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Block modelling of jointed cliffs
305A closed end steel pipe pile is instrumented at about lm intervals with clusters containing a high-capacity axial load cell, one or two surface stress transducers, each containing a temperature sensor, and a pore pressure measurement unit. Problems with measurement of pore pressure in strongly dilatant soils are discussed. The reliability of the system is demonstrated using test data from a stiff clay site. 925249 Development of a combination incllnometer-deflectometer and ADAAS. Technical note Kumbhojkar, A S; Israel, T D; Arnstan, D; Lee, S M Geotech Test J VI4, N4o Dec 1991, P451-456
A combination inclinometer-deflectometer (CID) has been developed, consisting of two legs of equal length enclosing a horizontal servoaccelerometer (HSA) and a flexure transducer in a waterproof housing. It is combined with a new automated data acquisition and analysis system (ADAAS) to provide a hybrid instrument with enhanced accuracy, reliability, and precision of ground movement measurement. 925250 Machine performance monitoring in surface mines Hendricks, C; Peck J; Scoble, M J Min Engng V44. N3, March 1992, P243-250
Field trials using microprocessor based instruments to monitor operating parameters of rotary blasthole drills and mining shovels are reported. Penetration rate, rotary speed, torque, pulldown pressure, and specific energy have been recorded. Pattern recognition techniques are used to correlate these parameters with variations in rock type and strength. Inferred and logged geology are illustrated. Shovel monitoring allows assessment of how effectively the drilling-derived data have been used in blast design, interpreted in terms of excavator performance related to muckpile characteristics. 925251 Application of a microseismic system at Western Deep Levels van Zyl Brink, A Proc 2nd International Symposium on Rockbursts and Seismicity in Mines, Minneapolis, 8-10 June 1988 P355-361. Publ Rotterdam: A A Balkema, 1990
Microseismic monitoring has been carried out for 20 years at Western Deep Levels, with a system capable of real time prediction of rockburst installed in 1980. Precursory phenomena are described and a number of instances where it was possible to take preventative or mitigative action are presented. The system is also used to monitor fluid injection destressing, monitor failure processes in stabilising pillars, and in study of basic seismological phenomena. 925252 Monitoring of seismicity and measures implemented to alleviate rockburst damage at Kloof A division of Kloof Gold Mining Co. Ltd Waldeck, H G Proc 2nd International Symposium on Rockbursts and Seismicity in Mines, Minneapolis, 8-10 June 1988 P395-400. Publ Rotterdam: A A Balkema, 1990
Rockburst at Kloof A became so severe as the mined-out areas became extensive that stabilising pillars were necessary. A seismic network of 15 geophones was installed in boreholes above and below the Ventersdorp Contact Reef, starting in 1983. Data acquired over 3 years indicate seismic a- and b-
values of 3.45 and 0.89 respectively. Major events are less frequent than in other local mines. These data are used in computer simulations to optimise mining methods. Longwalling with strike stabilising pillars is used and extension to greater depths using backfill is planned.
Analysis Techniques and Design Methods Rock block analysis See also: 925114 925253 Influence of geological structure on the engineering of underground openings in discontinuous rock masses Goodman, R; Hatzor, Y Proc 6th International Congress International Association of Engineering Geology, Amsterdam, 6-10 August 1990 I/4, P2431-2446. Publ Rotterdam: A A Balkema, 1990
Continuum and discontinuum approaches to modelling rock mass behaviour and the validity of empirical design using rock mass classification methods are briefly examined. Block modelling and the significance of the joint combination (JC), joint pyramid (JP), and key block concepts are introduced. Methods of analysis to find the critical key blocks of an excavation are presented. A case history of tunnelling in jointed crystalline rock is described and the relation between observed block failures and those predicted using field investigation data and block theory is examined. 925254 Block modelling of jointed clifi.s Homand-Etienne, F; Rode, N; Schwartzmann, R Proc International Conference on Mechanics of Jointed and Faulted Rock, Vienna, 18-20 April 1990 P819-825. Publ Rotterdam: A A Balkema, 1990
The chalk cliffs in the Loire valley contain ancient caves and abandoned stone quarries. Falls due to fracturing or collapses of underground voids occur, often associated with particular climatic conditions. The 2D version of the UDEC code has been used to model the cliffs. Rigid or deformable blocks can be considered. Several constitutive laws are available for the joint. Instabilities are compared to those observed, and predicted stresses are compared to those measured with a flat jack along a gallery.
Stress analysis See also: 925337, 925493 925255 Stress nonuniformities in hollow cylinder torsional specimens Wijewickreme, D; Vaid, Y P Geotech Test J VI4, N4, Dee 1991, P349-362
The three dimensional finite element analysis program 3DSLB, using cubical isoparametric elements, has been employed to compute stress nonuniformities across the walls of hollow cylinder torsional shear (HCT) specimens under generalised stress conditions. Nonlinearity of soil behaviour is taken into account. Earlier analyses assuming linear elastic soils are seen to greatly overestimate stress nonuniformities in
© 1992 Pergamon Press Ltd. Reproduction not permitted
A combination inclinometer-deflectometer (CID) has been developed, consisting of two legs of equal length enclosing a horizontal servoaccelerometer (HSA) and a flexure transducer in a waterproof housing. It is combined with a new automated data acquisition and analysis system (ADAAS) to provide a hybrid instrument with enhanced accuracy, reliability, and precision of ground movement measurement. 925250 Machine performance monitoring in surface mines Hendricks, C; Peck J; Scoble, M J Min Engng V44. N3, March 1992, P243-250
Field trials using microprocessor based instruments to monitor operating parameters of rotary blasthole drills and mining shovels are reported. Penetration rate, rotary speed, torque, pulldown pressure, and specific energy have been recorded. Pattern recognition techniques are used to correlate these parameters with variations in rock type and strength. Inferred and logged geology are illustrated. Shovel monitoring allows assessment of how effectively the drilling-derived data have been used in blast design, interpreted in terms of excavator performance related to muckpile characteristics. 925251 Application of a microseismic system at Western Deep Levels van Zyl Brink, A Proc 2nd International Symposium on Rockbursts and Seismicity in Mines, Minneapolis, 8-10 June 1988 P355-361. Publ Rotterdam: A A Balkema, 1990
Microseismic monitoring has been carried out for 20 years at Western Deep Levels, with a system capable of real time prediction of rockburst installed in 1980. Precursory phenomena are described and a number of instances where it was possible to take preventative or mitigative action are presented. The system is also used to monitor fluid injection destressing, monitor failure processes in stabilising pillars, and in study of basic seismological phenomena. 925252 Monitoring of seismicity and measures implemented to alleviate rockburst damage at Kloof A division of Kloof Gold Mining Co. Ltd Waldeck, H G Proc 2nd International Symposium on Rockbursts and Seismicity in Mines, Minneapolis, 8-10 June 1988 P395-400. Publ Rotterdam: A A Balkema, 1990
Rockburst at Kloof A became so severe as the mined-out areas became extensive that stabilising pillars were necessary. A seismic network of 15 geophones was installed in boreholes above and below the Ventersdorp Contact Reef, starting in 1983. Data acquired over 3 years indicate seismic a- and b-
values of 3.45 and 0.89 respectively. Major events are less frequent than in other local mines. These data are used in computer simulations to optimise mining methods. Longwalling with strike stabilising pillars is used and extension to greater depths using backfill is planned.
Analysis Techniques and Design Methods Rock block analysis See also: 925114 925253 Influence of geological structure on the engineering of underground openings in discontinuous rock masses Goodman, R; Hatzor, Y Proc 6th International Congress International Association of Engineering Geology, Amsterdam, 6-10 August 1990 I/4, P2431-2446. Publ Rotterdam: A A Balkema, 1990
Continuum and discontinuum approaches to modelling rock mass behaviour and the validity of empirical design using rock mass classification methods are briefly examined. Block modelling and the significance of the joint combination (JC), joint pyramid (JP), and key block concepts are introduced. Methods of analysis to find the critical key blocks of an excavation are presented. A case history of tunnelling in jointed crystalline rock is described and the relation between observed block failures and those predicted using field investigation data and block theory is examined. 925254 Block modelling of jointed clifi.s Homand-Etienne, F; Rode, N; Schwartzmann, R Proc International Conference on Mechanics of Jointed and Faulted Rock, Vienna, 18-20 April 1990 P819-825. Publ Rotterdam: A A Balkema, 1990
The chalk cliffs in the Loire valley contain ancient caves and abandoned stone quarries. Falls due to fracturing or collapses of underground voids occur, often associated with particular climatic conditions. The 2D version of the UDEC code has been used to model the cliffs. Rigid or deformable blocks can be considered. Several constitutive laws are available for the joint. Instabilities are compared to those observed, and predicted stresses are compared to those measured with a flat jack along a gallery.
Stress analysis See also: 925337, 925493 925255 Stress nonuniformities in hollow cylinder torsional specimens Wijewickreme, D; Vaid, Y P Geotech Test J VI4, N4, Dee 1991, P349-362
The three dimensional finite element analysis program 3DSLB, using cubical isoparametric elements, has been employed to compute stress nonuniformities across the walls of hollow cylinder torsional shear (HCT) specimens under generalised stress conditions. Nonlinearity of soil behaviour is taken into account. Earlier analyses assuming linear elastic soils are seen to greatly overestimate stress nonuniformities in
© 1992 Pergamon Press Ltd. Reproduction not permitted