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Rock strength and overburden changes due to subsidence over a longwall coal mining operation in Illinois
396A double shell concrete lining was developed. At Slany, two shafts were sunk through porous, fractured sandstone/claystone aquifers at 815-940m depth. Eight sudden gas and rockbursts occurred, the largest filling the shaft with 50m of debris. Analysis of causes is attempted. Loosening blasting 15-20m below shaft bottom to destress the rock and allow gradual gas release proved a successful remedial measure.
916513 Applicability of geophysical borehole measurements for rockburst-relevant evaluation of the surrounding rock (In German) Hees, K D; Huwe, H W Gluckanf-forsclnmgsh V52, N3, June 1991, Pl19-125 The hypothesis is presented that the same factors which are responsible for rockburst-relevant stability differences of individual rock beds (mineral content and diagenesis, facies, depth of overburden) are also responsible for changes in borehole geophysical measurements. Based on this, an attempt is made to correlate borehole logs with burst proneness of coal seams.
916514 Design considerations for subsidence control Karmis, M; Yu, Z; Jarosz, A lnt J Min Geol Engng V8, N4, Dec 1990, P357-368 Procedures for subsidence planning during the mine design stage are presented. The Surface Deformation Prediction System (SDPS) incorporates three different subsidence prediction methods, based on the concepts of the influence function, profile function, and zone area methods. Data from the SDPS are used in the Subsidence Response Modelling Program (SRMP), a large displacement, small strain, nonlinear finite element code,to determine damage levels to surface structures resulting from subsidence. An example is presented of use of the SDPS and SRMP in subsidence design and control.
916515 Theory of the collapsed zone at the front of a coal seam and its effect on translatory rock bursting Lippmann, H int J Num Anal Meth Geomech V15, N5, May 1991, P317331 The case of an idealiscd laterally infinite, homogeneous, isotropic seam between rigid parallel layers of other rock is examined. Using a simplified theory, it is demonstrated that, if the slope of the uniaxial stress strain curve in the post failure region is steep enough, the frontal zone of the coal seam close to a cavity (longwall working, roadway, gallery) may suddenly collapse. This collapse, which has been widely observed in situ, is shown to reduce danger of initiation of and severity of subsequent coal bumps.
916516 Ground movement, strata fracturing and changes in permeability due to deep iongwall mining Holla, L; Buizen, M Int J Rock Meeh Min Sci V28, N2/3, May 1991, P207-217 Strata movement due to longwall retreat mining was studied in the Southern coalfield, near Sydney, Australia. Subsurface deformation was monitored by recording the movements of a series of anchors, installed at various depths in a borehole drilled over a longwall panel. Bulk strata permeability was measured by packer tests before and after mining. Pre-mining and post-mining fractures were compared. Vertical strains in the overburden varied from 0.5-4mm/m. Tensile strains extended from the surface to 112m depth and were less than 0.5mm/m. Increases in permeability and number of fractures were seen, but no correlation was evident between the two.
916517 Experiences in French coal mines in continuing the struggle against dynamic phenomena (In French) Josien, J P; Revalor, R Mines Carrieres (Les Techniques) V73, May 1991, P21-26 Rock, gas, and coal burst occurrences in French underground mines are summarised. For each case the factors responsible for the failure have been studied, geological structures, natural and mining-induced stresses, and nature and behaviour of the overburden. Results are discussed with a view to understanding, prediction, and prevention of outburst. Protective stress relief measures are described.
916518 Rock strength and overburden changes due to subsidence over a longwaH coal mining operation in Imnois Brutcher, D F; Mehnert, B B; Van Roosendaal, D J; Bauer, R A Rock Meclumics Contributions and Challenges: Proc 31st US Symposium, Golden, 18-20 June 1990 P563-570. Publ Rotterdam: A A Balkema, 1990 The overburden above an active longwali coal mine in Illinois was characterised before and after caving of a longwali panel. The 2m seam at depth around 200m is overlain by Pennsylvanian shales and sandstones and 7-8m of giacial drift. A 25m thick argillaceous sandstone aquifer lies towards the top of the bedrock. Borehole and core logging, time domain reflectometry, inspection of piezometers and settlement monuments, and pumping tests in the aquifer were carried out. Development of fracturing, fall and subsequent recovery of water table, ground movement development, and their interactions are discussed.
916519 Parameters for ~edicting deformations due to tunnelling Rowe, R K; Lee, K M Proc 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janciro, 13-18 August 1989 V2, P793-796. Publ Rotterdam: A A Balkema, 1989 The accuracy of finite element calculations of deformation of the ground surface due to tunnelling is dependent on the reliability and appropriateness of the input parameters. The stress path during excavation and lining of the tunnel must be taken into account during selection of design parameters. The importance of effective stress parameters, undrained shear strength, and strength anisotropy is evaluated, and a scheme for determining parameters suitable for use in analysis of tunnelling in soft clay is suggested.
916520 Consolidation settlement due to soft ground tunneling Schmidt, B Proc 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, 13-18 August 1989 V2, P797-800. Publ Rotterdam: A A Balkema, 1989 Shield tunnelling in soft clays generally results in settlement caused by ground loss at the face and into the tail void behind the shield. Theoretical and empirical techniques to calculate these displacements are well known. Greater effects may result from delayed settlements due to consolidation. An analysis is presented to describe this time dependent behaviour, which considers mechanisms of consolidation resulting from pore pressures due to radial plastic displacements, excess face support pressure, and the tunnel acting as a drain.
© 1991 Pergamon Press plc. Reproduction not permitted
916513 Applicability of geophysical borehole measurements for rockburst-relevant evaluation of the surrounding rock (In German) Hees, K D; Huwe, H W Gluckanf-forsclnmgsh V52, N3, June 1991, Pl19-125 The hypothesis is presented that the same factors which are responsible for rockburst-relevant stability differences of individual rock beds (mineral content and diagenesis, facies, depth of overburden) are also responsible for changes in borehole geophysical measurements. Based on this, an attempt is made to correlate borehole logs with burst proneness of coal seams.
916514 Design considerations for subsidence control Karmis, M; Yu, Z; Jarosz, A lnt J Min Geol Engng V8, N4, Dec 1990, P357-368 Procedures for subsidence planning during the mine design stage are presented. The Surface Deformation Prediction System (SDPS) incorporates three different subsidence prediction methods, based on the concepts of the influence function, profile function, and zone area methods. Data from the SDPS are used in the Subsidence Response Modelling Program (SRMP), a large displacement, small strain, nonlinear finite element code,to determine damage levels to surface structures resulting from subsidence. An example is presented of use of the SDPS and SRMP in subsidence design and control.
916515 Theory of the collapsed zone at the front of a coal seam and its effect on translatory rock bursting Lippmann, H int J Num Anal Meth Geomech V15, N5, May 1991, P317331 The case of an idealiscd laterally infinite, homogeneous, isotropic seam between rigid parallel layers of other rock is examined. Using a simplified theory, it is demonstrated that, if the slope of the uniaxial stress strain curve in the post failure region is steep enough, the frontal zone of the coal seam close to a cavity (longwall working, roadway, gallery) may suddenly collapse. This collapse, which has been widely observed in situ, is shown to reduce danger of initiation of and severity of subsequent coal bumps.
916516 Ground movement, strata fracturing and changes in permeability due to deep iongwall mining Holla, L; Buizen, M Int J Rock Meeh Min Sci V28, N2/3, May 1991, P207-217 Strata movement due to longwall retreat mining was studied in the Southern coalfield, near Sydney, Australia. Subsurface deformation was monitored by recording the movements of a series of anchors, installed at various depths in a borehole drilled over a longwall panel. Bulk strata permeability was measured by packer tests before and after mining. Pre-mining and post-mining fractures were compared. Vertical strains in the overburden varied from 0.5-4mm/m. Tensile strains extended from the surface to 112m depth and were less than 0.5mm/m. Increases in permeability and number of fractures were seen, but no correlation was evident between the two.
916517 Experiences in French coal mines in continuing the struggle against dynamic phenomena (In French) Josien, J P; Revalor, R Mines Carrieres (Les Techniques) V73, May 1991, P21-26 Rock, gas, and coal burst occurrences in French underground mines are summarised. For each case the factors responsible for the failure have been studied, geological structures, natural and mining-induced stresses, and nature and behaviour of the overburden. Results are discussed with a view to understanding, prediction, and prevention of outburst. Protective stress relief measures are described.
916518 Rock strength and overburden changes due to subsidence over a longwaH coal mining operation in Imnois Brutcher, D F; Mehnert, B B; Van Roosendaal, D J; Bauer, R A Rock Meclumics Contributions and Challenges: Proc 31st US Symposium, Golden, 18-20 June 1990 P563-570. Publ Rotterdam: A A Balkema, 1990 The overburden above an active longwali coal mine in Illinois was characterised before and after caving of a longwali panel. The 2m seam at depth around 200m is overlain by Pennsylvanian shales and sandstones and 7-8m of giacial drift. A 25m thick argillaceous sandstone aquifer lies towards the top of the bedrock. Borehole and core logging, time domain reflectometry, inspection of piezometers and settlement monuments, and pumping tests in the aquifer were carried out. Development of fracturing, fall and subsequent recovery of water table, ground movement development, and their interactions are discussed.
916519 Parameters for ~edicting deformations due to tunnelling Rowe, R K; Lee, K M Proc 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janciro, 13-18 August 1989 V2, P793-796. Publ Rotterdam: A A Balkema, 1989 The accuracy of finite element calculations of deformation of the ground surface due to tunnelling is dependent on the reliability and appropriateness of the input parameters. The stress path during excavation and lining of the tunnel must be taken into account during selection of design parameters. The importance of effective stress parameters, undrained shear strength, and strength anisotropy is evaluated, and a scheme for determining parameters suitable for use in analysis of tunnelling in soft clay is suggested.
916520 Consolidation settlement due to soft ground tunneling Schmidt, B Proc 12th International Conference on Soil Mechanics and Foundation Engineering, Rio de Janeiro, 13-18 August 1989 V2, P797-800. Publ Rotterdam: A A Balkema, 1989 Shield tunnelling in soft clays generally results in settlement caused by ground loss at the face and into the tail void behind the shield. Theoretical and empirical techniques to calculate these displacements are well known. Greater effects may result from delayed settlements due to consolidation. An analysis is presented to describe this time dependent behaviour, which considers mechanisms of consolidation resulting from pore pressures due to radial plastic displacements, excess face support pressure, and the tunnel acting as a drain.
© 1991 Pergamon Press plc. Reproduction not permitted