bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic stability analysis of undrained simple shear on water‐saturated granular soils
Authors: Vardoulakis I. 
Published: August 2005

AbstractDynamic stability of undrained, simple‐shear deformations on water‐saturated granular soil specimens is discussed. The soil is described by a 2D‐flow theory of plasticity for frictional and dilatant material. Contractant material becomes unstable (liquefies) at the state of maximum shear stress, whereas dilatant material becomes unstable after the state of maximum effective stress obliquity is reached in the softening regime of the background drained behaviour. In both cases the correct evolution equations for the growth coefficient of the instability are derived and compared with the results of the inertia‐free formulation of the problem.
Dynamics of fluid‐saturated soils—variational formulation
Authors: Sandhu Ranbir S. , Hong Soon J. 
Published: August 2005

AbstractVariational principles governing dynamics of fluid‐saturated linear elastic porous media are derived. Complementary as well as direct formulations are discussed. Discontinuities in the field variables, the approximation space and the excitation are allowed for. Extensions of the variational principles to relax smootheness requirements on certain field variables are introduced along with some specizalizations convenient for finite element applications.
A method of computing the consolidation behaviour of layered soils using direct numerical inversion of Laplace transforms
Authors: Booker J. R. , Small J. C. 
Published: August 2005

AbstractA method is presented for obtaining the consolidation behaviour of a layered soil subjected to strip, circular, or rectangular surface loadings, or subjected to fluid withdrawal due to pumping. The solution method involves applying a Fourier or Hankel transform to the field quantities along with a Laplace transformation. The effect of the Fourier or Hankel transform is to reduce a two‐ or three‐dimensional problem or one involving axial symmetry, to one involving only a single spatial dimension. In cases where the soil is horizontally layered, this has great advantages over conventional methods, such as finite element or finite difference methods, since very little computer storage and data preparation time is required. Solution of the time dependent problem is achieved by applying a Laplace transformation to the field variables, obtaining solutions in Laplace transform space, and then numerically inverting the transformed solutions to obtain the real time behaviour. This eliminates the need for ‘marching type’ schemes where a solution is found from one at a previous time. By direct inversion of the Laplace transform, a solution may be obtained directly at any given time.
Shakedown in frictional materials under moving surface loads
Authors: Collins I. F. , Cliffe P. F. 
Published: August 2005

AbstractElastic/plastic deformations in frictional materials under moving surface loads are investigated. The static and kinematic shakedown theorems are used to obtain estimates of the critical shakedown load for plane strain deformations under trapezoidal surface load distributions and for three‐dimensional deformations under loads distributed over circular areas. It is shown that the material can fail either by incremental collapse or in cyclic or alternating collapse modes.
A method of time‐dependent analysis using elastic solutions for nonlinear materials
Authors: Chua Koon Meng , Lytton Robert L. 
Published: August 2005

AbstractThe formulation of viscoelastic solutions from elastic equations using the ‘correspondence principle’ and an inverse Laplace transform has been discussed extensively in the literature. Because this method has been developed, many time‐dependent solutions can be obtained from closed form elastic solutions and conditions have been delineated in which the ‘quasi‐elastic’ approximation of the viscoelastic solution is within acceptable tolerance. This communication shows the feasibility of the application of these methods to formulate approximate nonlinear viscoelastic solutions with nonlinear stress‐strain materials, and for want of a specific nonlinear model to demonstrate this, the hyperbolic model was selected. The ‘power law’ is used to model the relaxation modulus of the viscoelastic materials. There are five related development that are discussed here using a simple numerical example to illustrate each of them and they are: (1) a linear elastic solution, (2) a linear viscoelastic solution, (3) a nonlinear elastic solution, (4) a nonlinear viscoelastic solution and finally, (5) a ‘regression’ approximation of the nonlinear viscoelastic solution which is suggested by the series form of the elastic solution. All of these are related to one another and each provides an acceptably accurate solution of the problem it addresses. The latter is of particular practical interest since it can be used to provide answers to problems involving nonlinear viscoelastic materials while requiring only very small calculation times. The problem used as an example is the calculation of the displacement of a circular hole in an infinite plate made of a material with a nonlinear time‐dependent stress‐strain relationship. The nonlinear elastic form of the solution was developed by matching results from nonlinear finite element analysis.
Rapid evaluation of the critical slip surface in slope stability problems
Authors: Li K. S. , White W. 
Published: August 2005

AbstractExisting approaches for locating the critical slip surfaces are briefly reviewed. A number of techniques and strategies are proposed whereby the efficiency and robustness of some of the existing approaches can be enhanced. A new solution scheme is also developed for rapid calculation of the factor of safety. The new solution scheme requires only one level of iterations in contrast to the conventional solution scheme which invoives two levels of iterations. It is also applicable to a variety of stability models. A new compound iterative procedure is developed whereby the factor of safety can be calculated to a high accuracy within a few iterations. This reduces greatly the total computer time required for locating the critical slip surfaces.
Parameter identification in a damage model for rock mechanics
Authors: Resende L. , Martin J. B. 
Published: August 2005

AbstractAttention is focused on the mechanical behaviour of rock‐like materials. Developments and applications of a constitutive model based on damage theory are presented. The internal damage model is calibrated for a hard brittle rock, Bushveld Norite, and through this process the identification of the material parameters is carried out. Emphasis is placed on the identification of the material parameters in the damage evolution law. The uniqueness of solutions in the softening regime is investigated through finite element mesh sensitivity studies of non‐uniform deformation triaxial compression tests.
Bifurcations in finite element models with a non‐associated flow law
Authors: De Borst R. 
Published: August 2005

AbstractA numerical approach to bifurcation problems in soil mechanics is described. After locating the bifurcation point by a combination of an incremental‐iterative loading procedure and an eigenvalue analysis of the tangent stiffness matrix, the solution is continued on the localization path by a suitable combination of the fundamental solution and the eigenvector belonging to the lowest eigenvalue. The procedures are applied in a bifurcation analysis of a cohesionless soil in a biaxial testing device. The results suggest that a diffuse bifurcation mode with a short wavelength is encountered whereupon a shear band gradually develops. The inclination angle of the shear band compares well with analytical formulae and with empirical data.
Modelling and simulation of load transfer in reinforced soils: Part 1
Authors: Juran I. , Guermazi A. , Chen C. L. , Ider M. H. 
Published: August 2005

AbstractResults of both triaxial and direct shear tests on reinforced soil samples performed by different investigators have shown that soil dilatancy and extensibility of the reinforcements have a significant effect on the generated tension forces in the inclusions. An appropriate soil‐‐reinforcement load transfer model, integrating the effect of soil dilatancy and reinforcement extensibility is therefore needed to adequately predict forces in the inclusions under expected working loads. This paper present a load transfer model assuming an elastoplastic strain hardening behaviour for the soil and an elastic‐‐perfectly plastic behaviour for the reinforcement. This model is used to analyse the response of the reinforced soil material under triaxial compression loading. A companion paper present the application of this model for numerical simulations of direct shear tests on sand samples reinforced with different types of tension resisting reinforcements. The model allows an evaluation of the effect of various parameters such as mechanical characteristics and dilatancy properties of the soil, extensibility of the reinforcements, and their inclination with respect to the failure surface, on the development of resisting tensile stresses in the reinforcements. A parametric study is conducted to evaluate the effect of these parameters on the behaviour of the reinforced soil material. An attempt is also made to verify the proposed model by comparing numerical predictions with available experimental results of both triaxial and direct shear tests on reinforced soil samples. This model can be used for analysis and design of reinforced soil walls with different types of tension resisting inclusions to predict tension forces under expected working loads.
Effects of voids and volume changes on the behaviour of frictional materials
Authors: Lade Poul V. 
Published: August 2005

AbstractDevelopment of constitutive models for engineering materials is often based on a framework of elasticity and plasticity theories as developed for metals. Prsented here is a review of some of the basic differences in the experimentally observed behaviour of metals and frictional materials. Two of the distinguishing characteristics between metals and frictional materials are the absence or presence of voids and the tendency to change or maintain constant volume during compression and shear. These differences must be recognized in order to develop reasonable constitutive models for frictional materials.
A three‐dimensional finite element program for brittle bimodular rock‐like materials
Authors: Khan Akhtar S. , Yuan Si 
Published: August 2005

AbstractThe present paper models the behaviour of bimodular materials (materials with different tensile and compressive moduli) by using a three‐dimensional finite element method. Since there is no explicit and definite expression for the shear modulus G of bimodular materials, the analysis starts with a 3 × 3 elasticity matrix in the principal stress coordinate system, and then uses a transformation from principal to Cartesian coordinates to obtain the 6 × 6 elasticity matrix. A corresponding iterative technique is proposed, and multiloading sequences in non‐proportionate loading—which need more iterations because of the non‐linear elastic property—are also discussed. Numerical examples are presented which show good agreement with analytical results.
Finite element analysis of strain localization in frictional materials
Authors: Leroy Y. , Ortiz M. 
Published: August 2005

AbstractNumerical examples are given which illustrate the poor performance of conventional finite elements in problems involving strain localization in frictional materials. In one of the cases investigated, that of granular media subjected to plane strain biaxial loading, isoparametric elements are seen to inhibit localization altogether. With these examples by way of motivation, the performance of a recently proposed finite element method in the context of strain localization in frictional materials is assessed, with particular emphasis on three‐dimensional problems. In passing, some issues pertaining to the post‐bifurcation response of biaxial specimens are examined. In particular, the numerical simulations suggest that the observed softening is a geometrical effect not attributable to constitutive behaviour.
Consolidation around a heat source buried deep in a porous thermoelastic medium with anisotropic flow properties
Authors: Savvidou C. , Booker J. R. 
Published: August 2005

AbstractA solution is derived for the heat flow and consolidation which occur when a heat source is buried deep in a porous thermoelastic soil having anisotropic flow properties. This solution is used to examine the pore pressure generation and dissipation near both point and cylindrical heat sources. An increase in temperature will tend to generate an increase in excess pore pressure. However, the pore water will tend to flow from regions of high excess pore pressure to regions of low excess pore pressure, and so consolidation will occur, and temperature‐generated excess pore pressures will tend to dissipate. Many natural soils exhibit horizontal layering and so have a higher horizontal than vertical permeability. It is shown that in soils the excess pore pressure generated by a heat source is significantly less than that in an isotropic soil having an equal vertical permeability.
The key blocks of unrolled joint traces in developed maps of tunnel walls
Authors: Shi Gen‐hua , Goodman Richard E. 
Published: August 2005

AbstractThis paper presents a general method of key block analysis for cylindrical surfaces with numerous real or statistically produced joint traces. General tunnel curves, analytically represented, are unrolled to yield a ‘developed view’ on which the joint traces are continuous curves. Then, using extended block theory, the maximum key block regions are delimited from the curved polygons of the unrolled joint trace map. The methods discussed here apply to a cylindrical tunnel of any shape in section and in any orientation, including inclined tunnels and shafts. The trace maps for which the method applies can be generated statistically, as described herein, or surveyed from real traces on exposed tunnel walls. A brief introduction to the basic theory about tunnel key blocks is provided here so that this paper can be understood without reference to other papers on block theory.
Fracture toughness of geomaterials
Authors: Siriwardane Hema J. , Layne Abbie W. 
Published: August 2005

AbstractAn understanding of the fracture mechanics of geomaterials is important for the solution of many problems in geomechanics. One of the most important material properties involved in fracture mechanics is the fracture toughness, KIc. The short‐rod test configuration proposed by Barker1 has significant potential for becoming a standard test for fracture toughness determination in geomechanics. The purpose of this brief is to examine the application potential of the short‐rod test for geomechanics problems.
Numerical simulation of excavation in elastoplastic soils
Authors: Borja Ronaldo I. , Lee Seung R. , Seed Raymond B. 
Published: August 2005

AbstractA finite element method for simulating excavation in elastoplastic soils which produces a ‘unique’ solution for any number of excavation stages is presented. The proposed method satisfies the uniqueness principle for elastic materials postulated by Ishihara,1 and degenerates to the methods presented in the ADINA code2, 3 and by Brown and Booker4 and Ghaboussi and Pecknold5 for the simple elastic cases. The non‐linear (elastoplastic) finite element equations are derived from a variational formulation which accounts for time‐varying problem domain and boundaries. The roots of these non‐linear equations are solved by Newton's method, using the notion of the consistent tangent operator proposed by Simo and Taylor6 in conjunction with a numerical algorithm based on the ‘radial‐return’ concept for integrating stresses.7–9 Numerical examples demonstrate that in the elastic case the solution to problems involving a ‘shrinking’ (excavation) or ‘expanding’ (fill) domain is superposable and does not depend on the number of construction stages. For a monotonically shrinking elastoplastic domain and the von Mises and Drucker—Prager yield models, it is shown that the proposed method also produces a ‘unique’ solution independent of the number of excavation stages. Finally, the asymptotic quadratic convergence exhibited by the proposed method is demonstrated to show the efficiency engendered by the technique described.
On hypo‐elastic analogues of the dilatant double‐sliding model
Authors: Kruyt N. P. 
Published: August 2005

AbstractThe relation between the hypo‐elastic constitutive law and Mehrabadi and Cowin's dilatant double‐sliding model for cohesionless granular materials is studied. Conditions that must be satisfied by hypo‐elastic analogues of the double‐sliding model are derived constructively, and a simple example is given.
Strain‐path analyses for arbitrary three‐dimensional penetrometers
Authors: Huang An‐Bin 
Published: August 2005

AbstractA numerical technique has been implemented to perform strain path analyses for arbitrary three‐dimensional (3D) penetrometers. The technique is based on that developed in aeronautical engineering for the calculation of incompressible potential flows about arbitrary 3D, non‐lifting bodies. It uses a source‐density distribution on the surface of the body and solves for the distribution necessary to make the normal component of fluid velocity zero on the boundary. The surface of a 3D body is approximated by a series of plane quadrilaterals, and the integral equation for the source density is replaced by a set of linear algebraic equations which are then solved for the source densities on the quadrilaterals. The displacements and strains are eventually derived based on these source densities. A series of strain‐path analyses have been performed for cone and flat dilatometer penetrations. Results show that the soil responses to these two types of penetrometers are fundamentally different.
Effects of geometrical and material properties on the vertical vibration of three‐dimensional foundations by BEM
Authors: Israil A. S. M. , Banerjee P. K. 
Published: August 2005

AbstractThe dynamic response of foundation is influenced by various mechanical properties of soil as well as the geometrical properties of the foundation. In this paper, the effects of Poisson's ratio and material damping, as well as the influences of aspect ratio and embedment depth on the dynamic stiffness of rectangular foundations are studied. Studies are also conducted to investigate the influence of the type of contact at the soil–foundation interface and the soil layer overlaying a half‐space. These studies were conducted using an advanced algorithm of the boundary element method incorporating isoparameteric quadratic boundary elements. Higher‐order elements (quadratic) were used since they can model the wavy nature of the dynamic problem accurately.
Probabilistic modelling of joint orientation
Authors: Kulatilake Pinnaduwa H. S. W. , Wu Tien H. , Wathugala Deepa N. 
Published: August 2005

AbstractObserved frequencies of joint orientations are subject to error due to sampling bias. This error should be corrected before statistical inference is made on the distribution of orientation. Corrections (weighting functions) are developed for sampling bias in orientation for finite joints of different sizes and shapes intersecting rectangular exposures. Chi‐square goodness‐of‐fit procedures available for hemispherical normal and bivariate normal distributions are modified to make them applicable for both raw data and data corrected for sampling bias. The aforementioned corrections and procedures were applied to a joint orientation cluster to study the effect of (a) joint orientation, (b) joint size and (c) joint shape, on the statistical distribution of the orientation. The influences of all these aforementioned factors were found to be significant. However, at present, joint sizes and shapes are not measured in field joint surveys. Therefore, it is suggested to make attempts to obtain joint sizes and shapes in field joint mapping surveys. Since the currently available probability distributions are not adequate to represent all joint orientation distributions, it is suggested either to look for new probability distributions or to develop procedures to use empirical distributions in modelling orientation distributions.
Stress and couple stress in a layered half plane with surface loading
Authors: Mühlhaus Hans‐Bernd 
Published: August 2005

AbstractIn this paper the stress and moment stress distribution in a periodically layered half plane due to an arbitrary surface loading are derived. The bending stiffness of each layer is considered within the framework of Cosserat's continuum theory. Special emphasis is given to the case when the shear modulus of the one type of layer is much smaller than that of an adjacent layer. Results are illustrated for the case of a strip loading.
Finite element analyses of soil plug response
Authors: Leong E. C. , Randolph M. F. 
Published: August 2005

AbstractOpen‐ended pipe piles are often used in offshore foundations. The response of the soil plug inside a pipe pile is poorly understood, and only limited work has been performed to quantify the response under the different loading conditions relevant to offshore platforms. This paper describes numerical analyses that have been carried out in order to assess the end‐bearing capacity of the soil plug under loading conditions which range from undrained to fully drained. The soil plug has been modelled as either elastic, elastic–perfectly‐plastic or elastoplastic. The soil–pile interface, an important aspect of the problem, has been examined critically. Comparison with experimental data from model test at laboratory scale indicates that the load–deformation behaviour of the soil plug is modelled well using an elastoplastic model for the soil plug, and an elastic–perfectly‐plastic joint element to model the soil–pile interface. The finite element analyses show that, under typical loading conditions, adequate end bearing may be mobilized by the soil plug, largely by high effective stresses in the bottom 3–5 diameters of the soil plug.
Theory of the collapsed zone at the front of a coal seam and its effect on translatory rock bursting
Authors: Lippmann H. 
Published: August 2005

AbstractIf the slope of the uniaxial stress–strain diagram in the post‐failure regime is steep enough, it is shown, using a simplified (‘elementary’) theory, that the frontal zone of a coal seam close to a cavity may suddenly collapse. This collapse, well known from in situ, evidence, is also shown to reduce in most cases the danger of initiation or the strength of a subsequent coal mine bump.
A thermomechanical analysis of the G‐Tunnel heated block experiment using a compliant‐joint rock‐mass model
Authors: Costin L. S. , Chen E. P. 
Published: August 2005

AbstractThe results of two‐dimensional finite element analyses of several thermal/mechanical loading cycles of the G‐Tunnel heated block experiment are presented. The deformations of the block resulting from thermal loading under constant biaxial stress were determined using a recently developed compliant‐joint rock‐mass model. The results of the finite element calculations were compared to experimental results reported by Zimmerman et al. Qualitative agreements between the experimental and numerical results were obtained in all cases while quantitative agreements were achieved in some cases. The results of this evaluation are discussed.