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Force-displacement behavior of flexible plate anchors Technical note
304A
935283 Experimental investigation of the energy-size reduction relationship in comminution using fractal theory Li Gongbo; Xu Xiaohe Miner Engng V6, N2, Feb 1993, P163-172
Rock and Soil Reinforcement and Support
An equation is presented for the relation between energy and size reduction of a brittle solid in which the exponent (n), related to material and size reduction method, is in the form (4-Ds), where Ds is the fractal dimension of the rock-fracture particle surface. The traditional equations of Rittinger, Bond, and Kick can be obtained by assigning values of n of 2, 1.5, and 1 respectively and integrating. Image analysis of 450 particle profiles chosen from 45 samples obtained by static compression, impact, jaw crushing, and ball mill grinding was used in development of the base equation.
Bolts and anchors
935284 Measurement of fracture energy during single-particle fracture King, R P; Bourgeois, F Miner Engng V6, N4, April 1993, P353-367 The population balance model provides a good description of the comminution of brittle particulate material. The breakage function, which describes the distribution of daughter fragments after fracture events, plays a central role in the population balance model, and correct prediction of this function is essential for scaling from laboratory to industrial size. The operation and calibration is described of the ultrafast load cell, which allows measurement of the distribution of fracture energies amongst particles and the relation between the breakage function and the impact energy of single particles and beds of particles during impact.
935285 Analysis of SAG mill grinding and liberation tests Austin, L G; Sutherland, D N; Gottlieb, P Miner Engng V6, N5, May 1993, P491-507 Size distributions for an ore ground in a pilot scale semiautogeneous mill were used to calculate apparent specific rates of breakage, S(x). It is demonstrated that S(x) values are better considered as specific rates of production. These values vary with particle size in different ways for autogeneous, 4%, and 8% ball load ct, nditions. Distribution of sulphide with particle size was different from that of the total mass. S(x) values should not be used to predict sulphide distribution. The Operating Work Index gave false conclusions regarding the efficiency of the SAG mill. Image analysis shows consistently better liberation as smaller sizes are considered.
935287 Determining bolt bearing capacity under composite stress (In German) Klein, J; Krahe, J Gluckaaf-forschungsh V54, N2, ,4pril 1993, P62-65 Methods of predicting the capacity of rock bolts as used in mining are examined. Effects of varying normal stress or introducing different shear stresses are described. Contributions from the grout or plastic deformation of the steel bolt are also investigated. Ungrouted expansion bolts and pretensioned bolts are included in the analysis. Test results indicate that bending stresses at the bolt head lower bearing capacity.
935288 Examination of uplift capacity of helical anchors in clays. Technical note Rao, N S; Prasad, Y V S N J Geotech Engng Div ASCE VII9, N2, Feb 1993, P352-357 An attempt has been made to predict the bearing capacity of helical anchors in clays and silts on the basis of measured shear strength of the soil. A cylindrical failure surface between the top and bottom helical plates is assumed. Effects of spacing of the plates were also examined in model tests. The test results verify the predicted capacities. Where spacing ratio is 1.5, failure surfaces are not cylindrical and modifications to the predictive formulae are required.
935289 Force-displacement behavior of flexible plate anchors. Technical note Othman, M A; Edil, T B J Geotech Engng Div ASCE Vl19, N3, March 1993, P590597 Uplift tests were carried out on 0.3m diameter anchors at depth 0.6m in sand in a 3m cube test pit. Effects of anchor flexibility on the force-displacement behaviour and influences of sand density and installation method were examined. Predictions of four analyses were compared to test data, with generally good correlation for medium dense sands. Where avoidance of catastrophic failure rather than displacement is the main design criterion, the flexible anchor has advantages over the rigid plate.
Machine excavation See also: 935098
935286 Rock cutting with rotating high-pressure water jets (In German) Hlavac, L; Foldyna, J; Momber, A Glnckaf-forschlmgsh 1/54, N2, April 1993, P58-62 Equations are presented for approximate prediction of kerf depth possible with rotating high pressure waterjet tools with dual nozzle motion. The relations established allow rapid optimization of tool working. Equations are also presented for rocking-action tools, which may form the basis of further development of tools of this type.
935290 Comparative analysis of rock bolting of underground excavations Pistone, R S Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V2, P1203-1205. Publ Rotterdam." ,4 ,4 Balkema, 1991 The Rio Grande hydroelectric plant in Argentina was completed in 1986 in gneissic rock ranging from good to very low quality. Quantities, lengths, and nominal support pressures for rock bolts installed in the caverns and tunnels are analysed in relation to size of the opening and quality of the rock mass. The necessary increase in support intensity as opening width increases and/or rock mass quality falls is a consequence of expected natural arch performance.
© 1993 Pergamon Press Ltd. Reproduction not permitted
935283 Experimental investigation of the energy-size reduction relationship in comminution using fractal theory Li Gongbo; Xu Xiaohe Miner Engng V6, N2, Feb 1993, P163-172
Rock and Soil Reinforcement and Support
An equation is presented for the relation between energy and size reduction of a brittle solid in which the exponent (n), related to material and size reduction method, is in the form (4-Ds), where Ds is the fractal dimension of the rock-fracture particle surface. The traditional equations of Rittinger, Bond, and Kick can be obtained by assigning values of n of 2, 1.5, and 1 respectively and integrating. Image analysis of 450 particle profiles chosen from 45 samples obtained by static compression, impact, jaw crushing, and ball mill grinding was used in development of the base equation.
Bolts and anchors
935284 Measurement of fracture energy during single-particle fracture King, R P; Bourgeois, F Miner Engng V6, N4, April 1993, P353-367 The population balance model provides a good description of the comminution of brittle particulate material. The breakage function, which describes the distribution of daughter fragments after fracture events, plays a central role in the population balance model, and correct prediction of this function is essential for scaling from laboratory to industrial size. The operation and calibration is described of the ultrafast load cell, which allows measurement of the distribution of fracture energies amongst particles and the relation between the breakage function and the impact energy of single particles and beds of particles during impact.
935285 Analysis of SAG mill grinding and liberation tests Austin, L G; Sutherland, D N; Gottlieb, P Miner Engng V6, N5, May 1993, P491-507 Size distributions for an ore ground in a pilot scale semiautogeneous mill were used to calculate apparent specific rates of breakage, S(x). It is demonstrated that S(x) values are better considered as specific rates of production. These values vary with particle size in different ways for autogeneous, 4%, and 8% ball load ct, nditions. Distribution of sulphide with particle size was different from that of the total mass. S(x) values should not be used to predict sulphide distribution. The Operating Work Index gave false conclusions regarding the efficiency of the SAG mill. Image analysis shows consistently better liberation as smaller sizes are considered.
935287 Determining bolt bearing capacity under composite stress (In German) Klein, J; Krahe, J Gluckaaf-forschungsh V54, N2, ,4pril 1993, P62-65 Methods of predicting the capacity of rock bolts as used in mining are examined. Effects of varying normal stress or introducing different shear stresses are described. Contributions from the grout or plastic deformation of the steel bolt are also investigated. Ungrouted expansion bolts and pretensioned bolts are included in the analysis. Test results indicate that bending stresses at the bolt head lower bearing capacity.
935288 Examination of uplift capacity of helical anchors in clays. Technical note Rao, N S; Prasad, Y V S N J Geotech Engng Div ASCE VII9, N2, Feb 1993, P352-357 An attempt has been made to predict the bearing capacity of helical anchors in clays and silts on the basis of measured shear strength of the soil. A cylindrical failure surface between the top and bottom helical plates is assumed. Effects of spacing of the plates were also examined in model tests. The test results verify the predicted capacities. Where spacing ratio is 1.5, failure surfaces are not cylindrical and modifications to the predictive formulae are required.
935289 Force-displacement behavior of flexible plate anchors. Technical note Othman, M A; Edil, T B J Geotech Engng Div ASCE Vl19, N3, March 1993, P590597 Uplift tests were carried out on 0.3m diameter anchors at depth 0.6m in sand in a 3m cube test pit. Effects of anchor flexibility on the force-displacement behaviour and influences of sand density and installation method were examined. Predictions of four analyses were compared to test data, with generally good correlation for medium dense sands. Where avoidance of catastrophic failure rather than displacement is the main design criterion, the flexible anchor has advantages over the rigid plate.
Machine excavation See also: 935098
935286 Rock cutting with rotating high-pressure water jets (In German) Hlavac, L; Foldyna, J; Momber, A Glnckaf-forschlmgsh 1/54, N2, April 1993, P58-62 Equations are presented for approximate prediction of kerf depth possible with rotating high pressure waterjet tools with dual nozzle motion. The relations established allow rapid optimization of tool working. Equations are also presented for rocking-action tools, which may form the basis of further development of tools of this type.
935290 Comparative analysis of rock bolting of underground excavations Pistone, R S Proc 7th ISRM International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V2, P1203-1205. Publ Rotterdam." ,4 ,4 Balkema, 1991 The Rio Grande hydroelectric plant in Argentina was completed in 1986 in gneissic rock ranging from good to very low quality. Quantities, lengths, and nominal support pressures for rock bolts installed in the caverns and tunnels are analysed in relation to size of the opening and quality of the rock mass. The necessary increase in support intensity as opening width increases and/or rock mass quality falls is a consequence of expected natural arch performance.
© 1993 Pergamon Press Ltd. Reproduction not permitted