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Percussive energy transfer in pneumatic top hammer rock drills
1 IOA
Design methods
Rock Breakage and Excavation
See also: 922196, 922475
922293 Efficient method in modeling variable mesh problems in geotechnical engineering Cheng, Y M; Tsui, Y Comput Geotech VII, NI, 1991, P37-57 Conventional methods of finite element analysis of excavation or embankment construction require changing the numbering of nodes (and possibly of elements) at each stage or using the concept of small stiffness air elements. These can be computationally inefficient and numerically unstable. A hybrid method has been developed, which combines the advantages of the two previous approaches, using 'true' air elements and 'air nodes'. It can be easily implemented in many existing programs with changing numbers of elements and nodes. The benefits are illustrated in the example of modelling a braced excavation construction.
922294 Eiffel tower stopes Suttill, K R Engng Min J V192, N7, July 1991, P37-39 Stopes tall enough to accommodate the Eiffel tower have been mined at Mount Isa Mines. These create unique engineering challenges for excavation, filling, and stability. Open stoping is the most common method. Stress analysis is by the displacement discontinuity code N F O L D in lead orebodies. In copper orebodies the boundary element program THREE is used in conjunction with IMPS (Integrated Mine Planning System). RDS (Ring Drilling System) is used to design drilling patterns. The 7mt/yr of backfill is planned with assistance of the programs FILDIS and FILPAK.
922295 Application of expert systems in geotechnical risk assessment for surface coal mine design Denby, B; Kizil, M S Int J Surf Min V5, N2, 1991, P75-82 ESDS (Expert Slope Design System) has been developed to process information from the geological and design models of a mine and to assess slope stability. Failure probability at a specific location, likely mode of failure, likely failure volume, and important factors in a potential instability are the output.
922296 Dynamic performance and design of underground excavations in jointed rock Brady, B H Proc ISRM International Symposium on Static and Dynamic Considerations in Rock Engineering, Swaziland, 10-12 September 1990 PI-II. Publ Rotterdam: A A Balkema, 1990 Whilst there has been progress in static design of underground excavations in jointed rock, very little has been done in dynamic design. A distinct element model is proposed which indicates that design in jointed rock must take into consideration the damage on joint surfaces due to plastic displacement. The model takes into account the dynamic properties of joints and dynamic behaviour of saturated fractured rock. The effects of the joint model on the excavation performance are examined. Mitigation of rockbursts and modification of local stresses are also discussed.
Drilling See also." 922040. 922245, 922249
922297 Percussive energy transfer in pneumatic top hammer rock drills Wu Changming let J Surf Min I/5, NI, /991. P33-38 A mathematical model of the percussive system of pneumatic rock drills is presented. It takes into account local deformation at piston and shank adapter impact ends and gives predictions in good agreement with field observations. Two dimensionless parameters are introduced, associated with piston mass, local deformation at impact ends, rod impedance, and characteristics of the rock-bit interface. Optimisation of energy transfer can be obtained if these parameters are maintained within certain ranges.
922298 Effects of gu-4ift pumping on borehole hydraulic conditions at Finnsjon, Sweden Andersson, J E; Andersson, P; Gustafsson, E J Hydrol V126. NIl2, Aug 1991. P113-127 Drilling fluid and drilling debris may be lost to the rock during drilling, with possible influence on hydraulic parameters in the vicinity of the bore or pollution of the groundwater. During rotary core drilling through a major fault zone, volume of flushing water and recovered debris were recorded. During penetration of the zone, all the flushing water was lost and recovered percentage of drilling detritus was very low. Gas lift pumping gave only marginal improvement. Air flush percussion drilling gave a larger amount of drilling debris, but the proportion lost to the rock was greater than for rotary core drilling.
922299 Effect of mechanical and physical properties on dust-producing characteristics of rocks from Zonguldak coal basin, Turkey. Technical note Guyaguler, T Trans lnst g i n Metall (Sect A g i n lnd) 1/100, May-Aug 1991, PA85-A87 Samples of 4 sandstones, 2 shales, and 1 conglomerate collected in Northern Turkey were used in drilling and dust sampling tests in a model gallery simulating a working face. Brittleness, toughness, compressive and tensile strengths, hardness, specific gravity, and hardgrove index of the rocks were measured in the laboratory. Regression analysis is used to examine correlations between dust make and rock properties. Brittleness:toughness ratio and hardness are the inherent properties most affecting dust producing index.
© 1992 Pergamon Press Ltd. Reproduction not permitted
Design methods
Rock Breakage and Excavation
See also: 922196, 922475
922293 Efficient method in modeling variable mesh problems in geotechnical engineering Cheng, Y M; Tsui, Y Comput Geotech VII, NI, 1991, P37-57 Conventional methods of finite element analysis of excavation or embankment construction require changing the numbering of nodes (and possibly of elements) at each stage or using the concept of small stiffness air elements. These can be computationally inefficient and numerically unstable. A hybrid method has been developed, which combines the advantages of the two previous approaches, using 'true' air elements and 'air nodes'. It can be easily implemented in many existing programs with changing numbers of elements and nodes. The benefits are illustrated in the example of modelling a braced excavation construction.
922294 Eiffel tower stopes Suttill, K R Engng Min J V192, N7, July 1991, P37-39 Stopes tall enough to accommodate the Eiffel tower have been mined at Mount Isa Mines. These create unique engineering challenges for excavation, filling, and stability. Open stoping is the most common method. Stress analysis is by the displacement discontinuity code N F O L D in lead orebodies. In copper orebodies the boundary element program THREE is used in conjunction with IMPS (Integrated Mine Planning System). RDS (Ring Drilling System) is used to design drilling patterns. The 7mt/yr of backfill is planned with assistance of the programs FILDIS and FILPAK.
922295 Application of expert systems in geotechnical risk assessment for surface coal mine design Denby, B; Kizil, M S Int J Surf Min V5, N2, 1991, P75-82 ESDS (Expert Slope Design System) has been developed to process information from the geological and design models of a mine and to assess slope stability. Failure probability at a specific location, likely mode of failure, likely failure volume, and important factors in a potential instability are the output.
922296 Dynamic performance and design of underground excavations in jointed rock Brady, B H Proc ISRM International Symposium on Static and Dynamic Considerations in Rock Engineering, Swaziland, 10-12 September 1990 PI-II. Publ Rotterdam: A A Balkema, 1990 Whilst there has been progress in static design of underground excavations in jointed rock, very little has been done in dynamic design. A distinct element model is proposed which indicates that design in jointed rock must take into consideration the damage on joint surfaces due to plastic displacement. The model takes into account the dynamic properties of joints and dynamic behaviour of saturated fractured rock. The effects of the joint model on the excavation performance are examined. Mitigation of rockbursts and modification of local stresses are also discussed.
Drilling See also." 922040. 922245, 922249
922297 Percussive energy transfer in pneumatic top hammer rock drills Wu Changming let J Surf Min I/5, NI, /991. P33-38 A mathematical model of the percussive system of pneumatic rock drills is presented. It takes into account local deformation at piston and shank adapter impact ends and gives predictions in good agreement with field observations. Two dimensionless parameters are introduced, associated with piston mass, local deformation at impact ends, rod impedance, and characteristics of the rock-bit interface. Optimisation of energy transfer can be obtained if these parameters are maintained within certain ranges.
922298 Effects of gu-4ift pumping on borehole hydraulic conditions at Finnsjon, Sweden Andersson, J E; Andersson, P; Gustafsson, E J Hydrol V126. NIl2, Aug 1991. P113-127 Drilling fluid and drilling debris may be lost to the rock during drilling, with possible influence on hydraulic parameters in the vicinity of the bore or pollution of the groundwater. During rotary core drilling through a major fault zone, volume of flushing water and recovered debris were recorded. During penetration of the zone, all the flushing water was lost and recovered percentage of drilling detritus was very low. Gas lift pumping gave only marginal improvement. Air flush percussion drilling gave a larger amount of drilling debris, but the proportion lost to the rock was greater than for rotary core drilling.
922299 Effect of mechanical and physical properties on dust-producing characteristics of rocks from Zonguldak coal basin, Turkey. Technical note Guyaguler, T Trans lnst g i n Metall (Sect A g i n lnd) 1/100, May-Aug 1991, PA85-A87 Samples of 4 sandstones, 2 shales, and 1 conglomerate collected in Northern Turkey were used in drilling and dust sampling tests in a model gallery simulating a working face. Brittleness, toughness, compressive and tensile strengths, hardness, specific gravity, and hardgrove index of the rocks were measured in the laboratory. Regression analysis is used to examine correlations between dust make and rock properties. Brittleness:toughness ratio and hardness are the inherent properties most affecting dust producing index.
© 1992 Pergamon Press Ltd. Reproduction not permitted