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Elastodynamic simulation of mining
68A Stabilising pillars, installed to reduce faceburst, have themselves become the source of large seismic events in areas of very low stress. This has prompted review of current mining practices and effectiveness of the applied remedial measures. 931515 Subsidence-induced well failure Bruno, M S S P E Drilling Engng V7, N2, June 1992, P148-152 Depletion of petroleum or gas resources may lead to reservoir compaction and subsidence, which in turn may cause well casing damage. An idealised, simple finite element analysis of depletion-induced subsidence is illustrated. The resulting movement-induced damage to the well casing by compression and buckling, buckling, shear, and bending mechanisms is analysed. Overburden shear failure or subsidence-induced fault movement may also occur and these abrupt ground movements will cause wellbore damage.
931516 Numerical prediction of strata deformation associated with Iongwail mining Summers, J W; Jeffery, R I Trans Inst Min Metall (Sect A Min lnd) VIOl, Jan-April 1992, PA63-A74 A finite element numerical model to predict strain and displacement resulting from longwall mining is presented. Anisotropy and lamination in the rock mass are included. The caved waste is represented as a compressible granular fill material. Calibration of the model, in the absence of suitable laboratory data to describe pre- and post-yield behaviour of the rock materials, required detailed comparisons of model predictions and field behaviour. The model is applied to evaluate the risk of waterflow into longwall faces for two U K collieries with different hydrological settings. 931517 Fluid injection for rockburst control in deep mining Board, M; Rorke, T; Williams, G; Gay, N Proc 33rd US Symposium on Rock Mechanics, Santa Fe, 3-5 June 1992 PIll-120. Publ Rotterdam." A A Balkema, 1992 Shear-type rockburst events with violent energy release cause many problems in deep mines. Induced seismicity along fault surfaces has been observed during fluid injection in oilfields and in mine flooding, the postulated mechanism being slip resulting from reduction of normal stress across the fault. Injection experiments have been carried out in the Buffelsfontein gold mine, to see if slip on faults can be induced at a pre-determined time, with small-scale seismic events replacing damaging ones.
Influence of dynamic loads 931518 Quantitative evaluation of seismic potential during the extraction of the Scott Shaft pillar, Stilfontein Gold Mine Syratt, P P Proc I S R M International Symposium on Static and Dynamic Considerations in Rock Engineering, Swaziland, 10-12 September 1990 P325-327. Publ Rotterdam: A A Balkema, 1990 The Scott Shaft pillar is bisected by a seismically active dyke. Seismic potential has been estimated at each stage of the mining sequence on the basis of its relation to total volume closure
and evaluated using the MINS1M-D code. The seismic hazard is the difference between estimated seismic potential and observed seismicity. Modelling of seismic potential appears to correlate well with observed trends at the mine, implying that with further verification and calibration, the technique described could be used routinely to quantify seismic hazards.
931519 Elastodynamic simulation of mining Tian, Y; Loken, M C; Crouch, S L Proc I S R M International Symposium on Static and Dynamic Considerations in Rock Engineering, Swaziland, 10-12 September 1990 P329-337. Publ Rotterdam: ,4 A Balkema, 1990 A combination of two boundary element methods is used to simulate dynamic effects of mining in an infinite, homogeneous, isotropic, linearly elastic rock mass. A static method is first used to compute the stress field around an initially mined stope and the dynamic method of Crouch and Tian (1988) used to simulate blasting by applying dynamic incremental tractions to the newly excavated boundary. The sum of the static and dynamic results gives the total elastodynamic response at any given spatial location and time.
Subjects Peripheral to Geomechanics 931520 Liquid conduction tests for geomembranes Ozsu, E; Acar, Y B Geotext Geomem VII, N3, 1992, P291-318 Geomembranes are widely employed in liners for waste containment. Limited data are at present available on wasteleachate-membrane-liner compatibility. An apparatus and a method are presented which allow determination of a quantitative index parameter for liquid conduction through geomembranes. Selected membranes and chemicals have been tested to assess effects of change in type or concentration of the permeant on the hydraulic properties of the geomembranes.
Snow and ice mechanics See also: 931280
931521 Notch sensitivity and brittleness in fracture testing of $2 columnar freshwater ice Dempsey, J P; Wei, Y; Defranco, S J lnt J Fract V53, N2, Jan 1992, P101-120 Four-point- and three-point-bend loading tests were carried out to examine the fracture toughness of $2 columnar freshwater ice. Crack lengths were varied for one specific crack orientation and one grain size. Specimen size effects were also examined. The aim is to develop a fracture toughness test for ice which satisfies small scale yielding requirements and provides toughness values independent of specimen size and geometry. These results suggest that specimens used in testing $2 ice to date have been largely sub-size.
© 1993 Pergamon Press Ltd. Reproduction not permitted
931516 Numerical prediction of strata deformation associated with Iongwail mining Summers, J W; Jeffery, R I Trans Inst Min Metall (Sect A Min lnd) VIOl, Jan-April 1992, PA63-A74 A finite element numerical model to predict strain and displacement resulting from longwall mining is presented. Anisotropy and lamination in the rock mass are included. The caved waste is represented as a compressible granular fill material. Calibration of the model, in the absence of suitable laboratory data to describe pre- and post-yield behaviour of the rock materials, required detailed comparisons of model predictions and field behaviour. The model is applied to evaluate the risk of waterflow into longwall faces for two U K collieries with different hydrological settings. 931517 Fluid injection for rockburst control in deep mining Board, M; Rorke, T; Williams, G; Gay, N Proc 33rd US Symposium on Rock Mechanics, Santa Fe, 3-5 June 1992 PIll-120. Publ Rotterdam." A A Balkema, 1992 Shear-type rockburst events with violent energy release cause many problems in deep mines. Induced seismicity along fault surfaces has been observed during fluid injection in oilfields and in mine flooding, the postulated mechanism being slip resulting from reduction of normal stress across the fault. Injection experiments have been carried out in the Buffelsfontein gold mine, to see if slip on faults can be induced at a pre-determined time, with small-scale seismic events replacing damaging ones.
Influence of dynamic loads 931518 Quantitative evaluation of seismic potential during the extraction of the Scott Shaft pillar, Stilfontein Gold Mine Syratt, P P Proc I S R M International Symposium on Static and Dynamic Considerations in Rock Engineering, Swaziland, 10-12 September 1990 P325-327. Publ Rotterdam: A A Balkema, 1990 The Scott Shaft pillar is bisected by a seismically active dyke. Seismic potential has been estimated at each stage of the mining sequence on the basis of its relation to total volume closure
and evaluated using the MINS1M-D code. The seismic hazard is the difference between estimated seismic potential and observed seismicity. Modelling of seismic potential appears to correlate well with observed trends at the mine, implying that with further verification and calibration, the technique described could be used routinely to quantify seismic hazards.
931519 Elastodynamic simulation of mining Tian, Y; Loken, M C; Crouch, S L Proc I S R M International Symposium on Static and Dynamic Considerations in Rock Engineering, Swaziland, 10-12 September 1990 P329-337. Publ Rotterdam: ,4 A Balkema, 1990 A combination of two boundary element methods is used to simulate dynamic effects of mining in an infinite, homogeneous, isotropic, linearly elastic rock mass. A static method is first used to compute the stress field around an initially mined stope and the dynamic method of Crouch and Tian (1988) used to simulate blasting by applying dynamic incremental tractions to the newly excavated boundary. The sum of the static and dynamic results gives the total elastodynamic response at any given spatial location and time.
Subjects Peripheral to Geomechanics 931520 Liquid conduction tests for geomembranes Ozsu, E; Acar, Y B Geotext Geomem VII, N3, 1992, P291-318 Geomembranes are widely employed in liners for waste containment. Limited data are at present available on wasteleachate-membrane-liner compatibility. An apparatus and a method are presented which allow determination of a quantitative index parameter for liquid conduction through geomembranes. Selected membranes and chemicals have been tested to assess effects of change in type or concentration of the permeant on the hydraulic properties of the geomembranes.
Snow and ice mechanics See also: 931280
931521 Notch sensitivity and brittleness in fracture testing of $2 columnar freshwater ice Dempsey, J P; Wei, Y; Defranco, S J lnt J Fract V53, N2, Jan 1992, P101-120 Four-point- and three-point-bend loading tests were carried out to examine the fracture toughness of $2 columnar freshwater ice. Crack lengths were varied for one specific crack orientation and one grain size. Specimen size effects were also examined. The aim is to develop a fracture toughness test for ice which satisfies small scale yielding requirements and provides toughness values independent of specimen size and geometry. These results suggest that specimens used in testing $2 ice to date have been largely sub-size.
© 1993 Pergamon Press Ltd. Reproduction not permitted