bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of flow properties of expansive clays
Authors: Uzan J. , Lytton R. L. 
Published: August 2005

AbstractThe paper deals with the determination of the flow properties of expansive and unsaturated clays under different conditions of stress. By choosing the moisture content as the dependent variable, the well known non‐linear diffusin equation is derived. Numerical solutions using a finite element program are presented, assuming a linear relationship between the moisture diffusivity and the concentration (the relative moisture content). These solutions are interpreted and a procedure is proposed to derive the flow properties of the clay from the sorption curves. Results of tests are presented and used to illustrate the procedure. It is found that the lower the stress applied, the smaller the initial moisture diffusivity and the stronger the dependence of the moisture diffusivity upon the concentration.
Formation of shear bands in sand bodies as a bifurcation problem
Authors: Vardoulakis I. , Goldscheider M. , Gudehus G. 
Published: August 2005

AbstractThe paper reports on the results of theoretical and experimental investigations on the spontaneous formation of shear bands in sand bodies. The phenomenon is considered as a bifurcation problem. Consequently, material response and configuration‐dependent loading determine the bifurcation mode. Both Coulomb's and Roscoe's solutions of inclination of the shear band can be correct theoretically and experimentally. The first one holds for non‐rotating stress axes, the second one for co‐rotating stress and strain increment axes during failure. Values in between can occur if the rotation of principal stress axes is not equal to one of these limits. If Coulomb's inclination of shear band occurs, there is a thin deforming material layer separating rigid bodies. Inside the shear band non‐coaxiality of strain increment and stress holds from the beginning. If Roscoe's inclination of shear band occurs, it is separating two deforming bodies. Inside the shear band strain increment and stress are coaxial at peak.
Plates on saturated porous elastic foundations
Authors: Tabaddor Farhad 
Published: August 2005

AbstractThe problem of plates on consolidating soil is considered. Biot's three‐dimensional consolidation theory, the generalization of Terzaghi's model, is employed to account for the consolidation process. A mathematical model is developed and the differential equations governing the system together with the proper boundary conditions are derived. A variational formulation of the problem and a convenient approximate method of solution are also presented.For numerical analysis, the problem of a rectangular plate on consolidating soil under various loading conditions is numerically solved and the effects of various physical factors on the settlements and the pore pressures are studied.
Axisymmetric compression of a Mohr–Coulomb medium around a circular hole
Authors: Florence A. L. , Schwer L. E. 
Published: August 2005

AbstractAn analytical solution is presented for the stress and strain fields in a Mohr–Coulomb material in plane strain around a circular hole when it is compressed by an axisymmetric far‐field pressure. It is shown that several solutions arise involving one to three plastic zones depending on the values of Poisson's ratio and the friction angle. The solution chosen for presentation was obtained and used to validate the functioning of the Mohr–Coulomb yield condition that was added to the NONSAP finite element code. Stress and strain field comparisons are made.
Surface settlement of a finite elastic layer whose modulus increases linearly with depth
Authors: Brown P. T. , Gibson R. E. 
Published: August 2005

AbstractAn examination has been made of the behaviour of a finite layer of elastic material of constant Poisson's ratio, whose Young's modulus increases linearly with depth, and which rests on a rough rigid base. Values of surface settlement at the corner of a rectangular area of uniform loading are presented for values of Poisson's ratio of \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{1}{2} $\end{document}, \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{1}{3} $\end{document} and 0, and for wide ranges of degree of inhomogeneity and loading breadth to depth ratio.
Numerical analysis of rafts on visco‐elastic media using eigenvector expansions
Authors: Brown P. T. , Booker J. R. 
Published: August 2005

AbstractProblems of a raft on a visco‐elastic continuum may be converted to equivalent elastic problems by means of a Laplace transformation. In this paper a numerical solution of the equivalent problem is obtained by finite element or other techniques. This solution is converted into the form of an eigenvector expansion and then transformed into a numerical solution to the original problem by inverting the Laplace transform. This form of solution has the advantage of applying to any visco‐elastic model, and of requiring little additional computation as a result of changing the visco‐elastic model, the relative raft‐soil stiffness or the load pattern.The application of the method is illustrated by results for circular rafts, strip footings of finite length and rectangular rafts, and particular attention is paid to a realistic soil creep function which is asymptotic to a linear function of log time.
Theoretical study of hydraulically fractured penny‐shaped cracks in hot, dry rocks
Authors: Abé H. , Keer L. M. , Mura T. 
Published: August 2005

AbstractA simple and analytical method of solving the problem of heat extraction from a penny‐shaped crack having both inlet and outlet holes is developed by using a two‐dimensional flow model when fluid is injected at a constant flow rate. Temperature distributions in both rock and fluid are obtained by taking into account the hydraulic and thermal growth of the crack. The outlet fluid temperature and energy extraction rate versus time are shown by some illustrative examples. Although the effect of thermal, contraction of rock upon the crack width is large, its influence upon flow rate and crack tip stress intensity factor is sufficiently small within the first several years so that the crack radius can be determined mainly by the mechanical deformation of, the rock.
3D mine pillar design information from 2D FEM analysis
Authors: Pariseau W. G. , Sorensen W. K. 
Published: August 2005

AbstractThis paper described a technique for obtaining three‐dimensional mine design information using a two‐dimensional finite element program where the mining geometry consists of an extensive array of underground rooms and pillars. The technique is based upon a simple augmentation of forces in a two‐dimensional analysis to produce the same average pillar stress that would occur in a full three dimensional analysis. Detailed comparisons between a three‐dimensional analysis, a two‐dimensional analysis (plane stress and plane strain) and an augmented two‐dimensional analysis (also plane stress and plane strain) of stress about a typical coal mine pillar are presented. A local factor of safety is defined and then mapped over the pillar midplane, the immediate roof and immediate floor using the results from the full three‐dimensional analysis. Comparisons of roof and pillar safety factor distributions obtained by the three‐dimensional, two‐dimensional and augmented two‐dimensional analyses show that the minimum safety factors in the pillar (at the pillar sides) are predicted quite closely by the augmented two‐dimensional techniqe (plane stress). The same is true of the immediate roof, although the three‐dimensional safety factor tends to be higher in the roof (over the room) than that calculated by the augmented twodimensional technique. The augmented loading procedure appears to hold considerable promise as a very efficient and cost reducing techniqe for mine pillar design.
Finite element analyses of isotropic and anisotropic cohesive soils with a view to correctly predicting impending collapse
Authors: Toh C. T. , Sloan S. W. 
Published: August 2005

AbstractOne major problem encountered when using the finite element method to simulate the load–deformation behaviour of an elasto‐plastic soil mass is that the theoretical collapse load is generally exceeded, and in some cases the numerical solution fails to exhibit a collapse load. A mixed variational principle is used as the basis for developing the governing equations of deformation and the results from this are compared with those obtained from the use of the virtual power equation. The former is found to give improved results and is generalized to include description of finite deformation. An Eulerian frame of reference is used. The method of approximating configuration changes in the numerical solution procedure is found to determine the shape of the load–deformation curve. Finally, a simple method of accounting for anisotropy of yield is presented.
Numerical identification of soil‐structure interaction pressures
Authors: Gioda Giancarlo , Jurina Lorenzo 
Published: August 2005

AbstractA numerical approach is presented for the ‘identification’ (or back calculation) of the earth pressure acting on embedded or retaining structures. The procedure is applicable to structures of any shape and requires a set of in situ measurements that may include displacements of points on the structure, values of concentrated forces, values of distributed loads at some locations, etc. Possible limiting values of the unknown loads, non‐linear structural behaviour, varying accuracies of the input data are accounted for in the problem formulation. Depending upon the type of problem, the solution is reached by means of the unconstrained or constrained minimization of a suitably defined error function. As an example, the proposed approach is applied to the identification of the earth pressure acting on some typical geotechnical engineering structures.
Trap‐door problem with dry sand: A statical approach based upon model test kinematics
Authors: Vardoulakis I. , Graf B. , Gudehus G. 
Published: August 2005

AbstractThe trap‐door problem with dry sand is treated in a statical analysis based upon model test kinematics. Integration of the equilibrium conditions along horizontal slices and introducing the mean value for the vertical stresses yields a differential equation for the trap‐door force. Concerning the constitutive response of sand a statical model of a moving shear band is proposed as an internal boundary. Solutions for the trap‐door force for the active and passive modes and for the ultimate and residual states are discussed.
Numerical prediction of collapse loads using finite element methods
Authors: Sloan S. W. , Randolph M. F. 
Published: August 2005

AbstractIn this paper, the ability of a displacement‐type finite element analysis to predict collapse loads accurately is investigated. For the usual assumptions of ideal plasticity and infinitesimal deformations, attention is focused on undrained geotechnical problems. The theoretical criterion originally developed by Nagtegaal et al.1 is applied to each member of the serendipidity quadrilateral and triangular family of elements, up to and including those with a quartic displacement expansion. This method of assessing the suitability of a particular type of element is shown to be valid for any constitutive law which attempts to enforce the constant volume condition at failure, such as critical state type soil models. The method is also generalized to permit an assessment, a priori, of the suitability of any given mesh which is composed of a finite number of elements of the same type. It is postulated that the 15‐noded, cubic strain triangle is theoretically capable of accurate computations in the fully plastic range for undrained geotechnical situations which involve axial symmetry or plane strain. This prediction is verified by a series of numerical experiments on footing problems. Extending the work of Nagtegaal et al., 1 it is established theretically that if lower order finite elements are employed rigorously for non‐trivial undrained problems with axial symmetry, then it is impossible to predict the exact limit load accurately, regardless of how refined the mesh may be.
On statistical description of stress and fabric in granular materials
Authors: Mehrabadi M. M. , Nemat‐Nasser S. , Oda M. 
Published: August 2005

AbstractThe notion of overall macroscopic stress in granular masses is examined from a fundamental point of view by a statistical consideration of the contact forces that are transmitted by the contacting granules at the microscale. This examination leads in a natural way to relations between the macroscopic stress and the resulting granular fabric. The overall stresses are expressed in terms of the contact forces in two different but complementary ways: (1) by a statistical averaging over the sample volume of contact forces and “branches” which are vectors connecting the centroids of two contacting granules; and (2) by defining the overall tractions transmitted across an interior imagined plane as the sum of the contact forces which represent the mechanical effect of granules on one side of a unit area of this plane, upon those on the other side. Conditions under which the two representations of overall stresses are equivalent, are examined in detail. In addition, explicit results are given, which, define stresses in terms of the fabric and other microstructural characteristics of the granular mass.
Limit analysis: A linear formulation of the kinematic approach for axisymmetric mechanic problems
Authors: Turgeman S. , Pastor J. 
Published: August 2005

AbstractThis paper deals with a numerical formulation of the kinematic limit analysis method. This formulation, based on a finite element discretization, is available for axisymmetric cases. The linearization of the yield Tresca and Von Mises criteria leads to linear programming problems. The velocity fields described here are plastically admissible only on an average. The influence of this approximation is quantified for the triaxial test problem and the stability of circular excavations.
A mapping finite element method for stress calculation in two‐dimensions
Authors: Nath B. 
Published: August 2005

AbstractA mapping finite element method is proposed for the solution of elastic problems in two‐dimensions. This method, based on the logarithmic condensation of physical space, is found to give significantly greater accuracy than when the problem is solved in the physical plane using the standard FEM. Logarithmic condensation of space also permits the solution of large aspect‐ratio problems of this type, accurately and economically.
Finite layer analysis of consolidation. I
Authors: Booker J. R. , Small J. C. 
Published: August 2005

AbstractA method for the analysis of the consolidation of a horizontally layered soil under plane conditions is developed. The method depends upon the transformation of the governing equations by a Fourier trasform. This transformation has the effect of reducing the partial differential equations of consolidation to ordinary differential equations. The ordinary differential equations are then solved using a finite layer or finite difference approach. Once the solution in the transformed plane has been found, the actual solution is synthesized by Fourier inversion. The method leads to a considerable reduction in the amount of core storage necessary for solution and enables the solution of quite significant problems to be obtained on a mini‐computer.
A critical analysis of some variational methods in slope stability analysis
Authors: Castillo E. , Luceño A. 
Published: August 2005

AbstractDuring the last ten years the Calculus of variations technique has been applied to solve the problem of stability of slopes. All published methods are essentially based on the attainment of a functional and the search for its absolute minimum or maximum by vanishing its first variation.Obviously this statement of the problem is valid only if such a minimum or maximum exists and can be obtained by making the first variation of the functional equal to zero. So, these implicit hypotheses must be checked.This work analyses from this point of view the validity of the methods proposed by ‘Baker and Garber’, ‘Chen’ and ‘Castillo and Revilla’, and demonstrates that the first two methods are incorrectly stated while the third one is correct at least in the case of a frictionless soil.
Elasto‐plastic analyses of deep foundations in cohesive soil
Authors: Griffiths D. V. 
Published: August 2005

AbstractThe bearing capacity of deep foundations has been analysed using finite elements in conjunction with elasto‐viscoplasticity. The influence of elastic parameters, mesh size and strain conditions on computed collapse loads was observed. Axisymmetric problems in particular were of interst, because it was found that good numerical solutions could be obtained through to collapse provided reduced integration was used.
Shear vibration of vertically inhomogeneous earth dams
Authors: Gazetas George 
Published: August 2005

AbstractClosed‐form solution to the problem of free vibrations of vertically inhomogeneous earth dams, modelled as truncated‐wedge‐shaped shear beams, has been obtained by implementing an inverse procedure in which the determination of the function descrbing the inhomogeneity constitutes part of the problem. The resulting cube‐root variation of the shear‐wave velocity with distance from the crest compares very favourably with measurements in two Japanese dams. The results of the method are presented in theform of natural periods, modal shapes and average seismic coefficients for a number of truncation ratios. Compared with an ‘equivalent’ homogeneous dam, the inhomogeneous experiences sharper amplification of modal displacements and greater averge seismic, coefficients near the crest and has natural periods which are closer to each other. This behaviour is in better agreement with the observed response of a 37m‐high dam during five earthquake motions.
Consequences of deviatoric normality in plasticity with isotropic strain hardening
Authors: Baker R. , Desai C. S. 
Published: August 2005

AbstractFor many soils experimental evidence suggests that deviation from normality between the plastic strain increments and the yield function is exhibited mainly in the volumetric behaviour, whereas the deviatoric behaviour exhibits normality. An analysis of the consequence of this observation is presented, and it leads to an expression for the plastic potential function as composed of two functions, a yield function and another dependent only on the hydrostatic pressure; the latter is considered to constitute the concept of correction functions presented recently by Desai and Siriwardane13.
Analysis of rigid pavement on viscoelastic foundations subjected to moving loads
Authors: Bandyopadhyay Sudipta S. 
Published: August 2005

AbstractThe dynamic behaviour of road structure has been analysed by idealizing the subgrade with different viscoelastic models having three and four elements. Complex Fourier transformation has been used to solve the resulting differential equations. The results are presented in non‐dimensional form. A detailed study has been made to determine the effect of different parameters on the deflection and moment of the pavement. Also, the relative implications of idealizing the subgrade with different viscoelastic models have been studied. A numerical example has been solved.
Factors of safety and pile load tests
Authors: Baecher Gregory B. , Rackwitz Rüdiger 
Published: August 2005

AbstractThe factor of safety used in designing pile foundations for vertical load should depend on three things, prior information on load capacity summarized by empirical correlations with load capacity models, site specific information derived from load tests, and an objective function reflecting economic and safety considerations. A statistical approach to factor of safety selection was developed in order to suggest improvements of current standards for driven pile design. This approach recognizes a distinction between the variability of pile load capacity within individual sites, and the global variability upon which model correlations are based. Charts have been prepared for determining the FS required to achieve specified reliability indices, as a function of the number of load tests at a particular site and their outcomes.
Plasticity model for inherently anisotropic behaviour of sands
Authors: Ghaboussi Jamshid , Monen Hassan 
Published: August 2005

AbstractMost deposited sands exhibit anisotropic behaviour. A plasticity model has been proposed with the capacity for simulating such anisotropic behaviour. The proposed model contains a number of coefficients of anisotropy. Methodology for determination of the coefficients of anisotropy has been discussed. Using experimental data, the coefficients of anisotropy have been determined for a number of well‐known sands. Stress‐dilatancy has been modelled by using the ‘normalized work’ and it has been shown that the normalized work is independent of inherent anisotropy. Finally, some reasonably close comparisons between experimental results and model simulations have been reported.
Thin‐layer element for interfaces and joints
Authors: Desai C. S. , Zaman M. M. , Lightner J. G. , Siriwardane H. J. 
Published: August 2005

AbstractThe idea of using a thin solid element, called a thin‐layer element, in soil‐structure interaction and rock joints is proposed. A special constitutive model is used and various deformation modes such as no slip, slip, debonding and rebonding are incorporated. The shear stiffness is found from special laboratory tests and the normal stiffness is assumed to be composed of participation of the thin‐layer element and the adjoining solid elements. A parametric study shows that the thickness of the thin‐layer element can be such that the ratio of thickness to (mean) dimension of the adjacent element is in the range of 0.01 to 0.1. A number of simple and practical problems are solved to illustrate the success of the thin‐layer element for soil‐structure interaction problems.
Vibration of a homogeneous half‐space of arbitrary Poisson's ratio interrupted by a frictionless plane
Authors: Awojobi A. O. 
Published: August 2005

AbstractThe work presents an exact expression for the Hankel transform of the surface displacement of a rigid circular body performing harmonic vertical vibrations on a homogeneous elastic half‐space of arbitrary Poissn'S ratio interrupted at some depth by a frictionless horizontal plane. The limiting case of the uninterrupted half‐space is recovered in each of the extreme cases when the frictionless plane coincides with the surface or sinks to an infinite depth. Furthermore, the static case is derived in the limiting case of zero frequency and it is shown that the result agrees with the limiting case of zero gradient shear modulus variation for the static case of the incompressible non‐homogeneous half‐space.It is also established that Poisson'S ratio effect is linear, and the important proposition is again sustained that only surface shear modulus dominates vibrations on elastic media whereas any other factor such as the interruption of the frictionless plane as in the present case, merely constitutes a negligible secondary parameter.
An analytical solution for axisymmetric tunnel problems in elasto‐viscoplastic media
Authors: Fritz P. 
Published: August 2005

AbstractAn analytical solution is presented for the time‐dependent stresses and displacements in plane strain around a circular hole when it is loaded by an axisymmetric internal and far‐field pressure. The material is assumed to be elasto‐viscoplastic with dilatant plastic deformations according to a non‐associated flow rule. Strain softening is considered by a modified St. Venant slider which is characterized by Mohr‐Coulomb yield conditions for both the peak and the residual strengths.