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Periodic patterns of granular flow through a plane container
74A from laboratory' triaxial, vane, and Tor',ane tests, and in situ piezocone penetrometer tests. In situ vane strength is in good agreement with that from UU triaxia[ tests. Rate of strain softening appears dependent on plasticity, and minimum rotations to obtain accurate reaidual strengths are proposed. The evaluation of Ko from triaxial and in situ vane tests is considered. 912089 Determination of hyperbolic soil model parameters for sand using a multiaxial device Rauch, A F; Sargand. S M; Hazen. G A
Proc 3rd International Symposium on Numer&al Models in Geomechanics (NUAIOG i!1), N~agara Falls, 8-11 l~Iay 1989 P272-280. Publ London." Elsevier Applied Science. 1989 A medium dense sand was tested along a number of stress paths in a cubical triaxial apparatus. Soil parameters derived were input into the hyperbolic model of Duncan et al (1980). Results from conventional triaxial compression tests compared well with those from a standard triaxial apparatus. Multiaxial tests were carried out along other stress paths (reduced triaxial compression and extension, triaxial compression and extension, simple shear, proportional loading, hydrostatic pressure) and the sets of parameters obtained are tested against laboratory data. 912090 Limit load in steady 3-D plastic flow around obstacles Lin, M: Drescher. A
Proc 3rd International Symposium on Numer&ai Models" in Geomechanics (NUMOG !11), Niagara Falls. 8-11 May 1989 P293-304. Puhl London: Elsevier Applied Science, 1989 A proposed approach for solving limit load problems in three dimensional or pseudo-three dimensional steady plastic flow is presented. The flowing material is rigid-plastic, either perfectly or isotropically strain hardening'softening. Approximate limit load, identified with force exerted on the obstacle, is obtained using an energy method. An example illustrates the flow of an incompressible soil or broken ice around a wedge shaped obstacle. 912091 Periodic patterns of granular flow through a plane container Michalowski. R L
Proc 3rd International Symposium on Numerical Models in Geomechanics (NUMOG I!i), Niagara Falls, 8-11 May 1989 P305-310. P,¢bl London: Elsevier Applied Science, 1989 Flow of bulk materials through containers often causes cyclic perturbations in the loads exerted on the container walls. The observed velocity field i~. not constant, with regions of low velocity gradient separated by narrow zones of very high velocity gradient (shear bands). This strain Iocalisation phenomenon is incorporated into the framework of the kinematical approach of limit analysis. Using the hypothesis of minimum material effort, it is possible to predict the cyclic fluctuation of velocity field, and the corresponding perturbations of wall pressure. 912092 Numerical modelling of the development of shear bands in geomechanics Wan, R G: Chan, D H; Morgenstern. N R
Proc 3rd International Symposium on Numerical Models in Geomechanics (NU~WOG III), Niagara Falls, 8-11 May 1989 P319-329. Publ London: Elsevier Applied Science, 1989 Strain localisation in soils is analysed. The analysis is based on the assumption that localisation occurs as a result of constitutive instability characterised by bifurcation theory, which is
expanded into well defined stress boundary condiuons with material behaviour governed by simple yield criteria. Localised deformation is modelled using the principle of virtual ~vork to account for energy dissipation. A numerical application in finite element analysis of an embankment is presented, and improvements in modelling strain distributions when compared to conventional finite element analysis are discussed.
Fracture processes 912093 Alignment of near-surface inclusions and appropriate crack geometries for geothermal hot-dry-rock experiments Crampin, S
Geophys Prospect V38. N6. Aug 1990, P621-631 Shear wave splitting indicates most rocks in the upper crust are pervaded by fluid filled, stress-aligned inclusions, EDAcracks. These will align perpendicular to minimum compressive stress. Where overburden stress is high, typical EDAcracks will be aligned vertically, striking parallel to or subparallel to direction of maximum compression. At the free surface, vertical stress tends to zero and cracks tend to the horizontal, swinging through 90 deg as the surface is approached. Since cracks and stress are important to rock mass behaviour, data must be used only in the depth horizon for which they are appropriate.
912094 Propagation of fluid-driven fractures in jointed rock. Part I Development and validation of methods of analysis Hcuze, F E: Shaffcr, R J: Ingraffea, A R: Nilson, R H
lnt J Rock Mech Min Sci V27. N4. Aug 1990. P243-254 An analysis is presented to describe the propagation of induced fluid driven fractures in rock masses containing preexisting discontinuities. [t is based on a two dimensional model with coupled solid-, fluid-, and fracture mechanics. The initial F E F F L A P model (Finite Element Fracture and Flow Analysis Program) '.,,as tested against analytical solutions and laboratory experiments. A time dependent version was developed by replacing the original flow model with one based on the FAST fluid mechanics module. This model was again validated against laboratory data.
912095 Propagation of fluid-driven fractures in jointed rock. Part 2 Physical tests on blocks with an interface or lens Blair, S C; Thorpe, R K; Heuze, F E
Int J Rock Mecll Min Sci V27. N4, Aug 1990, P255-268 Numerical models to describe hydrofracturing of jointed rocks were developed earlier (ibid, V27, N4, P243-254). Complementary experimental tests are described. The first series (interface tests) was performed concurrently with development of a steady state coupled fracture and flow model. Hydrostone blocks under biaxial loading were used, and propagation of fractures across interfaces examined. A further series (lens tests) used hydrostone blocks with embedded sandstone lenses, under triaxial stress. These were fractured with single wing fluid driven cracks, and crack front and fluid pressure followed as a function of time. Results validated the time dependent numerical models.
(' 1991 Pergamon Press pie. Reproduction not permitted
Proc 3rd International Symposium on Numer&al Models in Geomechanics (NUAIOG i!1), N~agara Falls, 8-11 l~Iay 1989 P272-280. Publ London." Elsevier Applied Science. 1989 A medium dense sand was tested along a number of stress paths in a cubical triaxial apparatus. Soil parameters derived were input into the hyperbolic model of Duncan et al (1980). Results from conventional triaxial compression tests compared well with those from a standard triaxial apparatus. Multiaxial tests were carried out along other stress paths (reduced triaxial compression and extension, triaxial compression and extension, simple shear, proportional loading, hydrostatic pressure) and the sets of parameters obtained are tested against laboratory data. 912090 Limit load in steady 3-D plastic flow around obstacles Lin, M: Drescher. A
Proc 3rd International Symposium on Numer&ai Models" in Geomechanics (NUMOG !11), Niagara Falls. 8-11 May 1989 P293-304. Puhl London: Elsevier Applied Science, 1989 A proposed approach for solving limit load problems in three dimensional or pseudo-three dimensional steady plastic flow is presented. The flowing material is rigid-plastic, either perfectly or isotropically strain hardening'softening. Approximate limit load, identified with force exerted on the obstacle, is obtained using an energy method. An example illustrates the flow of an incompressible soil or broken ice around a wedge shaped obstacle. 912091 Periodic patterns of granular flow through a plane container Michalowski. R L
Proc 3rd International Symposium on Numerical Models in Geomechanics (NUMOG I!i), Niagara Falls, 8-11 May 1989 P305-310. P,¢bl London: Elsevier Applied Science, 1989 Flow of bulk materials through containers often causes cyclic perturbations in the loads exerted on the container walls. The observed velocity field i~. not constant, with regions of low velocity gradient separated by narrow zones of very high velocity gradient (shear bands). This strain Iocalisation phenomenon is incorporated into the framework of the kinematical approach of limit analysis. Using the hypothesis of minimum material effort, it is possible to predict the cyclic fluctuation of velocity field, and the corresponding perturbations of wall pressure. 912092 Numerical modelling of the development of shear bands in geomechanics Wan, R G: Chan, D H; Morgenstern. N R
Proc 3rd International Symposium on Numerical Models in Geomechanics (NU~WOG III), Niagara Falls, 8-11 May 1989 P319-329. Publ London: Elsevier Applied Science, 1989 Strain localisation in soils is analysed. The analysis is based on the assumption that localisation occurs as a result of constitutive instability characterised by bifurcation theory, which is
expanded into well defined stress boundary condiuons with material behaviour governed by simple yield criteria. Localised deformation is modelled using the principle of virtual ~vork to account for energy dissipation. A numerical application in finite element analysis of an embankment is presented, and improvements in modelling strain distributions when compared to conventional finite element analysis are discussed.
Fracture processes 912093 Alignment of near-surface inclusions and appropriate crack geometries for geothermal hot-dry-rock experiments Crampin, S
Geophys Prospect V38. N6. Aug 1990, P621-631 Shear wave splitting indicates most rocks in the upper crust are pervaded by fluid filled, stress-aligned inclusions, EDAcracks. These will align perpendicular to minimum compressive stress. Where overburden stress is high, typical EDAcracks will be aligned vertically, striking parallel to or subparallel to direction of maximum compression. At the free surface, vertical stress tends to zero and cracks tend to the horizontal, swinging through 90 deg as the surface is approached. Since cracks and stress are important to rock mass behaviour, data must be used only in the depth horizon for which they are appropriate.
912094 Propagation of fluid-driven fractures in jointed rock. Part I Development and validation of methods of analysis Hcuze, F E: Shaffcr, R J: Ingraffea, A R: Nilson, R H
lnt J Rock Mech Min Sci V27. N4. Aug 1990. P243-254 An analysis is presented to describe the propagation of induced fluid driven fractures in rock masses containing preexisting discontinuities. [t is based on a two dimensional model with coupled solid-, fluid-, and fracture mechanics. The initial F E F F L A P model (Finite Element Fracture and Flow Analysis Program) '.,,as tested against analytical solutions and laboratory experiments. A time dependent version was developed by replacing the original flow model with one based on the FAST fluid mechanics module. This model was again validated against laboratory data.
912095 Propagation of fluid-driven fractures in jointed rock. Part 2 Physical tests on blocks with an interface or lens Blair, S C; Thorpe, R K; Heuze, F E
Int J Rock Mecll Min Sci V27. N4, Aug 1990, P255-268 Numerical models to describe hydrofracturing of jointed rocks were developed earlier (ibid, V27, N4, P243-254). Complementary experimental tests are described. The first series (interface tests) was performed concurrently with development of a steady state coupled fracture and flow model. Hydrostone blocks under biaxial loading were used, and propagation of fractures across interfaces examined. A further series (lens tests) used hydrostone blocks with embedded sandstone lenses, under triaxial stress. These were fractured with single wing fluid driven cracks, and crack front and fluid pressure followed as a function of time. Results validated the time dependent numerical models.
(' 1991 Pergamon Press pie. Reproduction not permitted