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The use of infinite element
ROCK BREAKAGE:GENERAL mentally in 62 production blasts to confirm the validity of the work. (Authors)
966226 Empirical design in geotechnics using neural networks A. T. C. Gob, Geotechnique, 45(4), 1995, pp 709-714. This technical note uses a practical example to show the potential of neural networks to improve the synthesizing of the information for the development of empirical design aids. Problem domains in which the behaviour of the system is governed by non-linear multivariate relationships, and where reliable case records are available, offer the greatest promise. (from Author)
269A
966231 Estimation of parameters in geotechnical backanalysis - II. Application to a tunnel excavation problem A. Gens, A. Ledesma & E. E. Alonso, Computers & Geotechnics, 18(1), 1996, pp 29-46. Application to a real backanalysis case involving the excavation of a tunnel in stiff overconsolidated clay is described. both, extensometer and inclinometer measurements are used as input data and elastic moduli of the ground and the value of the Ko coefficient are estimated. The finite element method is used as the computational procedure to solve the direct problem, and has been coupled to the identification algorithm. A discussion on the reliability of the parameters identified is presented. (from Authors)
966227 Modelling unknown structural systems through the use of neural networks A. G. Chassiakos & S. F. Masri, Earthquake Engineering & Structural Dynamics, 25(2), 1996, pp 117-128. This paper explores the potential of using neural networks to identify the internal forces of typical systems encountered in the field of earthquake engineering and structural dynamics. After formulating the identification task as a neural network learning procedure, the method is applied to a representative chain-like system under deterministic and stochastic excitations. (from Authors)
966232 Finite layer analysis of vertically loading piles and pile groups P. H. Southcott & J. C. Small, Computers & Geotechnics, 18(1), 1996, pp 47-63. The method uses a finite layer technique to idealize soil as finite layers of infinite horizontal extent. It is shown that the solutions obtained for a single pile and pile groups in uniform soils compares favourable with existing solutions. Significant differences were found when compared with approximate solutions for non-uniform soils. It is concluded that the finite layer technique provides a more accurate solution. Finally, a limited parametric study of the effects of a stiff stratum within a soft soil is presented. (from Authors)
966228 A fuzzy neural network approach to evaluation of slope failure potential S. H. Ni, P. C. Lu & C. H. Juang, Microcomputers in Civil Engineering, 11(!), 1996, pp 59-66. In this approach, fuzzy sets are used to represent the parameters of the neural network. A total of 13 factors that are believed to be important to the stability of natural slopes are used as input parameters. A two-stage training method is used for establishing fuzzy parameters. A fuzzy artificial neural network is developed and tested. A number of hypothetical natural slopes are evaluated, and the results appear to be reasonable compared with those obtained by different approaches in a previous study. (from Authors)
966233 The use of infinite element Y. M. Cheng, Computers & Geotechnics, 18(1), 1996, pp 6570. In most practical geotechnical problems, the actual domain of soil and rock extends to infinity. For numerical analysis, a finite domain is however commonly used for preparation of finite element mesh which may, however, introduce end effects in computation. Problems involving infinite domain is best modelled with infinite element. The inclusion of body forces (gravity) in the gravity turn-on process with the use of infinite element, however, requires special care and this is considered in the present paper. (Author)
966229 Modelled on reality G. Shirley, Surveyor, 182(5369), 1995, pp 22-23. Developments in virtual reality (VR) technology are described. Although immersive VR is still in its infancy, desktop VR is being widely used for engineering and construction applications. Desktop VR images are in the form of a three-dimensional environment created on a threedimensional PC screen through which the user can navigate. Typical applications of desktop VR for tunnelling modelling and traffic modelling are discussed. (P.M.Taylor) 966230 Estimation of parameters in geotechnical back analysis - I. Maximum likelihood approach A. Ledesma, A. Gens & E. E. Alonso, Computers & Geotechnics, 18(l), 1996, pp 1-27. A probabilistic formulation for the backanalysis problem is presented. The procedure described involves the evaluation of the measurement covariance matrices, which arc derived for some geotechnical instruments used in field instrumentation. The algorithm used to solve the mathematical problem of optimization is also presented, as well as its coupling to a finite element code. A synthetic example, based on the excavation of a tunnel, is presented in which the elastic modulus E and the K0 parameter of the material are identified from measured displacements. The effect of the number of measurements and their error structure is also discussed. (from Authors)
966234 On the numerical modeling of convex particle assemblies with friction M. A. Tzaferopoulos, Computer Methods in Applied Mechanics & Engineering, 127(1-4), 1995, pp 371-386. A quasi-static model is proposed for the simulation of dense, randomly packed assemblies consisting of convex bodies and undergoing slow deformation. A second order approximation of the contact and sticking friction conditions is derived. The solution of the assembly equilibrium problem is approximated by a sequence of nonsmooth potential minimization problems. For the treatment of the nonlinearity a second order approximation is introduced. For the line search the nonlinear constraints are expressed with the aid of exact penalty functions. The addition of a second order correction step is critical for the algorithm. (from Author)
ROCK BREAKAGE AND EXCAVATION General 966235 Changing imperatives of architecture affecting dimension stone use in world commerce W. H. McDonald & D. D. Carr, Mining Engineering, 48(1), 1996, pp 49-52. The use of stone in building construction predates written history. From the time that stone was first used, builders have
966226 Empirical design in geotechnics using neural networks A. T. C. Gob, Geotechnique, 45(4), 1995, pp 709-714. This technical note uses a practical example to show the potential of neural networks to improve the synthesizing of the information for the development of empirical design aids. Problem domains in which the behaviour of the system is governed by non-linear multivariate relationships, and where reliable case records are available, offer the greatest promise. (from Author)
269A
966231 Estimation of parameters in geotechnical backanalysis - II. Application to a tunnel excavation problem A. Gens, A. Ledesma & E. E. Alonso, Computers & Geotechnics, 18(1), 1996, pp 29-46. Application to a real backanalysis case involving the excavation of a tunnel in stiff overconsolidated clay is described. both, extensometer and inclinometer measurements are used as input data and elastic moduli of the ground and the value of the Ko coefficient are estimated. The finite element method is used as the computational procedure to solve the direct problem, and has been coupled to the identification algorithm. A discussion on the reliability of the parameters identified is presented. (from Authors)
966227 Modelling unknown structural systems through the use of neural networks A. G. Chassiakos & S. F. Masri, Earthquake Engineering & Structural Dynamics, 25(2), 1996, pp 117-128. This paper explores the potential of using neural networks to identify the internal forces of typical systems encountered in the field of earthquake engineering and structural dynamics. After formulating the identification task as a neural network learning procedure, the method is applied to a representative chain-like system under deterministic and stochastic excitations. (from Authors)
966232 Finite layer analysis of vertically loading piles and pile groups P. H. Southcott & J. C. Small, Computers & Geotechnics, 18(1), 1996, pp 47-63. The method uses a finite layer technique to idealize soil as finite layers of infinite horizontal extent. It is shown that the solutions obtained for a single pile and pile groups in uniform soils compares favourable with existing solutions. Significant differences were found when compared with approximate solutions for non-uniform soils. It is concluded that the finite layer technique provides a more accurate solution. Finally, a limited parametric study of the effects of a stiff stratum within a soft soil is presented. (from Authors)
966228 A fuzzy neural network approach to evaluation of slope failure potential S. H. Ni, P. C. Lu & C. H. Juang, Microcomputers in Civil Engineering, 11(!), 1996, pp 59-66. In this approach, fuzzy sets are used to represent the parameters of the neural network. A total of 13 factors that are believed to be important to the stability of natural slopes are used as input parameters. A two-stage training method is used for establishing fuzzy parameters. A fuzzy artificial neural network is developed and tested. A number of hypothetical natural slopes are evaluated, and the results appear to be reasonable compared with those obtained by different approaches in a previous study. (from Authors)
966233 The use of infinite element Y. M. Cheng, Computers & Geotechnics, 18(1), 1996, pp 6570. In most practical geotechnical problems, the actual domain of soil and rock extends to infinity. For numerical analysis, a finite domain is however commonly used for preparation of finite element mesh which may, however, introduce end effects in computation. Problems involving infinite domain is best modelled with infinite element. The inclusion of body forces (gravity) in the gravity turn-on process with the use of infinite element, however, requires special care and this is considered in the present paper. (Author)
966229 Modelled on reality G. Shirley, Surveyor, 182(5369), 1995, pp 22-23. Developments in virtual reality (VR) technology are described. Although immersive VR is still in its infancy, desktop VR is being widely used for engineering and construction applications. Desktop VR images are in the form of a three-dimensional environment created on a threedimensional PC screen through which the user can navigate. Typical applications of desktop VR for tunnelling modelling and traffic modelling are discussed. (P.M.Taylor) 966230 Estimation of parameters in geotechnical back analysis - I. Maximum likelihood approach A. Ledesma, A. Gens & E. E. Alonso, Computers & Geotechnics, 18(l), 1996, pp 1-27. A probabilistic formulation for the backanalysis problem is presented. The procedure described involves the evaluation of the measurement covariance matrices, which arc derived for some geotechnical instruments used in field instrumentation. The algorithm used to solve the mathematical problem of optimization is also presented, as well as its coupling to a finite element code. A synthetic example, based on the excavation of a tunnel, is presented in which the elastic modulus E and the K0 parameter of the material are identified from measured displacements. The effect of the number of measurements and their error structure is also discussed. (from Authors)
966234 On the numerical modeling of convex particle assemblies with friction M. A. Tzaferopoulos, Computer Methods in Applied Mechanics & Engineering, 127(1-4), 1995, pp 371-386. A quasi-static model is proposed for the simulation of dense, randomly packed assemblies consisting of convex bodies and undergoing slow deformation. A second order approximation of the contact and sticking friction conditions is derived. The solution of the assembly equilibrium problem is approximated by a sequence of nonsmooth potential minimization problems. For the treatment of the nonlinearity a second order approximation is introduced. For the line search the nonlinear constraints are expressed with the aid of exact penalty functions. The addition of a second order correction step is critical for the algorithm. (from Author)
ROCK BREAKAGE AND EXCAVATION General 966235 Changing imperatives of architecture affecting dimension stone use in world commerce W. H. McDonald & D. D. Carr, Mining Engineering, 48(1), 1996, pp 49-52. The use of stone in building construction predates written history. From the time that stone was first used, builders have