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Endochronic modeling of coupled volumetric-deviatoric behaviour of porous and granular materials
233A
Rock block analysis 885248 Stability analysis of concrete gravity dams on blocky rock foundations Grenoble, A; Amadei, B; Illangasekare, T H Proc CARE 88 (Conference on Applied Rock Engineering), Newcastle, 6-8 January 1988 P71-81. Publ London: IMM, 1988 Evaluating the stability of structures on blocky ground is complex, since pore water pressure distribution is governed by the orientation and permeability of the joints. A method is presented using 3-d finite element analysis to calculate seepage, and Goodman and Shi's key block theory for stability analysis. Simple examples illustrate use of the procedure. A technique to incorporate the influence of stress-induced changes on joint aperture is discussed. 885249 Predicting the number of dimensions of key blocks of an excavation using Block Theory and joint analysis Lap-yan Chan; Goodman, R E Proc 28th US Symposium on Rock Mechanics, Tucson, 29 June-I July 1987 P81-87. Publ Rotterdam: A A Balkema, 1987 Development of key block theory is briefly outlined. A Monte Carlo simulation theory for predicting the support reqatrements for an excavation is presented. The major input parameters are excavation geometry, joint set properties, key block codes and stability, and the volume in which joint discs are generated. A case study examines the effects of tunnel width, mean joint density, and mean trace length for a horizontal tunnel in a rock mass cut by three joint sets.
Stress analysis See also: 885110, 885150, 885395 885250 Capped plasticity model applied to Boston blue clay McCarron, W O; Chen, W F Can Geotech J 1/24, N4, Nov 1987, P630-644 Computed responses for Boston blue clay are compared to laboratory stress paths and boundary value problems involving construction of an embankment. Simplifications in the model result in difficulties in its calibration for general stress paths. Chief limitations are the use of a circular deviatoric plane and the assumption of symmetry about the hydrostatic axis. Provided its limitations are realised, the model performs well. 885251 Plasticity computations using the Mohr-Coulomb yield criterion Crisfield, M A Engng Comput V4, N4, Dec 1987, P300-308 The derivation and application of a number of algorithms for implementing the Mohr-Coulomb criterion in nonlinear finite element programs is described. Emphasis is given to the backward-Euler scheme which can be used to give a simple and efficient algorithm. A range of methods is used to derive the tangent modular matrix. Calculations for the cases of passive pressure for vertical and inclined retaining walls, and for a strip footing are illustrated.
885252 Viscoplastic model for soft rock Reed, M B Engng Comput 1/5, NI, March 1988. P65-70 A model to represent the main features of soft or brittle rock is presented. Yield surface is based on Mohr-Coulomb or HockBrown criteria, and a simple small-dilation flow rule allows the implicit algorithm of elasto-viscoplasticity to be used. Elasticbrittle failure behaviour with stress discontinuities across the interface between intact and failed rock is modelled. Jointing and lamination can be taken into account. An example of its use to determine displacements and stresses around a tunnel is presented. 885253 Axisymmetric fundamental solutions for a completely saturated porous elastic solid Puswewala, U G A; Rajapakse, R K N D Int J Engng Sci V26, N5, 1988, P419-436 Elastic deformations of saturated rocks or soils are of engineering importance. Fundamental solutions are derived in order to apply the boundary integral equation to poroelastic infinite and semi-infinite materials. Solutions considered are Laplace or time domain solutions for computational efficiency. Numerical results for vertical displacements and pore fluid pressure are presented for uniform and non-uniform buried patch loads acting in a vertical direction. 885254 Influence of out-of-plane stress on a plane strain problem in rock mechanics Reed, M B lnt J Num Anal Meth Geomech VI2, N2, March-April 1988, P173-181 Axisymmetric cavity expansion of a brittle Mohr-Coulomb rock in a hydrostatic stress field is examined. Previous plane strain displacement solutions have assumed out-of-plane stress remains the intermediate principal stress at all points. A displacement solution using a variable dilation plastic flow rule is given for the case when this assumption breaks down. Results are compared with previous solutions for specific problems. A significant difference is only found for problems with a large strength drop on yield. 885255 Unconditionally stable staggered solution procedures for soilpore fluid interaction problems Zienkiewicz, O C; Paul, D K; Chan, A H C lnt J Num Meth Engng V26, N5, May 1988, P1039-1055 A simple modified unconditionally stable implicit-implicit staggered approach is presented to describe soil-pore fluid interaction. It is simpler than the alternative proposed by Park. Soil-pore fluid interaction during earthquake and consolidation loading is examined, and numerical examples of 1 and 2-dimensional saturated poroelastic media are illustrated. 885256 Endochronic modeling of coupled volumetric-deviatoric behaviour of porous and granular materials Wu, H C; Aboutorabi, M R lnt J Plasticity V4, N2, 1988, P163-181 Constitutive behaviour of materials such as soils, rocks, concrete, or powders has been analysed using endochronic plasticity theory. Coupled volumetric-deviatoric behaviour, including volumetric deformation enhanced by shear loading
© 1988 Pergamon Press pie. Reproduction not permitted
234A and the enhancement of deviatoric deformation due to hydrostatic loads, is examined. The theory is applied to available results from concrete, and this application demonstrates a reasonably wide range of applicability of the model. 885257 Microcrack model of dilatancy in brittle materials Nemat-Nasser, S; Obata, M J Appl Mech (Trans ASME Set E) V5, N1, March 1988, P24-35 Nonlinear constitutive relations are developed for a model incorporating preexisting flaws with frictional and cohesive resistance, and which includes nucleation and growth of tension cracks at these flaws during deformation. A dilute distribution of preexisting flaws is assumed, and equations developed for loading and unloading, which include hysteresis, dilatancy and other characteristics observed in rocks and brittle materials. Illustrated examples are compared to experimental observations. 885258 Constitutive model for sands and clays evaluating principal stress rotation Matsuoka, H; Sakakibara, K Soils Found V27, N4, Dec 1987, P73-88 A constitutive equation is developed by which general strain increments are directly related to general stress increments. To evaluate the effects of principal stress rotation, experiments were carried out in a two dimensional general stress apparatus using a stack of aluminium rods to simulate soil particles. Test results agree well with predictions based on the model. Simple shear and liquefaction with principal stress rotation are analysed with the model. The model is extended to three dimensions using the superposition of the two dimensional principal strain increments. 885259 Modelling of non-linear behaviour of fractured seams in deep gold mines Brummer, R K Proc APCOM 87, Johannesburg, 19-23 October 1987 VI, P21-32. Publ Johannesburg: SAIMM, 1987 A simplified two dimensional plane strain model of tabular excavation in a brittle rock mass under high stress is presented. Relatively straightforward assumptions based on underground observations of fracturing and deformation at the stope base plus laboratory testing are made. The elastic rockmass remote from the reef is modelled using boundary elements, the reef rockmass using a linear string of yielding elements. Predicted and observed convergence and stresses during extraction of a remnant pillar are in good agreement. 88526O Three dimensional stress analysis: a practical planning tool for mining problems Diering, J A C; Stacey, T g Proc APCOM 87, Johannesburg, 19-23 October 1987 VI, P33-42. Publ Johannesburg: SAIMM, 1987 Mining involves excavations of finite size in infinite or semiinfinite rock masses. Three dimensional stress analysis using the boundary element method is discussed, the various types of boundary element considered, and the non conforming quadrilateral element, developed specifically for mining problems, introduced. Illustrated examples examine the interaction of excavations at great depth, open stope mining layout, and design of a drawpoint system for block caving.
885261 Three dimensional stress analysis of block caving mining layouts Esterhuizen, G S Proc APCOM 87, Johannesburg, 19-23 October 1987 VI. P43-48. Publ Johannesburg: SAIMM, 1987 Block caving is used to mine large orebodies in weak rock types. Development of extraction drives and drawpoints beneath the caving block further weakens the rock mass. Three dimensional boundary element analysis is used to examine the effect of alternative extraction level layouts on stress fields. Results indicate that the use of lateral pillars between drawpoints improves stability of extraction pillars and extraction drives. Further minor improvements are made by offsetting the lateral pillars.
Design methods 885262 Analysis of deep-level mine design problems using the MINSIM-D boundary element program Napier, J A L; Stephansen, S J Proe APCOM 87, Johannesburg, 19-23 October 1987 VI, P319. Publ Johannesburg: SAIMM, 1987 The theoretical background and novel solution procedures used in MINSIM-D are described. It can handle interaction from mining on multiple reefs, slip on weak fault planes, effect of backfill placement, and incremental mining sequences. -DIGITIZER and FRONT-END routines have been written to assist capture of mining outlines and general problem specifications. Suitable applications and further extensions of MINSIM-D are illustrated, and an example of its use presented. 885263 Identification of geometric characteristics of inhomogeneous rock masses by AIC method Ohnishi, Y; Higashide, A Proc International Symposium on Engineering in Complex Rock Formations, Beijing, 3-7 November 1986 1'945-950. Publ Beijing: Science Press, 1986 The basic concepts for estimating the geometric characteristics and material properties of a zoned rock mass from a limited number of field measurements are described. Elastic parameters are calculated using an optimisation procedure. The concepts of AIC (Akaike's Information Criterion) and MAICE (Minimum theoretical AIC Estimate) are introduced for optimum estimation of the boundaries of zones in inhomogeneous structures for constructing a geometrically suitable model.
Rock Breakage and Excavation Drilling 885264 Horizontal directional drilling Szczupak, J R Geodriiling N48, Feb 1988. PI 1-14 Horizontal directional drilling techniques are widely used to underpass obstacles when laying pipes or cables, on cost, environmental and protection grounds. The drilling procedure from initial set up, through pilot hole drilling and reaming, to
© 1988 Pergamon Press plc. Reproduction not permitted
Rock block analysis 885248 Stability analysis of concrete gravity dams on blocky rock foundations Grenoble, A; Amadei, B; Illangasekare, T H Proc CARE 88 (Conference on Applied Rock Engineering), Newcastle, 6-8 January 1988 P71-81. Publ London: IMM, 1988 Evaluating the stability of structures on blocky ground is complex, since pore water pressure distribution is governed by the orientation and permeability of the joints. A method is presented using 3-d finite element analysis to calculate seepage, and Goodman and Shi's key block theory for stability analysis. Simple examples illustrate use of the procedure. A technique to incorporate the influence of stress-induced changes on joint aperture is discussed. 885249 Predicting the number of dimensions of key blocks of an excavation using Block Theory and joint analysis Lap-yan Chan; Goodman, R E Proc 28th US Symposium on Rock Mechanics, Tucson, 29 June-I July 1987 P81-87. Publ Rotterdam: A A Balkema, 1987 Development of key block theory is briefly outlined. A Monte Carlo simulation theory for predicting the support reqatrements for an excavation is presented. The major input parameters are excavation geometry, joint set properties, key block codes and stability, and the volume in which joint discs are generated. A case study examines the effects of tunnel width, mean joint density, and mean trace length for a horizontal tunnel in a rock mass cut by three joint sets.
Stress analysis See also: 885110, 885150, 885395 885250 Capped plasticity model applied to Boston blue clay McCarron, W O; Chen, W F Can Geotech J 1/24, N4, Nov 1987, P630-644 Computed responses for Boston blue clay are compared to laboratory stress paths and boundary value problems involving construction of an embankment. Simplifications in the model result in difficulties in its calibration for general stress paths. Chief limitations are the use of a circular deviatoric plane and the assumption of symmetry about the hydrostatic axis. Provided its limitations are realised, the model performs well. 885251 Plasticity computations using the Mohr-Coulomb yield criterion Crisfield, M A Engng Comput V4, N4, Dec 1987, P300-308 The derivation and application of a number of algorithms for implementing the Mohr-Coulomb criterion in nonlinear finite element programs is described. Emphasis is given to the backward-Euler scheme which can be used to give a simple and efficient algorithm. A range of methods is used to derive the tangent modular matrix. Calculations for the cases of passive pressure for vertical and inclined retaining walls, and for a strip footing are illustrated.
885252 Viscoplastic model for soft rock Reed, M B Engng Comput 1/5, NI, March 1988. P65-70 A model to represent the main features of soft or brittle rock is presented. Yield surface is based on Mohr-Coulomb or HockBrown criteria, and a simple small-dilation flow rule allows the implicit algorithm of elasto-viscoplasticity to be used. Elasticbrittle failure behaviour with stress discontinuities across the interface between intact and failed rock is modelled. Jointing and lamination can be taken into account. An example of its use to determine displacements and stresses around a tunnel is presented. 885253 Axisymmetric fundamental solutions for a completely saturated porous elastic solid Puswewala, U G A; Rajapakse, R K N D Int J Engng Sci V26, N5, 1988, P419-436 Elastic deformations of saturated rocks or soils are of engineering importance. Fundamental solutions are derived in order to apply the boundary integral equation to poroelastic infinite and semi-infinite materials. Solutions considered are Laplace or time domain solutions for computational efficiency. Numerical results for vertical displacements and pore fluid pressure are presented for uniform and non-uniform buried patch loads acting in a vertical direction. 885254 Influence of out-of-plane stress on a plane strain problem in rock mechanics Reed, M B lnt J Num Anal Meth Geomech VI2, N2, March-April 1988, P173-181 Axisymmetric cavity expansion of a brittle Mohr-Coulomb rock in a hydrostatic stress field is examined. Previous plane strain displacement solutions have assumed out-of-plane stress remains the intermediate principal stress at all points. A displacement solution using a variable dilation plastic flow rule is given for the case when this assumption breaks down. Results are compared with previous solutions for specific problems. A significant difference is only found for problems with a large strength drop on yield. 885255 Unconditionally stable staggered solution procedures for soilpore fluid interaction problems Zienkiewicz, O C; Paul, D K; Chan, A H C lnt J Num Meth Engng V26, N5, May 1988, P1039-1055 A simple modified unconditionally stable implicit-implicit staggered approach is presented to describe soil-pore fluid interaction. It is simpler than the alternative proposed by Park. Soil-pore fluid interaction during earthquake and consolidation loading is examined, and numerical examples of 1 and 2-dimensional saturated poroelastic media are illustrated. 885256 Endochronic modeling of coupled volumetric-deviatoric behaviour of porous and granular materials Wu, H C; Aboutorabi, M R lnt J Plasticity V4, N2, 1988, P163-181 Constitutive behaviour of materials such as soils, rocks, concrete, or powders has been analysed using endochronic plasticity theory. Coupled volumetric-deviatoric behaviour, including volumetric deformation enhanced by shear loading
© 1988 Pergamon Press pie. Reproduction not permitted
234A and the enhancement of deviatoric deformation due to hydrostatic loads, is examined. The theory is applied to available results from concrete, and this application demonstrates a reasonably wide range of applicability of the model. 885257 Microcrack model of dilatancy in brittle materials Nemat-Nasser, S; Obata, M J Appl Mech (Trans ASME Set E) V5, N1, March 1988, P24-35 Nonlinear constitutive relations are developed for a model incorporating preexisting flaws with frictional and cohesive resistance, and which includes nucleation and growth of tension cracks at these flaws during deformation. A dilute distribution of preexisting flaws is assumed, and equations developed for loading and unloading, which include hysteresis, dilatancy and other characteristics observed in rocks and brittle materials. Illustrated examples are compared to experimental observations. 885258 Constitutive model for sands and clays evaluating principal stress rotation Matsuoka, H; Sakakibara, K Soils Found V27, N4, Dec 1987, P73-88 A constitutive equation is developed by which general strain increments are directly related to general stress increments. To evaluate the effects of principal stress rotation, experiments were carried out in a two dimensional general stress apparatus using a stack of aluminium rods to simulate soil particles. Test results agree well with predictions based on the model. Simple shear and liquefaction with principal stress rotation are analysed with the model. The model is extended to three dimensions using the superposition of the two dimensional principal strain increments. 885259 Modelling of non-linear behaviour of fractured seams in deep gold mines Brummer, R K Proc APCOM 87, Johannesburg, 19-23 October 1987 VI, P21-32. Publ Johannesburg: SAIMM, 1987 A simplified two dimensional plane strain model of tabular excavation in a brittle rock mass under high stress is presented. Relatively straightforward assumptions based on underground observations of fracturing and deformation at the stope base plus laboratory testing are made. The elastic rockmass remote from the reef is modelled using boundary elements, the reef rockmass using a linear string of yielding elements. Predicted and observed convergence and stresses during extraction of a remnant pillar are in good agreement. 88526O Three dimensional stress analysis: a practical planning tool for mining problems Diering, J A C; Stacey, T g Proc APCOM 87, Johannesburg, 19-23 October 1987 VI, P33-42. Publ Johannesburg: SAIMM, 1987 Mining involves excavations of finite size in infinite or semiinfinite rock masses. Three dimensional stress analysis using the boundary element method is discussed, the various types of boundary element considered, and the non conforming quadrilateral element, developed specifically for mining problems, introduced. Illustrated examples examine the interaction of excavations at great depth, open stope mining layout, and design of a drawpoint system for block caving.
885261 Three dimensional stress analysis of block caving mining layouts Esterhuizen, G S Proc APCOM 87, Johannesburg, 19-23 October 1987 VI. P43-48. Publ Johannesburg: SAIMM, 1987 Block caving is used to mine large orebodies in weak rock types. Development of extraction drives and drawpoints beneath the caving block further weakens the rock mass. Three dimensional boundary element analysis is used to examine the effect of alternative extraction level layouts on stress fields. Results indicate that the use of lateral pillars between drawpoints improves stability of extraction pillars and extraction drives. Further minor improvements are made by offsetting the lateral pillars.
Design methods 885262 Analysis of deep-level mine design problems using the MINSIM-D boundary element program Napier, J A L; Stephansen, S J Proe APCOM 87, Johannesburg, 19-23 October 1987 VI, P319. Publ Johannesburg: SAIMM, 1987 The theoretical background and novel solution procedures used in MINSIM-D are described. It can handle interaction from mining on multiple reefs, slip on weak fault planes, effect of backfill placement, and incremental mining sequences. -DIGITIZER and FRONT-END routines have been written to assist capture of mining outlines and general problem specifications. Suitable applications and further extensions of MINSIM-D are illustrated, and an example of its use presented. 885263 Identification of geometric characteristics of inhomogeneous rock masses by AIC method Ohnishi, Y; Higashide, A Proc International Symposium on Engineering in Complex Rock Formations, Beijing, 3-7 November 1986 1'945-950. Publ Beijing: Science Press, 1986 The basic concepts for estimating the geometric characteristics and material properties of a zoned rock mass from a limited number of field measurements are described. Elastic parameters are calculated using an optimisation procedure. The concepts of AIC (Akaike's Information Criterion) and MAICE (Minimum theoretical AIC Estimate) are introduced for optimum estimation of the boundaries of zones in inhomogeneous structures for constructing a geometrically suitable model.
Rock Breakage and Excavation Drilling 885264 Horizontal directional drilling Szczupak, J R Geodriiling N48, Feb 1988. PI 1-14 Horizontal directional drilling techniques are widely used to underpass obstacles when laying pipes or cables, on cost, environmental and protection grounds. The drilling procedure from initial set up, through pilot hole drilling and reaming, to
© 1988 Pergamon Press plc. Reproduction not permitted