bluuebunny/crossref_metadata_2025_split huggingface dataset:
Deformation behaviour of Talbingo Dam
Authors: Adikari G. S. N. , Parkin A. K. 
Published: August 2005

AbstractTalbingo Dam is a well instrumented, 162m high rockfill structure with an upstream sloping silty clay core, located in the southern New South Wales, Australia. A non‐linear finite element analysis of its behaviour was carried out under plane strain conditions, simulating its construction, reservoir filling and steady seepage loading stages. Material parameters are determined from triaxial tests on the rockfill, core, filter and transition materials, compacted to field dry density and moisture content. All materials show non‐linear stress–strain behaviour, with rockfill exhibiting work softening at large strain. Mohr envelopes for rockfill are slightly curved but linear approximations are acceptable. When compared with stresses and deformations at maximum cross section, the analytical results show good agreement in most areas. A non‐linear model for pore pressure response is used successfully to predict the high pore pressures in the lower region of the core. A stability analysis performed for the end of construction stage, based on finite element stresses, shows that the design safety factors are slightly conservative.
Finite‐element modelling of folding and faulting
Authors: Reddy J. N. , Stein R. J. , Wickham J. S. 
Published: August 2005

AbstractThe paper is concerned with the finite‐element modelling of geologic phenomena. More specifically, the paper presents numerical models of folding and sait doming. A (penalty‐) finite‐element model based on the equations governing a viscous incompressible fluid is used to simulate the folding is used to simulate the folding of a viscous layer in a less viscous matrix and the salt dome formation, and to predict the location of active faulting and deformation in prograding delta systems on continentalmargins. The initiation and development of drape folding and associated faulting are also modelled. The United States continental margin of the Gulf of Mexico is used as an example of prograding delta system. The finite‐element predictions seem to agreewith the published results.
Finite‐element modelling of fracture density in single layer folds
Authors: Wickham J. S. , Tapp G. S. , Reddy J. N. 
Published: August 2005

AbstractThe present study is a continuation of the numerical modelling of geologic structures by the authors (see J. N. Reddyet al., Finite‐element modelling of folding and faulting, this journal). The present paper is concerned with the computation of the stress and fracture density distributions in single layer folds by the finite‐element method. It was found that variations in fracture patterns are related to several variables: (i) the viscosity of the competent layer, (ii) the ratio of the viscosity of the competent layer to the viscosity of the matrix, (iii) the cohesive strength of the material, and (iv) the boundary velocities during deformation. The fracture prediction is based on the Mohr–Coulomb criterion, which is a function of the stresses only. Prediction of fracture density is based on a function of the strain energy. It is found that there is a good correlation between the computer predicted fractures and the fracture pattern produced by the expermental buckiing of rock‐beams. Itis, concluded that the viscosity ratio controls the location of fractures in single layer folds.
Propagation of shock waves at the surface of heterogeneous soil grounds
Authors: Holzlöhner U. , Auersch L. 
Published: August 2005

AbstractThe paper deals with the propagation of shock waves at the surface of soils. Heterogeneity and damping are introduced into analytical half‐space solutions. The suggested model explains two phenomena, often observed with shock propagation in actual soils, that differ from the behaviour of the homogeneous half‐space: the pronounced decay of the disturbances with distance and the elongation of the disturbance into a train of waves. The effects of heterogeneity and damping are discussed quantitatively.The response of footings on heterogeneous soils has been investigated by several authors. Awojobi4 considered the Gibson soil in which the shear modulus increases linearly with depth. Luco5 and Gazetas and Roesset6 investigated a multi‐layered soil, the shear modulus being constant within each layer. Gazetas7, using a technique suggested by Gupta8 extended this method to layers with linearly varying shear modulus. Little work is available on the propagation of waves in heterogeneous bodies. Some results concerning the modes and the mode shapes in heterogeneous soils were reported by Ewing, Jardetzky and Press9 and Bath.10 The modes have to be superposed in an appropriate way to obtain the displacement field at the surface. This has been approximately achieved by the finite element formulations of Lysmer, 11, Lysmer and Waas12 and Waas.13 Auersch14 applied this method to a homogeneous layer on a rigid base. He found some dispersion of the Rayleigh wave within a narrow frequency range. Finite elements combined with discrete Laplace transforms, however, consume much computer time. Rao and Goda15 and Rao16 calculated surface vibrations of a half‐space with exponentially varying shear modulus and density. Their method is similar to Lamb'S1 procedure for the homogeneous half‐space. Only one mode–the Rayleigh wave–occurs in their heterogeneous half‐space. The examples show the considerable effect of heterogeneity on wave propagation. In the present paper, more general variations of the shear modulus are considered.
An analytical solution for the transient response of saturated porous elastic solids
Authors: Simon B. R. , Zienkiewicz O. C. , Paul D. K. 
Published: August 2005

AbstractThe general forms for the field equations governing the transient response of poroelastic media given by Biot and by Zienkiewicz are compared and relations between the material constants are obtained. A one‐dimensional analytical solution is presented for the situation where the solid and fluid materials satisfy Biot'S dynamic compatibility relation. The transient response of porous media is illustrated for varying degrees of solid and fluid compressibility when subjected to step, cyclic and short duration spike surface tractions. The results obtained (for the special situation where the materials are dynamically compatible) exhibit the overall characteristics of wave propagation in porous media and will provide representative test problems which allow a quantitative evaluation of the accuracy of various numerical solution methods (e.g. finite element models).
Seepage analysis in a zoned anisotropic medium by the boundary element method
Authors: Chugh Ashok K. , Falvey Henry T. 
Published: August 2005

AbstractA simple and effective extension to the boundary element method for solving Laplace'S equation (∇2u = 0) for boundary value problems is presented to solve steady confined and (or) steady unconfined seepage problems in zoned anisotropic mediums. Sample problems indicating the accuracy of results are given.
A non‐linear rheological analysis of deeply located tunnels
Authors: Akagi Tomoyuki , Ichikawa Yasuaki , Kuroda Hidetaka , Kawamoto Toshikazu 
Published: August 2005

AbstractA rheological model which is able to explain the delayed failure phenomenon has been proposed and applied to the analysis of the time dependent behaviour of deep tunnels. The model is the three element Voigt type before yielding and becomes the five element Voigt type after yielding. This means that the stiffness of the model is decreased by yielding. It is assumed that the yielding takes place when the stored elastic energy density of distortion reaches a certain maximum value. Some experiments to determine material constants are proposed. The numerical results clearly exhibited a delayed failure state of the rock masses around the tunnel surface. It was found that the extension of the yielding zone due to tunnel excavation depends on the opening method.
Plate loading tests on sloping rock
Authors: Vreede F. A. 
Published: August 2005

AbstractThe plate loading test is performed in order to determine the deformation modulus of a rock mass in situ. In the standard execution of this test the loading is applied perpendicular to the rock surface. The displacements are measured on the axis of symmetry, since for an isotropic material with linear deformation characteristics exact formulae are known which are valid at this location. For horizontal strata this presents no problem as it is easy to provide loading in a vertical direction. When the rock strata are dipping it is imprectical to use nonvertical load and it is then necessary to calculate the modulus from the displacements in a non‐axisymmetrical arrangement. Using the well‐known method of the Taylor series approximate formulae are derved which are sufficiently accurate for all practical cases of sloping rock.
Implementation of a general constitutive model for geological materials
Authors: Faruque M. O. , Desai C. S. 
Published: August 2005

AbstractA generalized constitutive model is described with particular attention to determination of material constants, and its implementation. The model involves use of only a single function to characterize the complete range of plastic yielding, and employs a special function to describe plastic hardening. Laboratory behaviour of an artificial soil is used to iliustrate the determination of the constants and verification of the model.
A quasi‐explicit modification of the two time level family of schemes for non‐linear transient analysis
Authors: Kujawski J. , Desai C. S. 
Published: August 2005

AbstractA quasi‐explicit modification of well‐known two time level implicit schemes for first‐order, non‐linear initial value problems is presented. Stable and accurate quadratic families for the quasi‐explicit generalized trapezoidal method (GTM) and the generalized midpoint method (GMM) are derived. Accuracy, stability and oscillatory behaviour of the proposed algorithms are studied. Much higher stability and oscillatory levels are obtained for quasi‐explicit modification of the generalized trapezoidal method than those of the generalized midpoint method.
Simple model for transient soil loading in earthquake analysis. I. Basic model and its application
Authors: Zienkiewicz O. C. , Leung K. H. , Pastor M. 
Published: August 2005

AbstractSeveral models describing soil response under cyclic loading and the ‘liquefaction’ potential have been introduced in recent years with limited success. Most of these are over‐complex for realistic parameter identification and have not been widely adopted for practical use. In this paper we introduce a relatively simple modification of the well‐known critical state model which accounts reasonably well for the phenomena observed under cyclic tests and indeed improves the performance of critical state, models in monotonic loading.This model is compared with experimental results and with the ‘densification model’ introduced earlier by the authors and shows good predicitive capacity.The model is of a generalized plasticity‐bounding surface type. In its simplest form, suitable for clay‐like materials, it requires the identifications of a single parameter additional to those required for a standard, critical state model.
Two‐dimensional consolidation analysis using an elasto‐viscoplastic constitutive equation
Authors: Oka F. , Adachi T. , Okano Y. 
Published: August 2005

AbstractA two‐dimensional consolidation analysis of clay deposits was made with an elasto‐viscoplastic constitutive model and Biot's consolidation theory. One‐ and two‐dimensional consolidation problems were analysed numerically by the finite element and finite difference methods. Results show that the proposed method can describe the effect of sample thickness and aging on consolidation phenomena. The two‐dimensional behaviour of a clay foundation during the construction of embankments also was simulated.
Three‐dimensional analysis of a pile‐group foundation
Authors: Muqtadir A. , Desai C. S. 
Published: August 2005

AbstractA non‐linear three‐dimensional finite element procedur is developed and applied for the analysis of pile group foundations. The numerical procedure allows for elastic, non‐linear elastic and elastic‐plastic hardening behaviour of sand. In order to include the interaction effects involving relative slip and debonding, the thin‐layer interface element is used. The predictions for displacements and loads obtained from the numerical procedure are compared with laboratory model test results of a pile group. Displacements, stresses and forces distribution in various components of the pile group are also examined. Furthermore, the effects of the non‐linear soil response and relative motions at the interface are indentified and discussed.
An analytical solution to the design of precast concrete pavements
Authors: Bull John W. 
Published: August 2005

AbstractPrecast concrete pavement units are used in areas with low subgrade CBR values and high static and dynamic loadings. Unlike flexible pavements and rigid pavements, there are no design charts from which pavement engineers can design precast concrete pavements. The author has investigated analytically the relative importance of the factors affecting the ultimate stress and subgrade bearing pressures in precast concrete pavements. Presenting the results in graphical form, the design charts are used toillustrate the new design method.
Limits to the Jaumann stress rate
Authors: Molenkamp F. 
Published: August 2005

AbstractIn this paper it is shown that the Jaumann stress rate is not accurate for moderate deformations with deviatoric strains of more than 10 per cent; in such cases the objective stress rate is better calculated using the material rotation rate as calculated by polar decomposition. For very large deformations of granular materials this approach becomes invalid too because then the fabric tends to rotate together with principal stresses. Apparently in general the fabric rotation of a granular material cannot be described by continuum mechanics alone. For the numerical calculation of the material rotation for moderate deformations a numerical subroutine, based on polar decomposition, has been developed.
A hybrid boundary element‐finite element analysis procedure for fluid flow simulation in fractured rock masses
Authors: Elsworth D. 
Published: August 2005

AbstractExtension of numerical techniques to the analysis of fissure flow in three‐dimensional rock masses of realistic complexity and extent constitutes an important facility in civil engineering and resource exploitation practice. Migration velocities of contaminants and fluid discharge will always be higher for a true three‐dimensional network over a two‐dimensional representation in that the effect of critical, out‐of‐plane intersections may be correctly accommodated. Revised direct boundary element formulations are developed that are capable of discretizing individual fissure discs and their intersections with adjacent fissures. Discretization coverage, by definition, is limited to the fissure edges and internal intersections, with this factor alone being a major advantage of the technique over the more conventionally utilized domain methods. Appropriate manipulation of the resulting set of equations is shown to yield a fully populated, positive definite, symmetric tensor representing the geometric conductivity of a single fissure disc. The retained degrees‐of‐freedom for the ‘super element’ are purely in terms of the fissure intersections with a minimum of 1 degree‐of‐freedom required per intersection. Global matrix assembly and solution is accomplished by standard finite element techniques, the global matrix being, in general, sparsely populated. The procedure is ideally suited to micro‐computer solution in that a reduced degree‐of‐freedom system is obtained from a much larger and computationally, intractable system. The advantages of boundary solution procedures are realized with minimal data input requirements and effective representation of high potential gradients. The sparsely populated and symmetric from of the global matrix retains one of the more favourable assets of the secondary finite element formulation.
Constants for an elastic–plastic cap model for limestone
Authors: Chu H. S. , Brandt H. 
Published: August 2005

AbstractTriaxial fracture tests with overburden pressures ranging from 0.69 to 136 MPa were performed to determine the material parameters involved in a cap model for limestone. Three material parameters A, B and C, were evaluated through Powell's optimization method and the remaining parameters through simulation‐curve fitting procedure. The resulting cap model was tested against separate triaxial fracture and hydrostatic compression tests. Modification of the original hardening function, as proposed by DiMaggio and Sandler, provided an improved fit for the experimental data.
Modelling of sand behaviour under earthquake excitation
Authors: Pietruszczak S. , Stolle D. F. E. 
Published: August 2005

AbstractIn this paper, liquefaction potential of loose sand deposit subjected to an earthquake loading is evaluated. The analysis is performed by using a finite element technique incorporating the equations of dynamics of saturated porous elastoplastic media. The soil response is modelled by an anisotropic hardening rule, similar to that as proposed by Poorooshasb and Pietruszczak.1 The concept is based on the theory of bounding surface plasticity incorporating a non‐associated flow rule and the idea of reflected plastic potential. The present paper provides a modified formulation to that discussed in Reference 1. Modifications are aimed at simplifying the concept for numerical implementations.
A nonlinear programming analysis of unconfined steady‐state seepage
Authors: Gioda Giancarlo , Gentile Carmelo 
Published: August 2005

AbstractA finite element, variable mesh analysis of unconfined steady‐state seepage problems is presented based on a nonlinear programming algorithm. It is shown that the minimization of an objective function which merely represents a measure of the total flux leaving or entering the mesh at the free surface nodes (except those that belong also to pervious boundaries) does not permit a unique definition of the free surface geometry. This problem, which is apparently related to the numerical instabilities often met when using variable mesh approaches, can be eliminated by adding to the objective function a term representing a sort of overall ‘regularity’ condition for the shape of the free surface. The modified solution procedure turns out to be stable and able to provide meaningful results for practical problems even when rather coarse meshes are adopted.
Response of pile groups subjected to lateral loads
Authors: Leung C. F. , Chow Y. K. 
Published: August 2005

AbstractAn approach is presented for the prediction of linear and nonlinear load–deformation behaviour of laterally loaded pile groups. The individual pile response is obtained by the conventional p–y curve technique, while group interaction is modelled using the Mindlin's solution. Good agreement is observed when comparing the present method of analysis with the commonly used interaction factor approach for the computation of response of pile groups embedded in a homogenous, isotropic elastic half‐space. The predicted pile group behaviour also compares favourably with existing field data on laterally loaded pile groups in soft clay.
Boundary element elastic analysis of layered soils by a successive stiffness method
Authors: Maier G. , Novati G. 
Published: August 2005

AbstractThe elastostatic analysis of layered systems (such as a soil consisting of a set of L individually homogeneous strata) is tackled here on the basis of discretized boundary integral equations (boundary element method). By exploiting the peculiar chain‐like pattern of the system, a recursive formula is obtained which generates economically a ‘stiffness matrix’ of the first n layers (from bottom) at the upper interface with the subsequent layer (n = 1…L). The ‘successive stiffness’ method proposed is shown to imply noteworthy advantages with respect to both the standard boundary element method by zones (or subregions) and another ad hoc, earlier method resting on a boundary element approach combined with the transfer matrix concept. This conclusion is corroborated by two‐dimensional examples.
Viscoplastic model for geologic materials with generalized flow rule
Authors: Desai C. S. , Zhang D. 
Published: August 2005

AbstractThe general yield function in the hierarchical approach for constitutive modelling of materials is used with Perzyna's theory to characterize viscoplastic behaviour of geologic materials: a sand and rock salt. Particular attention is given to determination of the constants from laboratory quasistatic or short term, and creep tests. The proposed model is verified with respect to observed laboratory response of the sand and salt. It is implemented in a non‐linear finite element procedure and applied to analyse time‐dependent behaviour of a cavity in the rock salt.
Axial and lateral response of pile groups embedded in nonhomogeneous soils
Authors: Chow Y. K. 
Published: August 2005

AbstractA numerical method of analysis based on elasticity theory is presented for the analysis of axially and laterally loaded pile groups embedded in nonhomogeneous soils. The problem is decomposed into two systems, namely the group piles acted upon by external applied loads and pile–soil interaction forces, and a layered soil continuum acted upon by a system of pile–soil interaction forces at the imaginary positions of the piles. The group piles are discretized into discrete elements while the nonhomogeneous soil behaviour is determined from an economically viable finite element procedure. The load–deformation relationship of the pile group system is then determined by considering the equilibrium of the pile–soil interaction forces, and the compatibility of the pile and soil displacements. The influence of soil nonlinearity can be studied by limiting the soil forces at the pile–soil interface, and redistributing the ‘excess forces’ by an ‘initial stress’ process popular in elasto‐plastic finite element analysis. The solutions from this approach are compared with some available published solutions for single piles and pile groups in homogeneous and nonhomogeneous soils. A limited number of field tests on pile groups are studied, and show that, in general, the computed response compares favourably with the field measurements.
Interaction between torsional and axial pile responses
Authors: Georgiadis Michael 
Published: August 2005

AbstractThe effect of axial load on the torsional pile response and the effect of torque on the axial pile response are investigated. To perform this investigation, a computer program was developed which uses the transfer matrix method to analyse a pile supported by a series of coupled axial and torsional elasto‐plastic springs. The study indicated that the ultimate torsional and axial pile capacities, as well as the axial displacements and rotations, are significantly affected by the combined load action.
Multi‐laminate framework of soil models—plasticity formulation
Authors: Pietruszczak S. , Pande G. N. 
Published: August 2005

AbstractThis paper presents plasticity formulation of the multi‐laminate framework of soil models. Soil element is assumed to be an assemblage of perfectly fitting polyhedral blocks and irreversible deformations are assumed to occur due to sliding, separation/closing of the boundaries. Using an appropriate summation of mechanisms, the total plastic strains are obtained by evaluating contributions from an infinite number of randomly oriented planes in space. The paper provides a general plasticity formulation and examines various constitutive theories which can be incorporated into the framework.