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Permeability variation around underground openings in jointed rock masses: a numerical study
220A 914166 Hydro-thermo-mechanical response of a fractured rock block Kelkar, S; Zyvoloski, G Rock Mechanics Contributions and Challenges: Proe 31st US Symposium, Golden, 18-20 June 1990 P337-344. Publ Rotterdam. A .4 Balkema. 1990
914170 Characterizing normal stiffness and hydraulic conductivity of a major shear zone in granite Martin, C D; Davison, C C; Kozak, E T Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P549-556. Publ Rotterdam. A A Balkema. 1990
Through finite element techniques coupled with newly developed techniques for solving nonlinear, coupled algebraic equations at different large time intervals, the simulation of hydrothermal-mechanical processes in fractured rock masses can be performed. The developed mathematical model is capable of simulating three dimensional heat and mass flow. A description of the mathematical model and its applications to problems of nonisothermal fluid injection into pre-existing fractures are presented.
A major shear zone at the Underground Research Laboratory was investigated via a system of 35 boreholes. Hydraulic pressure/displacement measurements were made at varying intervals within the zone. Transmission at large scale is variable, with distinct channels of preferential flow. High transmissivity is associated with zones of low normal stress and normal stiffness, and vice versa. A simple contact model is used to illustrate this variation. Joints within the shear zone and associated extensional joints were characterised using the Barton-Bandis joint model. Results agree well with measured in situ normal stiffness.
914167 Estimates of conducting aperture, fracture porosity and fracture permeability in rock masses Lee, C H; Farmer, I W Rock Mechanics Contributions and Challenges: Proc 31st US Symposium, Golden, 18-20 June 1990 P355-362. Publ Rotterdam: A .4 Balkema, 1990 Permeability in rocks, especially those with no intrinsic porosity, is controlled by the aperture of the joints or fractures in the rock. The width of the aperture is itself dependent on the effective stress acting normal to the plane of the fracture. An investigation to develop methods for estimation of fracture porosity and aperture, and permeability of rock masses is presented. Comparison of the results with the published data is also discussed. 914168 Changes in in situ rock joint flow characteristics caused by mechanical displacement Gertsch, L S Rock Mechanics Contributions and Challenges: Proc 31st US Symposium, Golden, 18-20 June 1990 P363-370. Publ Rotterdam." A A Balkema, 1990 The prediction of in situ rock conductivity needs an understanding of rock mass joints, acting stress field, and the behaviour of joints under load. A series of experiments was conducted insitu, in order to determine the conductivity of the fractured rock mass. The tests were conducted using a 2 cubic metre test block of gneiss drilled out in the floor of a drift. Results of the tests and discussion of the experimental set up are presented. 914169 Measurement of the mechanical and hydraulic properties of rock joints at different scales in the Stripa project Makurat, A; Barton, N; Tunbridge, L; Vik, G Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P541-548. P,tbl Rotterdam: A A Balkema, 1990 The program undertaken by the NGI in phase III of the Stripa Mine project includes small scale joint characterisation using 100ram drill cores and large scale mechanical and hydraulic joint behaviour testing, coupled shear/flow/temperature investigation. Laboratory tests on 200mm drill cores in a NGI biaxial cell and in situ tests in a Im block on a drift floor were used to study stress-closure-flow and stress-dilation-flow. Normal stress levels up to 25MPa and 10MPa were used in the laboratory and field respectively. Back calculations yield conducting apertures as low as 8 microns in the laboratory and apparent zero in the field.
914171 Theoretical and field investigations of fracture hydromechanical response under fluid injection Rutqvist, J; Ljunggren, C; Stephansson, O; Noorishad, J; Tsang, C F Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P557-564. Publ Rotterdam: A A Balkema, 1990 Constant pressure injection tests at pressures up to overburden pressure, constant flowrate tests, and pulse injection tests were carried out in four horizontal fractures in a borehole in a rock mass of crystalline granite and gneiss. In the first two cases, coupled effects of mechanical fracture opening due to increasing hydraulic pressure were evident. The 2D finite element code ROCMAS, which simultaneously solves the mechanical and hydraulic equations, is used in a parallel numeric study of these fractures. The potential of this approach is evident. 914172 Permeability variation around underground openings in jointed rock masses: a numerical study Wei, L; Hudson, J A Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P565-569. Publ Rotterdam." A A Balkema. 1990 Permeability around underground structures is affected by excavation both through damage occurring and through stress redistribution. The latter component is considered with a coupled stress and water flow analysis using 3D finite elements. It simulates water inflow from both joints and the permeable rock matrix. Changes in water table under various conditions are examined. Initial results show a skin of altered permeability around the excavation, but its extent is very different under different conditions. 914173 Hydromechanicai coupling between stress, stiffness, and hydraulic conductivity of rock joints and fractures Zimmerman, R W; Chen, D W; Long, J C S; Cook, N G W Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P571-577. Publ Rotterdam. A A Balkema, 1990 The effect of various statistical parameters of the aperture distribution on the hydromechanical properties of rock joints has been examined. Simulated fractures were created by discretizing the fracture plane into a square array and randomly assigning an aperture to each square according to some statistical law. Mechanical deformation is calculated with a 3D elastostatic boundary element method, while flow is reduced to a 2D Laplace equation, also solved using boundary elements.
i~ 1991 Pergamon Press plc. Reproduction not permitted
914170 Characterizing normal stiffness and hydraulic conductivity of a major shear zone in granite Martin, C D; Davison, C C; Kozak, E T Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P549-556. Publ Rotterdam. A A Balkema. 1990
Through finite element techniques coupled with newly developed techniques for solving nonlinear, coupled algebraic equations at different large time intervals, the simulation of hydrothermal-mechanical processes in fractured rock masses can be performed. The developed mathematical model is capable of simulating three dimensional heat and mass flow. A description of the mathematical model and its applications to problems of nonisothermal fluid injection into pre-existing fractures are presented.
A major shear zone at the Underground Research Laboratory was investigated via a system of 35 boreholes. Hydraulic pressure/displacement measurements were made at varying intervals within the zone. Transmission at large scale is variable, with distinct channels of preferential flow. High transmissivity is associated with zones of low normal stress and normal stiffness, and vice versa. A simple contact model is used to illustrate this variation. Joints within the shear zone and associated extensional joints were characterised using the Barton-Bandis joint model. Results agree well with measured in situ normal stiffness.
914167 Estimates of conducting aperture, fracture porosity and fracture permeability in rock masses Lee, C H; Farmer, I W Rock Mechanics Contributions and Challenges: Proc 31st US Symposium, Golden, 18-20 June 1990 P355-362. Publ Rotterdam: A .4 Balkema, 1990 Permeability in rocks, especially those with no intrinsic porosity, is controlled by the aperture of the joints or fractures in the rock. The width of the aperture is itself dependent on the effective stress acting normal to the plane of the fracture. An investigation to develop methods for estimation of fracture porosity and aperture, and permeability of rock masses is presented. Comparison of the results with the published data is also discussed. 914168 Changes in in situ rock joint flow characteristics caused by mechanical displacement Gertsch, L S Rock Mechanics Contributions and Challenges: Proc 31st US Symposium, Golden, 18-20 June 1990 P363-370. Publ Rotterdam." A A Balkema, 1990 The prediction of in situ rock conductivity needs an understanding of rock mass joints, acting stress field, and the behaviour of joints under load. A series of experiments was conducted insitu, in order to determine the conductivity of the fractured rock mass. The tests were conducted using a 2 cubic metre test block of gneiss drilled out in the floor of a drift. Results of the tests and discussion of the experimental set up are presented. 914169 Measurement of the mechanical and hydraulic properties of rock joints at different scales in the Stripa project Makurat, A; Barton, N; Tunbridge, L; Vik, G Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P541-548. P,tbl Rotterdam: A A Balkema, 1990 The program undertaken by the NGI in phase III of the Stripa Mine project includes small scale joint characterisation using 100ram drill cores and large scale mechanical and hydraulic joint behaviour testing, coupled shear/flow/temperature investigation. Laboratory tests on 200mm drill cores in a NGI biaxial cell and in situ tests in a Im block on a drift floor were used to study stress-closure-flow and stress-dilation-flow. Normal stress levels up to 25MPa and 10MPa were used in the laboratory and field respectively. Back calculations yield conducting apertures as low as 8 microns in the laboratory and apparent zero in the field.
914171 Theoretical and field investigations of fracture hydromechanical response under fluid injection Rutqvist, J; Ljunggren, C; Stephansson, O; Noorishad, J; Tsang, C F Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P557-564. Publ Rotterdam: A A Balkema, 1990 Constant pressure injection tests at pressures up to overburden pressure, constant flowrate tests, and pulse injection tests were carried out in four horizontal fractures in a borehole in a rock mass of crystalline granite and gneiss. In the first two cases, coupled effects of mechanical fracture opening due to increasing hydraulic pressure were evident. The 2D finite element code ROCMAS, which simultaneously solves the mechanical and hydraulic equations, is used in a parallel numeric study of these fractures. The potential of this approach is evident. 914172 Permeability variation around underground openings in jointed rock masses: a numerical study Wei, L; Hudson, J A Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P565-569. Publ Rotterdam." A A Balkema. 1990 Permeability around underground structures is affected by excavation both through damage occurring and through stress redistribution. The latter component is considered with a coupled stress and water flow analysis using 3D finite elements. It simulates water inflow from both joints and the permeable rock matrix. Changes in water table under various conditions are examined. Initial results show a skin of altered permeability around the excavation, but its extent is very different under different conditions. 914173 Hydromechanicai coupling between stress, stiffness, and hydraulic conductivity of rock joints and fractures Zimmerman, R W; Chen, D W; Long, J C S; Cook, N G W Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P571-577. Publ Rotterdam. A A Balkema, 1990 The effect of various statistical parameters of the aperture distribution on the hydromechanical properties of rock joints has been examined. Simulated fractures were created by discretizing the fracture plane into a square array and randomly assigning an aperture to each square according to some statistical law. Mechanical deformation is calculated with a 3D elastostatic boundary element method, while flow is reduced to a 2D Laplace equation, also solved using boundary elements.
i~ 1991 Pergamon Press plc. Reproduction not permitted