- Email: [email protected]
Consistent lumped-parameter models for unbounded soil: physical representation
236A time domain, whereby the structure can be nonlinear. High accuracy of results can be achieved, even for dynamic systems with a cutoff frequency.
914294 Generalized nonassociative multisurface approach for granular materials Pan, Y W
914290 Consistent lumped-parameter models for unbounded soil: frequency-independent stiffness, damping and mass matrices Wolf, J P Earthq Engng Struct Dynam ~ 0 . NI, Jan 1991. P33-41
J Geotech Engng Div ASCE VIIT. NI. Jan 1991. P51-66
A systematic procedure to develop symmetric stiffness, damping, and mass matrices with real coefficients to represent an unbounded soil is described. These property matrices are based on lumped parameter models from previously published work (ibid, V20, NI, P11-32). The matrices can be easily incorporated into general purpose structural dynamics programs within the time domain.
914291 Continuous and discontinuous contact problems for strips on an elastic semi-infinite plane Cakiroglu, A O; Cakiroglu, F L lnt J Engng Sci V29. NI. 1991. P99-111
In the problem of beams or plates resting on an elastic half space, intensity of the applied force, height and length of the plate or beam, and material properties have important effects on the formation of the initial separation point and stress distribution at the contact surface. A general solution is here obtained from general loading conditions, in which special loading conditions are considered. Loading is continued until the point of initial separation. The singular integral equation obtained from the discontinuous contact problem is solved numerically by the Gauss-Chebyshev integration method.
914292 Linearized integration technique for incremental constitutive equations Bardct, J P; Choucair, W Int J Num Anal Meth Geomech l"15, NI. Jan 1991, PI-19
A numerical technique is proposed for obtaining stress strain response curves from rate type and incremental constitutive equations during generalized loading. Loading constraints of laboratory tests are linearized and linked to the constitutive equations to form a linear system of ordinary differential equations, thus avoiding difficulties due to non-uniqueness or bifurcation of boundary value problems. The method is illustrated for elastoplastic von Mises and Roscoe and Burland models in torsion, circular stress path, and undrained triaxial tests.
914293 User-friendly interface for computer aided analysis and design in mining. Technical note Beer, G; Mertz, W lnt J Rock Much Min Sci V27. :V6, Dec 1990, P541-552
Three dimensional analysis of stresses around underground structures requires large quantities of input data, and operation by engineers without experience of computer modelling can be difficult. To remedy this,an AMIRA project was set up to develop a hardware and program independent graphical pre-processor. It consists of three independent programs: F E M D I G for digitising cross sections; FEMCAD for generating finite or boundary element meshes; and F E M N U M for extracting element, surface, and node numbers for specifying material properties or load data. The user interface, geometry definition, mesh generation, and examples are illustrated.
A generalised transitional yielding approach with any number of limit surfaces, which represent the various degrees of the hierarchical material memory due to stress history, is proposed. A new approach is formulated for describing the nonassociative behaviour of granular materials which does not require different functions for the yield and plastic potential surfaces. A unique and smooth definition of loading, unloading, and reloading, without the need for a fixed conjugate point, is developed. The two surface and infinite yield surface models can be considered as special cases of the proposed model.
914295 Automated slope stability analysis using mathematical programming technique Basudhar, P K; Yudhbir Proc International Symposium on Computer and Physical Modelling in Geoteclmical Engineering, Bangkok, 3-6 December 1986 [81-88. Publ Rotterdam: A A Balkema, 1989 Slope stability analysis is essentially a problem of optimisation, identification of the slip surface with the minimum factor of safety. An analysis using the Sequential Unconstrained Optimisation Technique has been formulated to allow autosearch for the critical slip surface using Janbu's GPS method, with no prior assumptions on the shape of the failure surface. It can be used for homogeneous and heterogeneous embankment sections and has been expanded to the case of a foundation containing a thin shear zone.
914296 Constitutive models of rock joints Amadei, B; Saeb, S Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P581-594. Publ Rotterdam." A A Balkema. 1990
A method is presented to determine the effects of boundary conditions on shear behaviour of a dilatant rock joint. It can be calibrated from the normal stress-displacement response curves and shear stress-displacement and dilatancy response under constant normal stress. It is presented in both graphical and mathematical forms. The latter predicts increase in normal deformability as an initially mated joint traverses unmated conditions. A nonlinear incremental formulation of rock joint deformability is presented which fully accounts for the coupling between joint normal and shear response due to dilatancy. 914297 Two dimensional constitutive model of rock joints with pre-and post-peak behaviour Lanru Jing Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P633-638. Publ Rotterdam. A A Balkema. 1990
An explicit incremental constitutive model for" rock joints is formulated using classical plasticity theory. Pre- and post-peak failure are modelled using hardening and softening laws. Nonlinear and finite shear dilation is simulated by a nonassociated flow rule. Joint stiffness can depend on normal stress. Plesha's exponential decay function of asperity angle is used to model joint surface degradation. The predictions of the model are in good agreement with some published experimental data.
C' 1991 Pergamon Press plc. Reproduction not permitted
914294 Generalized nonassociative multisurface approach for granular materials Pan, Y W
914290 Consistent lumped-parameter models for unbounded soil: frequency-independent stiffness, damping and mass matrices Wolf, J P Earthq Engng Struct Dynam ~ 0 . NI, Jan 1991. P33-41
J Geotech Engng Div ASCE VIIT. NI. Jan 1991. P51-66
A systematic procedure to develop symmetric stiffness, damping, and mass matrices with real coefficients to represent an unbounded soil is described. These property matrices are based on lumped parameter models from previously published work (ibid, V20, NI, P11-32). The matrices can be easily incorporated into general purpose structural dynamics programs within the time domain.
914291 Continuous and discontinuous contact problems for strips on an elastic semi-infinite plane Cakiroglu, A O; Cakiroglu, F L lnt J Engng Sci V29. NI. 1991. P99-111
In the problem of beams or plates resting on an elastic half space, intensity of the applied force, height and length of the plate or beam, and material properties have important effects on the formation of the initial separation point and stress distribution at the contact surface. A general solution is here obtained from general loading conditions, in which special loading conditions are considered. Loading is continued until the point of initial separation. The singular integral equation obtained from the discontinuous contact problem is solved numerically by the Gauss-Chebyshev integration method.
914292 Linearized integration technique for incremental constitutive equations Bardct, J P; Choucair, W Int J Num Anal Meth Geomech l"15, NI. Jan 1991, PI-19
A numerical technique is proposed for obtaining stress strain response curves from rate type and incremental constitutive equations during generalized loading. Loading constraints of laboratory tests are linearized and linked to the constitutive equations to form a linear system of ordinary differential equations, thus avoiding difficulties due to non-uniqueness or bifurcation of boundary value problems. The method is illustrated for elastoplastic von Mises and Roscoe and Burland models in torsion, circular stress path, and undrained triaxial tests.
914293 User-friendly interface for computer aided analysis and design in mining. Technical note Beer, G; Mertz, W lnt J Rock Much Min Sci V27. :V6, Dec 1990, P541-552
Three dimensional analysis of stresses around underground structures requires large quantities of input data, and operation by engineers without experience of computer modelling can be difficult. To remedy this,an AMIRA project was set up to develop a hardware and program independent graphical pre-processor. It consists of three independent programs: F E M D I G for digitising cross sections; FEMCAD for generating finite or boundary element meshes; and F E M N U M for extracting element, surface, and node numbers for specifying material properties or load data. The user interface, geometry definition, mesh generation, and examples are illustrated.
A generalised transitional yielding approach with any number of limit surfaces, which represent the various degrees of the hierarchical material memory due to stress history, is proposed. A new approach is formulated for describing the nonassociative behaviour of granular materials which does not require different functions for the yield and plastic potential surfaces. A unique and smooth definition of loading, unloading, and reloading, without the need for a fixed conjugate point, is developed. The two surface and infinite yield surface models can be considered as special cases of the proposed model.
914295 Automated slope stability analysis using mathematical programming technique Basudhar, P K; Yudhbir Proc International Symposium on Computer and Physical Modelling in Geoteclmical Engineering, Bangkok, 3-6 December 1986 [81-88. Publ Rotterdam: A A Balkema, 1989 Slope stability analysis is essentially a problem of optimisation, identification of the slip surface with the minimum factor of safety. An analysis using the Sequential Unconstrained Optimisation Technique has been formulated to allow autosearch for the critical slip surface using Janbu's GPS method, with no prior assumptions on the shape of the failure surface. It can be used for homogeneous and heterogeneous embankment sections and has been expanded to the case of a foundation containing a thin shear zone.
914296 Constitutive models of rock joints Amadei, B; Saeb, S Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P581-594. Publ Rotterdam." A A Balkema. 1990
A method is presented to determine the effects of boundary conditions on shear behaviour of a dilatant rock joint. It can be calibrated from the normal stress-displacement response curves and shear stress-displacement and dilatancy response under constant normal stress. It is presented in both graphical and mathematical forms. The latter predicts increase in normal deformability as an initially mated joint traverses unmated conditions. A nonlinear incremental formulation of rock joint deformability is presented which fully accounts for the coupling between joint normal and shear response due to dilatancy. 914297 Two dimensional constitutive model of rock joints with pre-and post-peak behaviour Lanru Jing Proc International Symposium on Rock Joints, Loen, 4-6 June 1990 P633-638. Publ Rotterdam. A A Balkema. 1990
An explicit incremental constitutive model for" rock joints is formulated using classical plasticity theory. Pre- and post-peak failure are modelled using hardening and softening laws. Nonlinear and finite shear dilation is simulated by a nonassociated flow rule. Joint stiffness can depend on normal stress. Plesha's exponential decay function of asperity angle is used to model joint surface degradation. The predictions of the model are in good agreement with some published experimental data.
C' 1991 Pergamon Press plc. Reproduction not permitted