, 46(12), 1994, pp 1371-1372. A comprehensive project has been completed at the University of British Columbia that focused on the development ,of a commercially competitive composite cable bolt. Laboratory evaluation consisted of pull tests, preliminary shear tests, grout column testing and scanning electron microscope evaluation of the composite cable bolt. Field implementation at five underground mines throughout Canada were completed for technical and overall performance evaluation of the new product. (from Authors) 955248 A constitutive law for bond failure of fully-grouted cable bolts using a modified boek cell A. J. Hyett, W. F. Bawden, G. R. MacSporran & M. Moosavi, International Journal of Rock Mechanics & Mining Sciences, 32(l), 1995, pp 11-36. A series of pull tests were performed using fully-grouted seven-wire strand cable, in which the confining pressure at the outside of the cement annulus was maintained constant using a modified Hoek cell. The bond strength was shown to increase with confining pressure. The associated radial displacements at the outside of the cement annulus were measured and decreased with confining pressure. The data were used to develop a frictional-dilational model for cable bolt failure in both graphical and mathematical form. The latter is amenable to implementation in numerical programs, and presents an opportunity to incorporate realistic cable bolt behaviour into numerical analyses. The miniscule radial dilations induced by bond failure, which are responsible for the generation of radial pressure at the cable-grout interface and the development of frictional bond strength, explain the sensitivity of the bond strength to: 1) the grout quality, 2) the radial stiffness of the borehole wall and 3) mining-induced destressing. (Authors)
233A
critical role in the post-peak region, once adhesion is lost. (from Authors)
Direct rock support methods 955258 Ross Sbaft Pillar project at the Homestake Mine M. E. Poad, W. G. Pariseau & M. A. Laurenti, Mining Engineering, 47(l), 1995, pp 80-84. In 1986 an effort was initiated to determine shaft stability while recovering high-grade ore in a nearby pillar. Premining finite element simulations indicated the shaft would remain in elastic ground. Despite some initial concern during the first lifts, it appears that the bulk of the original reserve will be safely and profitably recovered. An integrated application of rock mechanics tools from laboratory testing through numerical modeling to mine measurements and observations contributed substantially to the operational success of the project. (from Authors)
Grouting 955251 Jet groutlng gains P. Tarricone, Civil Engineering - ASCE, 64(12), 1994, pp 4043. Jet grouting technology and its increasing uptake in the USA are described with reference to specific applications. These include: construction of soilcrete columns to protect river bridge abutment from scour, horizontal bottom sealing for contaminated groundwater control, ground treatment for tunnellling in clay, underpinning historic structures, improving caisson bearing capacity for a multi-level underground car park, and construction of a steel sheet-pile/soilbentonite cut-off barrier to separate a contaminated waste site from the Niagara River. (J.M.McLaughlin) 955252 Plastic surgery P. Wheeler, Ground Engineering, 27(8), 1994, p 24. Interlocking columns of plastically behaving slurry have been used to replace difftcult ground at the start of the metro extension in Rome, Italy. Columns were installed using a mix was rotary piling rig. The impermeable, flexible slu originally developed for use in landfill cutoffs. lm?? comprises 40-50 kg bentonite, 25Okg cement and 800 litres water. (J.M.McLaughlin)
Shotcrete Reinforced earth 955249 Sbotcrete support design in blocky ground: towards a deterministic approach S. V. L. Barrett & D. R. McCreath, Tunnelling & Underground Space Technology, IO(l), 1995, pp 79-89. In an attempt to gain some insight concerning the mechanisms which control shotcrete failure in blocky ground, four deterministic design models are presented which illustrate shotcrete’s effectiveness at supporting structurally defined blocks and wedges, thereby avoiding progressive loosening and destabilization of the rock mass around an opening. Results of analyses based on these models show that failure of shotcrete is generally a two-step process, governed initially by loss of adhesion to the rock, followed by flexural failure. These results indicate that while adhesion is of critical importance in maximizing the peak ground support capacity of the shotcrete, flexural strength and toughness play a
955253 Greater understanding M. Monro, International Construction, 34(l), 1995, pp 29-30. The use of geosynthetics to provide effective low-cost and convenient alternatives in a wide range of applications where conventional systems are expensive ,or environmentally unacceptable is discussed. The characteristics and benefits of geosynthetics are descirbed. The lining technologies available from different firms are outlined. (P.M.Taylor) 955254 Stress-strain analysis of geogrid-supported liners over subsurface cavities M. A. Gabr & T. J. Hunter, Geotechnical & Geological Engineering, 12(2), 1994, pp 65-86.
Bolts and anchors 955247 Evaluation of glass fiber bolts for mining applications R. Pakalnis, D. Peterson & R. Poulin, Mining Engineering, 46(12), 1994, pp 1371-1372. A comprehensive project has been completed at the University of British Columbia that focused on the development ,of a commercially competitive composite cable bolt. Laboratory evaluation consisted of pull tests, preliminary shear tests, grout column testing and scanning electron microscope evaluation of the composite cable bolt. Field implementation at five underground mines throughout Canada were completed for technical and overall performance evaluation of the new product. (from Authors) 955248 A constitutive law for bond failure of fully-grouted cable bolts using a modified boek cell A. J. Hyett, W. F. Bawden, G. R. MacSporran & M. Moosavi, International Journal of Rock Mechanics & Mining Sciences, 32(l), 1995, pp 11-36. A series of pull tests were performed using fully-grouted seven-wire strand cable, in which the confining pressure at the outside of the cement annulus was maintained constant using a modified Hoek cell. The bond strength was shown to increase with confining pressure. The associated radial displacements at the outside of the cement annulus were measured and decreased with confining pressure. The data were used to develop a frictional-dilational model for cable bolt failure in both graphical and mathematical form. The latter is amenable to implementation in numerical programs, and presents an opportunity to incorporate realistic cable bolt behaviour into numerical analyses. The miniscule radial dilations induced by bond failure, which are responsible for the generation of radial pressure at the cable-grout interface and the development of frictional bond strength, explain the sensitivity of the bond strength to: 1) the grout quality, 2) the radial stiffness of the borehole wall and 3) mining-induced destressing. (Authors)
233A
critical role in the post-peak region, once adhesion is lost. (from Authors)
Direct rock support methods 955258 Ross Sbaft Pillar project at the Homestake Mine M. E. Poad, W. G. Pariseau & M. A. Laurenti, Mining Engineering, 47(l), 1995, pp 80-84. In 1986 an effort was initiated to determine shaft stability while recovering high-grade ore in a nearby pillar. Premining finite element simulations indicated the shaft would remain in elastic ground. Despite some initial concern during the first lifts, it appears that the bulk of the original reserve will be safely and profitably recovered. An integrated application of rock mechanics tools from laboratory testing through numerical modeling to mine measurements and observations contributed substantially to the operational success of the project. (from Authors)
Grouting 955251 Jet groutlng gains P. Tarricone, Civil Engineering - ASCE, 64(12), 1994, pp 4043. Jet grouting technology and its increasing uptake in the USA are described with reference to specific applications. These include: construction of soilcrete columns to protect river bridge abutment from scour, horizontal bottom sealing for contaminated groundwater control, ground treatment for tunnellling in clay, underpinning historic structures, improving caisson bearing capacity for a multi-level underground car park, and construction of a steel sheet-pile/soilbentonite cut-off barrier to separate a contaminated waste site from the Niagara River. (J.M.McLaughlin) 955252 Plastic surgery P. Wheeler, Ground Engineering, 27(8), 1994, p 24. Interlocking columns of plastically behaving slurry have been used to replace difftcult ground at the start of the metro extension in Rome, Italy. Columns were installed using a mix was rotary piling rig. The impermeable, flexible slu originally developed for use in landfill cutoffs. lm?? comprises 40-50 kg bentonite, 25Okg cement and 800 litres water. (J.M.McLaughlin)
Shotcrete Reinforced earth 955249 Sbotcrete support design in blocky ground: towards a deterministic approach S. V. L. Barrett & D. R. McCreath, Tunnelling & Underground Space Technology, IO(l), 1995, pp 79-89. In an attempt to gain some insight concerning the mechanisms which control shotcrete failure in blocky ground, four deterministic design models are presented which illustrate shotcrete’s effectiveness at supporting structurally defined blocks and wedges, thereby avoiding progressive loosening and destabilization of the rock mass around an opening. Results of analyses based on these models show that failure of shotcrete is generally a two-step process, governed initially by loss of adhesion to the rock, followed by flexural failure. These results indicate that while adhesion is of critical importance in maximizing the peak ground support capacity of the shotcrete, flexural strength and toughness play a
955253 Greater understanding M. Monro, International Construction, 34(l), 1995, pp 29-30. The use of geosynthetics to provide effective low-cost and convenient alternatives in a wide range of applications where conventional systems are expensive ,or environmentally unacceptable is discussed. The characteristics and benefits of geosynthetics are descirbed. The lining technologies available from different firms are outlined. (P.M.Taylor) 955254 Stress-strain analysis of geogrid-supported liners over subsurface cavities M. A. Gabr & T. J. Hunter, Geotechnical & Geological Engineering, 12(2), 1994, pp 65-86.