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Use of ground anchors in residual soils
60A discussed. The importance of in-seam testing is outlined and a description of an in-seam test, currently under development at the University of Nottingham, is included.
Bolts and anchors
862167 Model describing rock cutting with conical picks. ,Technical note Ranman, K E Rock Mech V18, N2, April-June 1985, P131-140
862170 Rock bolting: which system is right for you? Rogers, B S Can Min J V106, N7, July 1985, P36-44
Earlier models of rock cutting do not examine continuous cutting, where the previous cutting may affect chip geometry and cutting forces. Two series of tests are described which examine the validity of a proposed model of continuous cutting. The first examines the chip geometry - size and shape distribution; the second involves measurements of the actual cutting force.
862168 Cutting trials with a water-jet-amisted i-am tester Evans, R J; Handewith, H J; Hood, M In: Rock Mechanics in Productivity and Protection (Proceedings of the Twenty-F@ Symposium on Rock Mechanics, Evanston, Iffiis, 25-27 June 1984) P767-773. Pub1 New York: AIME, 1984
An in-seam tester, a single pick instrument developed to monitor pick cutting forces, was used to establish criteria needed to develop a water-jet assisted rotary drum cutter using water pressure in the 3000-IOOOOpsi range. Data are presented for laboratory and in-seam trials on synthetic and natural coal, sandstone and limestone, using conical and flat bits. Data analysis suggests that water jets can significantly reduce pick forces.
See also: 86,7240
The range of rock bolts and rock bolting equipment currently available is briefly reviewed.
862171 Reinforcement analysis and design of mechanical roof bolting systems in horizontally bedded mine roofs Tang, D H Y; Peng, S S Int J Min Engng V3, N1, March 1985, PI-25 The flexural behaviour of three strata types is investigated in terms of the effects of roof span, horizontal stress, thickness, and Young’s modulus of the lowest strata. The suspension reinforcement mechanism is analysed using beam-column theory. The equations for the maximum bending stress, deflection and transferred bolt load for the bolted strata are derived. The friction reinforcement mechanism is investigated. A computer program and nomographs are developed for the determination of proper bolting pattern and bolt tension.
862172 Use of ground anchors in residual soils Kannan, R; Broms. B B Proc International Conference on Case Histories in Geotechnical Engineering, Rolla, Missouri, 6-11 May 1984 VI, P377-385. Pub1 St Louis: Geotechnical Engineering, 1984
862169 Finite element simulation of rock cntting: a fracture mechanics approach Saouma, V E; Kleinosky, M J In: Rock Mechanics in Productivity and Protection (Proceedings of the Twenty-Fiflh Symposium on Rock Mechanics, Evanston, Illinois, 25-27 June 1984) P792-799. Pub1 New York: AIME. 1984
The process of crack formation and propagation in front of a disc cutter or drag bit cutter has been numerically investigated. A finite element model, SICRAP, written to simulate mixed mode crack propagation under linear elastic fracture mechanics, was used. Two test problems were investigated. The first provided interesting qualitative results, the second showed correlation with experimental results for chip formation on Berea sandstone with a drag bit cutter, indicating that the procedure used is capable of modelling rock cutting.
Several case studies are presented where ground anchors have been used in residual soils of Singapore and Malaysia. Deep excavations in these soils were rare until the early 1970s. Analytical design methods and finite element analysis, which give a good insight into the soil-anchor interaction, are gaining popularity. Post grouting is often used for anchors in residual soils and has been found successful.
862173 Methods of designing mechanical roof bolting in horizontally bedded strata Tang, D H Y; Peng, S S In: Rock Mechanics in ProaWivity and Protection (Proceedings of the Twenty-Fijih Symposinm on Rock Mechanics, Evanston, Illinois, 25-27 3nne 1984) P6JS-626. Pub1 New York: AIME. 1984
Rock and Soil Reinforcement and Support See: 86225 7 0
The reinforcement mechanism of roof bolts is analysed using beam-column theory. Equations are derived for maximum bending stress, deflection and transferred bolt load. Reinforcement by the suspension effect for competent roofs and the friction effect, where incompetent strata are effectively ‘welded’ into one thick stratum, is considered. Equal spacing of bolts is suggested for the suspension effect, while bolts should be spaced on the equal shear force concept for the friction effect.
1986 Pergamon Press Ltd. Reproduction
not permitted
Bolts and anchors
862167 Model describing rock cutting with conical picks. ,Technical note Ranman, K E Rock Mech V18, N2, April-June 1985, P131-140
862170 Rock bolting: which system is right for you? Rogers, B S Can Min J V106, N7, July 1985, P36-44
Earlier models of rock cutting do not examine continuous cutting, where the previous cutting may affect chip geometry and cutting forces. Two series of tests are described which examine the validity of a proposed model of continuous cutting. The first examines the chip geometry - size and shape distribution; the second involves measurements of the actual cutting force.
862168 Cutting trials with a water-jet-amisted i-am tester Evans, R J; Handewith, H J; Hood, M In: Rock Mechanics in Productivity and Protection (Proceedings of the Twenty-F@ Symposium on Rock Mechanics, Evanston, Iffiis, 25-27 June 1984) P767-773. Pub1 New York: AIME, 1984
An in-seam tester, a single pick instrument developed to monitor pick cutting forces, was used to establish criteria needed to develop a water-jet assisted rotary drum cutter using water pressure in the 3000-IOOOOpsi range. Data are presented for laboratory and in-seam trials on synthetic and natural coal, sandstone and limestone, using conical and flat bits. Data analysis suggests that water jets can significantly reduce pick forces.
See also: 86,7240
The range of rock bolts and rock bolting equipment currently available is briefly reviewed.
862171 Reinforcement analysis and design of mechanical roof bolting systems in horizontally bedded mine roofs Tang, D H Y; Peng, S S Int J Min Engng V3, N1, March 1985, PI-25 The flexural behaviour of three strata types is investigated in terms of the effects of roof span, horizontal stress, thickness, and Young’s modulus of the lowest strata. The suspension reinforcement mechanism is analysed using beam-column theory. The equations for the maximum bending stress, deflection and transferred bolt load for the bolted strata are derived. The friction reinforcement mechanism is investigated. A computer program and nomographs are developed for the determination of proper bolting pattern and bolt tension.
862172 Use of ground anchors in residual soils Kannan, R; Broms. B B Proc International Conference on Case Histories in Geotechnical Engineering, Rolla, Missouri, 6-11 May 1984 VI, P377-385. Pub1 St Louis: Geotechnical Engineering, 1984
862169 Finite element simulation of rock cntting: a fracture mechanics approach Saouma, V E; Kleinosky, M J In: Rock Mechanics in Productivity and Protection (Proceedings of the Twenty-Fiflh Symposium on Rock Mechanics, Evanston, Illinois, 25-27 June 1984) P792-799. Pub1 New York: AIME. 1984
The process of crack formation and propagation in front of a disc cutter or drag bit cutter has been numerically investigated. A finite element model, SICRAP, written to simulate mixed mode crack propagation under linear elastic fracture mechanics, was used. Two test problems were investigated. The first provided interesting qualitative results, the second showed correlation with experimental results for chip formation on Berea sandstone with a drag bit cutter, indicating that the procedure used is capable of modelling rock cutting.
Several case studies are presented where ground anchors have been used in residual soils of Singapore and Malaysia. Deep excavations in these soils were rare until the early 1970s. Analytical design methods and finite element analysis, which give a good insight into the soil-anchor interaction, are gaining popularity. Post grouting is often used for anchors in residual soils and has been found successful.
862173 Methods of designing mechanical roof bolting in horizontally bedded strata Tang, D H Y; Peng, S S In: Rock Mechanics in ProaWivity and Protection (Proceedings of the Twenty-Fijih Symposinm on Rock Mechanics, Evanston, Illinois, 25-27 3nne 1984) P6JS-626. Pub1 New York: AIME. 1984
Rock and Soil Reinforcement and Support See: 86225 7 0
The reinforcement mechanism of roof bolts is analysed using beam-column theory. Equations are derived for maximum bending stress, deflection and transferred bolt load. Reinforcement by the suspension effect for competent roofs and the friction effect, where incompetent strata are effectively ‘welded’ into one thick stratum, is considered. Equal spacing of bolts is suggested for the suspension effect, while bolts should be spaced on the equal shear force concept for the friction effect.
1986 Pergamon Press Ltd. Reproduction
not permitted