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In-situ block size assessment from discontinuity spacing data
106A tunnels of the Abu-Tartour project in Egypt is described. Once blocks have been delineated, the optimum orientation for the tunnels can be computed.
932268 Three dimensional simulation of block size distribution of rock masses (In French) Xu, J; Cojean, R; Arnould, M Rev Fr Geotech N58, 1992, P31-40 A general method for simulation of three dimensional jointed rock masses is presented. The first stage is statistical generation of sets of disk-shaped fractures. This is followed by study of joint connectivity and identification of the distinct blocks delineated by these fractures. Characterization of the blocky rock mass is the final stage. Three possible methods for this are described: by size distribution; weighted size distribution; or orientation distribution. Field data are used to illustrate the procedures.
932269 Block modelling of jointed cliffs (In French) Homand-Etienne, F; Rode, N; Schwartzmann, R Rev Fr Geotech N58, 1992, P41-49 Field observations and modelling data relating to mining in limestone cliffs in the Loire valley are presented. The site geology and rock and joint properties are described. The distinct element code UDEC is used to simulate the excavation of a rectangular gallery in the cliff. Stresses and displacements around the underground opening are evaluated. Observed instabilities and stress levels measured using fiat jacks are compared to modelled data.
932270 3-D small displacement block model Gilbert, C M; Dowding, C H Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V1, P729-732. Publ Rotterdam: A A Balkema, 1991 A block formulation is presented for static and dynamic analysis of rock masses. The blocks are formed by intersection of multiple sets of joint planes defined by their strike, dip, and spacing. Block interactions occur along their common contact planes and are limited to small relative displacements. Both implicit and explicit formulations are developed for the static case and an explicit formulation for the dynamic analysis. Elastoplastic behaviour is assumed in shear along the joints and plastic sliding with dilation. Excavation and rock bolts can be simulated in the analysis. The model has been tested in a number of problems with 2-1200 blocks.
932271 Distinct element modelling of sublevel stoping Jing, L; Stephansson, O Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V1, P741-746. Publ Rotterdam: A A Balkema, 1991 As part of a program to improve productivity at the Kiruna mine, Sweden, a large scale sublevel stoping experiment was carried out. Rock mass behaviour during mining was simulated using the three dimensional distinct element method (3DEC), with a model containing 256 blocks and 9 major faults. Complicated block movement patterns were indicated, with displacements up to about 100mm. Calculated and measured stresses and displacements were in good agreement. Layout and mining sequence were modified, on the basis of modelling results, to avoid large ore losses and major failure.
932272 ln-situ block size assessment from discontinuity spacing data Wang, H; Latham, J P; Poole, A B Proc 6th International Congress International Association of Engineering Geology, Amsterdam, 6-10 August 1990, Symposia Pl17-127. Publ Rotterdam: A A Balkema, 1990 A relatively simple set of equations has been developed for predicting in situ block size distribution for a rock mass cut by three joint sets on the basis of mean spacings and mean orientations of the sets. Creation of the discontinuity data and determination of block size and shape parameters are described. Influences of joint persistence, sample size, the orthogonal assumption, dispersion, and the existence of more than three joint sets are discussed. Some applications are suggested.
Stress analysis See also: 932113, 932172, 932201, 932453
932273 Unified elasto-viscoplasticity model for clays, part h theory Liang, R Y; Ma, F Comput Geotecb II13, N2, 1992, P71-87 Phenomenological (macroscopic) behaviour of clays and existing elasto-viscoplasticity models are reviewed. A new constitutive model is formulated for the behaviour of saturated cohesive soils under general three dimensional stress conditions. The limit surface and the conjugated static yield surface form the basis from which time- and rate-effects can be accounted for by using a single state variable, the preconsolidation pressure.
932274 Unified elasto-viscoplasticity model for clays, part Ih verification Liang, R Y; Ma, F Comput Geotech F13, N2, 1992, P89-102 The elasto-viscoplastic model presented in part I (ibid, VI3, 1992, P71-78) is examined in detail. The physical meaning of the model parameters and techniques for their measurement are investigated. Model constants have been determined for two San Francisco Bay muds and a Saint-Aiban clay. The ability of the model to simulate the behaviour of these soils in drained and undrained creep tests, undrained stress relaxation tests, and drained triaxial tests with various stress paths is demonstrated.
932275 Discrete mechanical approach to granular materials Satake, M Int J Engng Sci V30, NIO, Oct 1992, P1525-1533 Earlier work which proposed a graph-theoretical approach in the mechanics of granular materials is extended from the case of circular particles to particles of arbitrary shape. The concept of dual particle is introduced and the role of voids emphasised. Quantities of force and displacement for particles, contact points, and voids are defined and their relations explained. Void force and displacement correspond to stress function and incompatibility in continuum mechanics. Some dualities existing in graphs of granular materials are discussed.
© 1993 Pergamon Press Ltd. Reproduction not permitted
932268 Three dimensional simulation of block size distribution of rock masses (In French) Xu, J; Cojean, R; Arnould, M Rev Fr Geotech N58, 1992, P31-40 A general method for simulation of three dimensional jointed rock masses is presented. The first stage is statistical generation of sets of disk-shaped fractures. This is followed by study of joint connectivity and identification of the distinct blocks delineated by these fractures. Characterization of the blocky rock mass is the final stage. Three possible methods for this are described: by size distribution; weighted size distribution; or orientation distribution. Field data are used to illustrate the procedures.
932269 Block modelling of jointed cliffs (In French) Homand-Etienne, F; Rode, N; Schwartzmann, R Rev Fr Geotech N58, 1992, P41-49 Field observations and modelling data relating to mining in limestone cliffs in the Loire valley are presented. The site geology and rock and joint properties are described. The distinct element code UDEC is used to simulate the excavation of a rectangular gallery in the cliff. Stresses and displacements around the underground opening are evaluated. Observed instabilities and stress levels measured using fiat jacks are compared to modelled data.
932270 3-D small displacement block model Gilbert, C M; Dowding, C H Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V1, P729-732. Publ Rotterdam: A A Balkema, 1991 A block formulation is presented for static and dynamic analysis of rock masses. The blocks are formed by intersection of multiple sets of joint planes defined by their strike, dip, and spacing. Block interactions occur along their common contact planes and are limited to small relative displacements. Both implicit and explicit formulations are developed for the static case and an explicit formulation for the dynamic analysis. Elastoplastic behaviour is assumed in shear along the joints and plastic sliding with dilation. Excavation and rock bolts can be simulated in the analysis. The model has been tested in a number of problems with 2-1200 blocks.
932271 Distinct element modelling of sublevel stoping Jing, L; Stephansson, O Proc 7th I S R M International Congress on Rock Mechanics, Aachen, 16-20 September 1991 V1, P741-746. Publ Rotterdam: A A Balkema, 1991 As part of a program to improve productivity at the Kiruna mine, Sweden, a large scale sublevel stoping experiment was carried out. Rock mass behaviour during mining was simulated using the three dimensional distinct element method (3DEC), with a model containing 256 blocks and 9 major faults. Complicated block movement patterns were indicated, with displacements up to about 100mm. Calculated and measured stresses and displacements were in good agreement. Layout and mining sequence were modified, on the basis of modelling results, to avoid large ore losses and major failure.
932272 ln-situ block size assessment from discontinuity spacing data Wang, H; Latham, J P; Poole, A B Proc 6th International Congress International Association of Engineering Geology, Amsterdam, 6-10 August 1990, Symposia Pl17-127. Publ Rotterdam: A A Balkema, 1990 A relatively simple set of equations has been developed for predicting in situ block size distribution for a rock mass cut by three joint sets on the basis of mean spacings and mean orientations of the sets. Creation of the discontinuity data and determination of block size and shape parameters are described. Influences of joint persistence, sample size, the orthogonal assumption, dispersion, and the existence of more than three joint sets are discussed. Some applications are suggested.
Stress analysis See also: 932113, 932172, 932201, 932453
932273 Unified elasto-viscoplasticity model for clays, part h theory Liang, R Y; Ma, F Comput Geotecb II13, N2, 1992, P71-87 Phenomenological (macroscopic) behaviour of clays and existing elasto-viscoplasticity models are reviewed. A new constitutive model is formulated for the behaviour of saturated cohesive soils under general three dimensional stress conditions. The limit surface and the conjugated static yield surface form the basis from which time- and rate-effects can be accounted for by using a single state variable, the preconsolidation pressure.
932274 Unified elasto-viscoplasticity model for clays, part Ih verification Liang, R Y; Ma, F Comput Geotech F13, N2, 1992, P89-102 The elasto-viscoplastic model presented in part I (ibid, VI3, 1992, P71-78) is examined in detail. The physical meaning of the model parameters and techniques for their measurement are investigated. Model constants have been determined for two San Francisco Bay muds and a Saint-Aiban clay. The ability of the model to simulate the behaviour of these soils in drained and undrained creep tests, undrained stress relaxation tests, and drained triaxial tests with various stress paths is demonstrated.
932275 Discrete mechanical approach to granular materials Satake, M Int J Engng Sci V30, NIO, Oct 1992, P1525-1533 Earlier work which proposed a graph-theoretical approach in the mechanics of granular materials is extended from the case of circular particles to particles of arbitrary shape. The concept of dual particle is introduced and the role of voids emphasised. Quantities of force and displacement for particles, contact points, and voids are defined and their relations explained. Void force and displacement correspond to stress function and incompatibility in continuum mechanics. Some dualities existing in graphs of granular materials are discussed.
© 1993 Pergamon Press Ltd. Reproduction not permitted