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Review of a thermodynamic theory for granular materials
107A 922270 High frequency acoustic emissionlmicroseismic studies associated with structural instabilities in underground mines Hardy, H R; Ersavci, M N Proc 2nd International Symposium on Rockbursts and Seismicity in Mines, Minneapolis, 8-10 June 1988 P199-204. Publ Rotterdam: A A Baikema, 1990 The application of high frequency AE/MS monitoring in underground mines is discussed. Localised monitoring of primary events associated with small local mechanical instabilities, and secondary monitoring of signals resulting in low level changes in local stress/strain conditions are considered. Local conditions are assumed to result from larger, more distant instabilities, such as those associated with rockburst or variation in overall abutment load distribution. Techniques and instrumentation are described.
922273 Key block analysis with statistical characterization of joints in tunnelling - a case stud.~ Cravero, M; Mahtab. -X: Grasso. P Pro(: Tunnelling '91, London, 14-18 April 1991 P93-100. Publ London: Elsevier, 199 / More realistic results are available from key block theory if variations in the block-forming joints are introduced than if a determimistic approach is taken. The effect of coupled influences of variations in joint orientation and joint friction is examined using field data from gneiss and schist rocks. Joint orientation is selected using the Monte Carlo technique. The angle of friction is selected at a probability level of 0.95 from extremal distribution of tilt friction data, and, for comparison, a mean value of an assumed normal distribution is assumed. Key block restraining forces are markedly different for the two values of friction angle.
Stress analysis
Analysis Techniques and Design Methods See: 922080, 922413
Rock block analysis 922271 Statistical analysis of jointed rock data Shapiro, A; Delport, J L lnt J Rock Mevh Min Sci V28, N5, Sept 1991, P375-382 The case of tunnelling into a rock mass composed of distinct blocks bounded by families of roughly parallel joints is examined. Some of the blocks will come into contact with the excavation face and may form keybiocks. Three problems are considered: estimation of the number of keyblocks per square metre of tunnel wall; evaluation of the probability distribution of keyblock volume; and estimation of the probability that a suspected keyblock, revealed as a closed polygon on the tunnel face, may form a keyblock. The analysis uses Monte Carlo methods and simulations.
922272 Probabilistic method for predicting key blocks Tyler, D B; Trueman, R; Pine, R J Min Sci Technol I,'13, N2, Sept 1991, P145-156 Probabilistic distributions fitted to joint mapping data from South Crofty mine were used in a simple deterministic model of rock jointing. This was used in key block analysis. The inherent limitations of this approach indicate the desirability of probabilistic analysis. The limitations of existing analyses of this type are examined. An improved analysis is developed which uses discrete samples from continuous input, which is randomly selected without repetition using latin hypercube sampling. The code developed, B3LHS, is seen to delineate more key blocks than the deterministic model, and the probability of formation of key blocks can now be calculated.
922274 Numerical modelling as a tool in stope design Packalnis, R; Tenney, D; Lang, B CIM Bull 1/84, N951, July 1991, P64-72 Three case histories are described where numerical methods were used to identify areas of potential instability in underground mines. Two dimensional (PCBEM) and pseudo three dimensional (BESOL, MINTAB) codes were used. Sill pillar stability at MacLellan Mine, hanging wall stability at Ruttan Mine, and narrow vein open stoping at Detour Lake Mine were modelled. Predictions from numerical models were compared to stress meter, extensometer, and observational data, as the stopes were excavated.
922275 Review of a thermodynamic theory for granular materials Sengupta, A; Saxena, S Comput Geotech VII, NI, 1991, P1-36 The thermodynamic model of frictional materials of Valanis and Peters (1988) is reviewed. The model, which does not require any a priori yield criteria, degenerates to different elastic plastic theories as special cases. It takes into account initial and stress-induced anisotropy, compressibility, and stress path dependency. A complete derivation from the first principles of thermodynamics is presented. Material parameter determination is demonstrated for ordinary and cemented sands, to illustrate the different features of the model and its ability to describe a range of material behaviours.
922276 Double hardening elastoplastic model for the behaviour of bulk solids at low stresses. Technical note Lancelot, L; Shahrour, I Comput Geateck VII, N2, 1991, P147-158 Development and validation of a constitutive model for granular materials under low stress conditions was undertaken for application to storage and handling problems. Data from oedometric, triaxial compression, and triaxial extension tests were used in the work. A parametric analysis was used to determine which parameters have major influence on response of the model under triaxial compression and oedometric stress paths. Uses and limitations are discussed.
© 1992 Pergamon Press Ltd. Reproduction not permitted
922273 Key block analysis with statistical characterization of joints in tunnelling - a case stud.~ Cravero, M; Mahtab. -X: Grasso. P Pro(: Tunnelling '91, London, 14-18 April 1991 P93-100. Publ London: Elsevier, 199 / More realistic results are available from key block theory if variations in the block-forming joints are introduced than if a determimistic approach is taken. The effect of coupled influences of variations in joint orientation and joint friction is examined using field data from gneiss and schist rocks. Joint orientation is selected using the Monte Carlo technique. The angle of friction is selected at a probability level of 0.95 from extremal distribution of tilt friction data, and, for comparison, a mean value of an assumed normal distribution is assumed. Key block restraining forces are markedly different for the two values of friction angle.
Stress analysis
Analysis Techniques and Design Methods See: 922080, 922413
Rock block analysis 922271 Statistical analysis of jointed rock data Shapiro, A; Delport, J L lnt J Rock Mevh Min Sci V28, N5, Sept 1991, P375-382 The case of tunnelling into a rock mass composed of distinct blocks bounded by families of roughly parallel joints is examined. Some of the blocks will come into contact with the excavation face and may form keybiocks. Three problems are considered: estimation of the number of keyblocks per square metre of tunnel wall; evaluation of the probability distribution of keyblock volume; and estimation of the probability that a suspected keyblock, revealed as a closed polygon on the tunnel face, may form a keyblock. The analysis uses Monte Carlo methods and simulations.
922272 Probabilistic method for predicting key blocks Tyler, D B; Trueman, R; Pine, R J Min Sci Technol I,'13, N2, Sept 1991, P145-156 Probabilistic distributions fitted to joint mapping data from South Crofty mine were used in a simple deterministic model of rock jointing. This was used in key block analysis. The inherent limitations of this approach indicate the desirability of probabilistic analysis. The limitations of existing analyses of this type are examined. An improved analysis is developed which uses discrete samples from continuous input, which is randomly selected without repetition using latin hypercube sampling. The code developed, B3LHS, is seen to delineate more key blocks than the deterministic model, and the probability of formation of key blocks can now be calculated.
922274 Numerical modelling as a tool in stope design Packalnis, R; Tenney, D; Lang, B CIM Bull 1/84, N951, July 1991, P64-72 Three case histories are described where numerical methods were used to identify areas of potential instability in underground mines. Two dimensional (PCBEM) and pseudo three dimensional (BESOL, MINTAB) codes were used. Sill pillar stability at MacLellan Mine, hanging wall stability at Ruttan Mine, and narrow vein open stoping at Detour Lake Mine were modelled. Predictions from numerical models were compared to stress meter, extensometer, and observational data, as the stopes were excavated.
922275 Review of a thermodynamic theory for granular materials Sengupta, A; Saxena, S Comput Geotech VII, NI, 1991, P1-36 The thermodynamic model of frictional materials of Valanis and Peters (1988) is reviewed. The model, which does not require any a priori yield criteria, degenerates to different elastic plastic theories as special cases. It takes into account initial and stress-induced anisotropy, compressibility, and stress path dependency. A complete derivation from the first principles of thermodynamics is presented. Material parameter determination is demonstrated for ordinary and cemented sands, to illustrate the different features of the model and its ability to describe a range of material behaviours.
922276 Double hardening elastoplastic model for the behaviour of bulk solids at low stresses. Technical note Lancelot, L; Shahrour, I Comput Geateck VII, N2, 1991, P147-158 Development and validation of a constitutive model for granular materials under low stress conditions was undertaken for application to storage and handling problems. Data from oedometric, triaxial compression, and triaxial extension tests were used in the work. A parametric analysis was used to determine which parameters have major influence on response of the model under triaxial compression and oedometric stress paths. Uses and limitations are discussed.
© 1992 Pergamon Press Ltd. Reproduction not permitted