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Fast engineering analysis of alternative cable bolt patterns
178A specific cutting energy has then been used to develop diggability classifications to assess compatibility between BWE and overburden strata. 9233O7 Quality comparison of miniwlg equipment based on their technical characteristics Cokorilo, V; Milicic, M Mitt Sei Teclmoi 1113, N3, Dec 1991, P291-296 Technical, economic, ergonomic, and other parameters can affect the performance of mining machines. To enable comparison of these parameters, a machine technical characteristics matrix approach is proposed, where each column contains the characteristics of one machine, the same characteristics being compared in one row. It is illustrated using data for BWEs. 923308 Expert system for rock rippability assessment Koczanowski, M; Mostyn, G; MacGregor, F Proc 7th I S R M lntermutmud Cmqress on Rock Meclumies, Aachen, 16-20 September 1991 VI, P275-279. PUbl Rotterdam: A ,4 Balkema, 1991 Excavation costs can be significant in major projects. The more common methods of estimating rippability on the basis of machine and geological factors are outlined - Caterpillar charts, Weaver's method, Minty and Kearn's method, and PelFs method. These can be implemented in a method of combined assessment using the expert system Crystal. Comparisons are presented between field performance and expert system predictions for a wide variation of rock properties and machinery. 923309 First steps in developing an abrasive jet drill Summers, D; Yao, J
Proc 8tk Anmud Workshop Geswric Mineral Teclmology Center Mitw Systems Design and Ground Control, Reno, 5-6 November 1990 P49-60. Pubi Blacksburg: Virginia Polytechnic Institute and State University, 1990 An abrasive jet able to cut through rocks of nonuniform geology without deviation is under development. The DIAjet (Direct Injection of Abrasive) uses a charged pressure vessel between the pump and cutting nozzle to meter the abrasive with the waterjet stream. Tests to optimise reaction force as a function of flow rate and flow pressure are first described. Both garnet and steel abrasives have been evaluated. Expense, abrasive life and recoverability, and wear on the drill system are taken into account. Steel is preferred for the rocks cut (limestone, dolomite, granite, chert, quartzite) but garnet has some advantages in cutting ductile metal materials.
Rock and Soil Reinforcement and Support Bolts and anchors See also: 923065, 923448 923310 Extending the traditional role of rock reinforcement McKinnon, S D
In: MINTECH "91. Amman Review of International Mining Tecluadogy and Development P70-73. Publ London: Sterling Publications International, 1991 Rockbolting is common in civil and mining engineering. The support mechanisms can be either friction or adhesion. The unique aspects of the Swellex expandable bolt are examined. These bolts can be used in weak rock or soils, where their setting results in compaction and strengthening of the matrix material. Applications to stabilise a tunnel face in squeezing clay, in a soil slope of dense sand, in a tunnel in weak marl, and in a slope of weak friable rock are described. 923311 Helical anchors in dry and submerged sand subjected to
surcharge Ghaly, A; Hanna, A; Ranjan, G; Hanna, M J Geotech F ~ n g Die ASCE 1/117, NIO, Oct 1991, P14631470 Model tests on single helical anchors screwed into a dense sand deposit are described. The influence of surcharge of the top soil layers and of submersion of the soil are discussed. Nondimensional equations are developed relating parameters affecting uplift capacity and applied surcharge. The greater the embedment depth, the smaller the contribution to bearing capacity of surcharge. Where installation at great depth is difficult, surface surcharge can significantly increase bearing capacity or mitigate deleterious effects due to submergence. 923312 Studies on anchor strength in different types of rock masses Rame Gowda, B M; Saha, B K; Ghosh, A K Proc Indian Geoteclmical Conference, 1989, Geotecludqocs of Problematic Soils and Rocks, Visakla~tnam, 14-16 December 1989 VI, 1'451-454. Publ New Delhi: Sarita Prakashan, 1989 Type and diameter of bolt, type of grout, grouted length, and rock mass properties are the main factors affecting carrying capacity of grouted bolts or anchors. Pullout tests were carried out using Torsteel and round bar bolts and cement mortar and cement slurry grouts in sandstone, basalt, quartzite, granulite, pegmatite, and shale and mudstone rocks. Torsteel dowels and CS grout performed better than round bars and CM grout. Except in the case of very weak rock masses, pullout resistance was little influenced by rock mass type. 923313 Fast engineering analysis of alternative cable bolt patterns Duan, F; Pariseau, W G Proc 8tk Amman Workshop Generic Mineral Teclmology Center Mine Systems Design asd Grmmd Control, Reno, 5-6 November 1990 1"3-13. Publ Blacksburg: Virginia Polytechnic Institute and State University, 1990 The equivalent properties approach replaces the steel/grout/rock in the vicinity of a cable bolt hole by an equivalent homogeneous material. This is then used in the 3D
© 1992 Pergamon Press Ltd. Reproduction not permitted
179A finite element code UTAH3 to model the bolted rock mass. Proposed changes in bolt patterns can be made without changing the mesh, and mesh size is considerably reduced. This lowers the number of mesh constructions used in a design program and reduces computer storage and execution time requirements. Applications to vertical bench retreat (VBR) and vertical crater retreat (VCR) mining are illustrated.
Grouting
923314 Laboratory and numerical modelling of coal mine roof reinforcement systems Dar, S M; Smeiser, T W Proc International Conference om Meekanics of Jointed and Faulted Rock, Vienna, 18-20 April 1990 1'455-461. Publ Rotterdam: A A Balkema, 1990
Conventional cement grouting is not used for anchors in frozen rock because it is inefficient or deteriorates due to the formation of ice lenses in the setting cement. Deep boring to reach unfrozen rock or use of thermal protection systems increases costs. A modified cement based grout containing sodium nitrite as an antifreeze agent is proposed to overcome these problems. Field pullout tests are reported which demonstrate the efficiency of the modified grout in frozen rocks and permafrost.
See also: 923379 923317 New cemeat-based grout for grouting anchors in frozen rocks in the far north (In French) Benmokrane, B; Ballivy, G; Hernandez, P; Aitcin, P C Can Geoteeh J V28, N4, Aug 1991, P574-583
A full scale physical model of a 4.5m wide mine entry has been assembled using concrete blocks and sheets to represent coal measures strata. Underground loading has been simulated, and interaction between rock and supports and integrity of the bolted roof as a function of bolting pattern and roof strata characteristics have been studied. The model has been used in conjunction with finite element analysis to help improve roof support design. The two numerical codes used, BMINES and ANSYS, gave identical results, which correlate well with those of the physical model.
Direct rock support methods See also: 923467
923315 Study of shield support characteristics and their influence on the roof behaviour in coal longwalls Vervoort, A Min gel Teelmol VI3, N3, Dec 1991, P315-322
Results of an underground survey of shield support performance are summarised. Support geometrical and resistance parameters and roof characteristics show significant correlations with frequency of ground falls. This frequency increases with increasing unsupported distance and decreasing support pressure. Height of the roof cavities is influenced by these parameters and also by distance between coal face and the first hydraulic leg.
923316 Stability of cemented tnilings mine backfills Mitchell, R J Proc lntermrtiomd Symposiam on Computer and Physictd Modelli~ in Geoteekmcai Esgineerimg, Bangkok, 3..6 December 1986 P501-508. Publ Rotterdam: A A Balkema, 1989 Fill stability analyses must consider the geometry of the area to be supported. The use of sufficient cement to satisfy a lower bound free standing wall design approach is generally prohibitively expensive. Centrifuge model tests and analytical approaches were used to study stability of three typical fill geometries, steeply dipping and gently dipping narrow stopes and relatively wide stopes. It is demonstrated that efficient use of cement can be achieved by relying on soil arching and boundary shear effects, and introducing reinforcement. © 1992 Pergamon Press Ltd.
923318 Estimation of strength of silicate-gronted sand Kaga, M; Yonekura, R Soils Found V31, N3, Sept 1991, P43-59
Strength properties were measured for a range of mixtures of sands of different particle sizes and densities and grouts of different strengths. Grouted sand strength was proportional to sand density only over part of the density range examined. It was possible to describe the relation between grouted sand strength and pure grout strength by an exponential equation, which has been examined using the Mohr-Coulomb failure criterion and a two phase composite material model. Accurate prediction of grouted sand strength can be achieved over a wide range of material compositions. 923319 Recommendations on grouting for underground works (In English and French) Association Francaise des Travaux en Souterrain Tmmlg UndergroMd Space Teelmol V6, N4, 1991, P383-461
A comprehensive document updating the 1975 AFTES recommendations is presented. Basic areas for application are first outlined. The variety of grouts, their properties, and particular fields of use are detailed, including cement based, silicate, and resin grouts, plus quick set, foamed, expansive, or swelling derivatives. Penetrability, durability, safety and environmental aspects, and testing are next discussed. Drilling methods, patterns, and equipment, grouting parameters and injection methods, control, and uplift and resurgence are examined. Finally, preliminary studies, site assessment including laboratory testing, documentation, and costing are described. 923320 Development of grouting methods for Channel Tunnel United Kingdom segmental lining Annett, M F; Stewart, J Proc Tmmelliag "91, London, 14-18 April 1991 P173-179. Publ London: Elsevier, 1991 Grouts for fast mechanised tunnelling should set within ! 5 minutes of being pumped in place, have good anti-washout resistance, and long life prior to addition of accelerator. For major projects they should be compatible with long pumping lines. The basic grout material specified for the UK side of the Channel Tunnel is a 3:1 PFA-OPC grout, with anti-washout additive and a modified silicate liquid accelerator. Evaluation trials including wet ground conditions are described. Site trials resulted in further plant modifications, leading to the system for which a patent was applied in 1988.
Reproductionnot permitted
Proc 8tk Anmud Workshop Geswric Mineral Teclmology Center Mitw Systems Design and Ground Control, Reno, 5-6 November 1990 P49-60. Pubi Blacksburg: Virginia Polytechnic Institute and State University, 1990 An abrasive jet able to cut through rocks of nonuniform geology without deviation is under development. The DIAjet (Direct Injection of Abrasive) uses a charged pressure vessel between the pump and cutting nozzle to meter the abrasive with the waterjet stream. Tests to optimise reaction force as a function of flow rate and flow pressure are first described. Both garnet and steel abrasives have been evaluated. Expense, abrasive life and recoverability, and wear on the drill system are taken into account. Steel is preferred for the rocks cut (limestone, dolomite, granite, chert, quartzite) but garnet has some advantages in cutting ductile metal materials.
Rock and Soil Reinforcement and Support Bolts and anchors See also: 923065, 923448 923310 Extending the traditional role of rock reinforcement McKinnon, S D
In: MINTECH "91. Amman Review of International Mining Tecluadogy and Development P70-73. Publ London: Sterling Publications International, 1991 Rockbolting is common in civil and mining engineering. The support mechanisms can be either friction or adhesion. The unique aspects of the Swellex expandable bolt are examined. These bolts can be used in weak rock or soils, where their setting results in compaction and strengthening of the matrix material. Applications to stabilise a tunnel face in squeezing clay, in a soil slope of dense sand, in a tunnel in weak marl, and in a slope of weak friable rock are described. 923311 Helical anchors in dry and submerged sand subjected to
surcharge Ghaly, A; Hanna, A; Ranjan, G; Hanna, M J Geotech F ~ n g Die ASCE 1/117, NIO, Oct 1991, P14631470 Model tests on single helical anchors screwed into a dense sand deposit are described. The influence of surcharge of the top soil layers and of submersion of the soil are discussed. Nondimensional equations are developed relating parameters affecting uplift capacity and applied surcharge. The greater the embedment depth, the smaller the contribution to bearing capacity of surcharge. Where installation at great depth is difficult, surface surcharge can significantly increase bearing capacity or mitigate deleterious effects due to submergence. 923312 Studies on anchor strength in different types of rock masses Rame Gowda, B M; Saha, B K; Ghosh, A K Proc Indian Geoteclmical Conference, 1989, Geotecludqocs of Problematic Soils and Rocks, Visakla~tnam, 14-16 December 1989 VI, 1'451-454. Publ New Delhi: Sarita Prakashan, 1989 Type and diameter of bolt, type of grout, grouted length, and rock mass properties are the main factors affecting carrying capacity of grouted bolts or anchors. Pullout tests were carried out using Torsteel and round bar bolts and cement mortar and cement slurry grouts in sandstone, basalt, quartzite, granulite, pegmatite, and shale and mudstone rocks. Torsteel dowels and CS grout performed better than round bars and CM grout. Except in the case of very weak rock masses, pullout resistance was little influenced by rock mass type. 923313 Fast engineering analysis of alternative cable bolt patterns Duan, F; Pariseau, W G Proc 8tk Amman Workshop Generic Mineral Teclmology Center Mine Systems Design asd Grmmd Control, Reno, 5-6 November 1990 1"3-13. Publ Blacksburg: Virginia Polytechnic Institute and State University, 1990 The equivalent properties approach replaces the steel/grout/rock in the vicinity of a cable bolt hole by an equivalent homogeneous material. This is then used in the 3D
© 1992 Pergamon Press Ltd. Reproduction not permitted
179A finite element code UTAH3 to model the bolted rock mass. Proposed changes in bolt patterns can be made without changing the mesh, and mesh size is considerably reduced. This lowers the number of mesh constructions used in a design program and reduces computer storage and execution time requirements. Applications to vertical bench retreat (VBR) and vertical crater retreat (VCR) mining are illustrated.
Grouting
923314 Laboratory and numerical modelling of coal mine roof reinforcement systems Dar, S M; Smeiser, T W Proc International Conference om Meekanics of Jointed and Faulted Rock, Vienna, 18-20 April 1990 1'455-461. Publ Rotterdam: A A Balkema, 1990
Conventional cement grouting is not used for anchors in frozen rock because it is inefficient or deteriorates due to the formation of ice lenses in the setting cement. Deep boring to reach unfrozen rock or use of thermal protection systems increases costs. A modified cement based grout containing sodium nitrite as an antifreeze agent is proposed to overcome these problems. Field pullout tests are reported which demonstrate the efficiency of the modified grout in frozen rocks and permafrost.
See also: 923379 923317 New cemeat-based grout for grouting anchors in frozen rocks in the far north (In French) Benmokrane, B; Ballivy, G; Hernandez, P; Aitcin, P C Can Geoteeh J V28, N4, Aug 1991, P574-583
A full scale physical model of a 4.5m wide mine entry has been assembled using concrete blocks and sheets to represent coal measures strata. Underground loading has been simulated, and interaction between rock and supports and integrity of the bolted roof as a function of bolting pattern and roof strata characteristics have been studied. The model has been used in conjunction with finite element analysis to help improve roof support design. The two numerical codes used, BMINES and ANSYS, gave identical results, which correlate well with those of the physical model.
Direct rock support methods See also: 923467
923315 Study of shield support characteristics and their influence on the roof behaviour in coal longwalls Vervoort, A Min gel Teelmol VI3, N3, Dec 1991, P315-322
Results of an underground survey of shield support performance are summarised. Support geometrical and resistance parameters and roof characteristics show significant correlations with frequency of ground falls. This frequency increases with increasing unsupported distance and decreasing support pressure. Height of the roof cavities is influenced by these parameters and also by distance between coal face and the first hydraulic leg.
923316 Stability of cemented tnilings mine backfills Mitchell, R J Proc lntermrtiomd Symposiam on Computer and Physictd Modelli~ in Geoteekmcai Esgineerimg, Bangkok, 3..6 December 1986 P501-508. Publ Rotterdam: A A Balkema, 1989 Fill stability analyses must consider the geometry of the area to be supported. The use of sufficient cement to satisfy a lower bound free standing wall design approach is generally prohibitively expensive. Centrifuge model tests and analytical approaches were used to study stability of three typical fill geometries, steeply dipping and gently dipping narrow stopes and relatively wide stopes. It is demonstrated that efficient use of cement can be achieved by relying on soil arching and boundary shear effects, and introducing reinforcement. © 1992 Pergamon Press Ltd.
923318 Estimation of strength of silicate-gronted sand Kaga, M; Yonekura, R Soils Found V31, N3, Sept 1991, P43-59
Strength properties were measured for a range of mixtures of sands of different particle sizes and densities and grouts of different strengths. Grouted sand strength was proportional to sand density only over part of the density range examined. It was possible to describe the relation between grouted sand strength and pure grout strength by an exponential equation, which has been examined using the Mohr-Coulomb failure criterion and a two phase composite material model. Accurate prediction of grouted sand strength can be achieved over a wide range of material compositions. 923319 Recommendations on grouting for underground works (In English and French) Association Francaise des Travaux en Souterrain Tmmlg UndergroMd Space Teelmol V6, N4, 1991, P383-461
A comprehensive document updating the 1975 AFTES recommendations is presented. Basic areas for application are first outlined. The variety of grouts, their properties, and particular fields of use are detailed, including cement based, silicate, and resin grouts, plus quick set, foamed, expansive, or swelling derivatives. Penetrability, durability, safety and environmental aspects, and testing are next discussed. Drilling methods, patterns, and equipment, grouting parameters and injection methods, control, and uplift and resurgence are examined. Finally, preliminary studies, site assessment including laboratory testing, documentation, and costing are described. 923320 Development of grouting methods for Channel Tunnel United Kingdom segmental lining Annett, M F; Stewart, J Proc Tmmelliag "91, London, 14-18 April 1991 P173-179. Publ London: Elsevier, 1991 Grouts for fast mechanised tunnelling should set within ! 5 minutes of being pumped in place, have good anti-washout resistance, and long life prior to addition of accelerator. For major projects they should be compatible with long pumping lines. The basic grout material specified for the UK side of the Channel Tunnel is a 3:1 PFA-OPC grout, with anti-washout additive and a modified silicate liquid accelerator. Evaluation trials including wet ground conditions are described. Site trials resulted in further plant modifications, leading to the system for which a patent was applied in 1988.
Reproductionnot permitted