bluuebunny/crossref_metadata_2025_split huggingface dataset:
Short‐crested wave‐induced soil response in a porous seabed of infinite thickness
Authors: Hsu J. R. C. , Jeng D. S. , Tsai C. P. 
Published: August 2005

AbstractWaves reflecting obliquely from structures establish short‐crested waves which are conducive to scour of the bed adjacent to them. The pore pressures and effective stresses induced by this wave system are derived analytically for an unsaturated, anisotropic soil matrix of infinite depth in a three‐dimensional domain. Verification is available by the solutions being readily reduced to the two‐dimensional cases of the progressive and standing wave, for which some closed‐form solutions are available. It is shown that wave obliquity is coupled with soil permeability. The effects of wave obliquity, relative water depth, soil stiffness and soil permeability on wave‐induced pore pressure are discussed in detail.
Fuzzy finite element analysis of a foundation on an elastic soil medium
Authors: Valliappan S. , Pham T. D. 
Published: August 2005

AbstractOne of the important factors that lead to errors in settlement predicitions is the degree of precision in obtaining the soil parameters. Most mathematical methods for reliability modelling offered to date in the area of geomechanics are based on the classical probabilistic approach, in which soil properties are treated as random variables. In this paper, a model based on the theory of fuzzy sets is presented to take account of the uncertainty in the soil behaviour. This proposed method considers the elastic modulus and Poisson's ratio as two fuzzy numbers in the elastic matrix. An example is given to show the possibility distributions of the displacements and the stresses at some locations in the soil medium. By means of a fuzzy inference scheme, the total possibility distributions or total membership functions of the finite element results may be obtained by considering the estimated error resulting from the mesh discretization.
On the description of localized deformation
Authors: Pietruszczak S. , Niu X. 
Published: August 2005

AbstractA mathematical framework for the description of localized deformation, as outlined in Reference 14, is reviewed. The formulation is derived by estimating the average mechanical properties of a medium intercepted by a shear band. The mechanical response of the homogenized system depends on the properties of the constituents and the respective volume fractions, it remains invariant however with respect to the thickness of the shear band. The implementation of the framework in the context of finite element analysis is discussed. Numerical examples, pertaining to some geotechnical problems, are provided.
Influence of relative density and stress level on the bearing capacity of sands
Authors: Simonini Paolo 
Published: August 2005

AbstractA finite element approach is presented to determine the bearing capacity of shallow footings on silica sand deposits. The approach can take into account the effects of relative density and stress level on the shear strength of granular soil and is applicable to a fairly large effective stress range. The strength of sand is characterized by a non‐linear Mohr–Coulomb criterion which depends on maximum and critical friction angles, widely used parameters in engineering practice. The results of analysis indicate that this approach yields reliable predictions of bearing capacity and, in particular, it can model the volumetric behaviour of the soil at failure.
A generalised D matrix for anisotropic elastic granular media
Authors: Du Jiang , Dusseault Maurice B. 
Published: August 2005

AbstractA matrix relating stress and elastic strain tensors for anisotropic particulate materials has been derived. The magnitude of the matrix depends on the state of the material anisotropy. Anisotropy in granular materials depends on strain because normal and tangential particle contact forces, as well as the spatial distribution of the contacts, vary with stress and strain. However, the rotation tensor and the strain tensor cannot be independent; they must satisfy certain constraints to meet the requirement for macroscopic stress tensor symmetry. These conditions and constraints lead to the derivation of the matrix presented in this article. The principal directions of the stress tensor and strain tensor are generally not coincident, and the values of deformation parameters, Young's modulus and Poisson's ratio, are direction dependent; these two aspects are also discussed in this paper. Whereas this matrix can be used in static numerical analyses for elastic problems, we note that this relationship can also be used as a basis upon which to derive a fully incremental stress–strain relationship for anisotropic granular materials in the plastic state, where the anisotropy is evolving with strain.
A fully coupled non‐linear dynamic analysis procedure and its verification using centrifuge test results
Authors: Muraleetharan K. K. , Mish K. D. , Arulanandan K. 
Published: August 2005

AbstractThe equations governing the dynamic behavior of saturated porous media as well as a finite element spatial discretization of these equations are summarized. A three‐parameter time integration scheme called the Hilber–Hughes–Taylor α‐method is used together with a predictor/multi‐corrector algorithm, instead of the widely used Newmark's method, to integrate the spatially discrete finite element equations. The new time integration scheme possess quadratic accuracy and desirable numerical damping characteristics. The proposed numerical solution and bounding surface plasticity theory to describe the constitutive behaviour of soil have been implemented as the computer code DYSAC2. Predictions made by DYSAC2 code are verified using dynamic centrifuge test results for a clay embankment. Importance of initial state of a soil on its dynamic behaviour is demonstrated.
Conformal analysis of seepage below a hydraulic structure with an inclined cutoff
Authors: Ijam Abbas Z. 
Published: August 2005

AbstractConformal mapping techniques are used to obtain an exact solution for seepage flow below a hydraulic structure founded on permeable soil of infinite depth for a flat floor with an inclined cut‐off at the downstream end. Results are presented for different values of b/s and θ. The exit gradient decreases considerably along a distance beyond the floor end with an increase in cut‐off inclination. The maximum exit gradient decreases for θ = 10, 20 and 30° and starts increasing for θ = 45°. The uplift pressure decreases as θ increases. It is concluded that using an inclined cut‐off increases the factor of safety in design against uplift and piping.
Elastoplastic analysis of jointed rocks using a coupled finite element and boundary element method
Authors: Xiao B. , Carter J. P. , Alehossein H. 
Published: August 2005

AbstractThis paper presents a coupled, elastoplastic, finite element and boundary element method for the two‐dimensional, non‐linear analysis of anisotropic jointed rock. The non‐linear and anisotropic behaviour of a jointed rock mass is simulated by representing the mass as an equivalent anisotropic, elastoplastic continuum, so that the influence of the jointing system is ‘smeared’ across the continuum, i.e. the individual joints are not modelled as discrete entities. Numerical examples have been solved to verify the capability, accuracy and efficiency of the present technique. The proposed technique has also been applied to the analysis of tunnel excavation problems in plane strain. The effects of anisotropy and non‐linearity of the jointed rock mass during excavation have been investigated in some detail.
A macroscopic elastoplastic constitutive law for multilayered media: Application to reinforced earth material
Authors: Pruchnicki Erick , Shahrour Isam 
Published: August 2005

AbstractThis paper refers to the formulation of a macroconstitutive law for elastoplastic multilayered media, using both thermodynamical approach and homogenization procedure. The latter shows that both the microstress and strain tensors are constant in each constituent. This result permits the formulation of a macroconstitutive law involving the microplastic strains as internal parameters. Both the macrofree energy and dual dissipation potential are computed and used to derive explicit expressions for the macrocompliance tensor, yield surface and hardening rule. Finally, this law is used to analyse the behavior of a reinforced earth material under various loading paths.
A numerical analysis of the foot‐floor interaction in long wall workings
Authors: Cristescu Nicolae , Ionescu Ioan R. , Rosca I. 
Published: August 2005

AbstractA mathematical and numerical approach for the description of creep and failure of coal around a longwall is given. Two coal strata are considered. They are assumed to be elasto‐viscoplastic. The variation in time of the stress and displacement around the excavation, as well as the limit thickness of the upper stratum which would avoid failure was found.
Prediction of pile capacity from stress‐wave measurements: A neural network approach
Authors: Chow Y. K. , Chan W. T. , Liu L. F. , Lee S. L. 
Published: August 2005

AbstractA neural network approach for the prediction of pile bearing capacity by the stress‐wave matching technique is presented. The main advantage of this approach over the traditional manual or automated matching approach is that it avoids the time‐consuming process of iterative adjustment. This makes it feasible to determine the static pile capacity in real time in the field. Another benefit of this approach is that as more case histories become available, the neural network can be improved by learning from these new examples.A three‐layer back‐propagation network is set up to illustrate the capability of the proposed approach for 70 dynamically tested concrete bored piles. A wave equation model developed at the National University of Singapore and coded in the NUSWAP computer program is used to formulate the problem. Up to 14 of the 70 piles (20 percent) are used in training the network. The NUSWAP program is used to generate simulation training examples based on the manually fitted training examples for further training of the network. Different network configurations are examined. The trained network produces results exhibiting good stress‐wave matching qualities compared to those obtained by manual fitting. The pile bearing capacities predicted by the two approaches agree very closely. The load‐settlement curve and axial load distribution in the pile computed using the network‐predicted soil parameters are in good agreement with the field measurements obtained from a maintained load test.
Dynamic response of an elastic and viscoelastic full‐space to a spherical source
Authors: Jiang J. , Blair D. P. , Baird G. R. 
Published: August 2005

AbstractThe dynamic response due to a spherical source of radius a embedded in an elastic and viscoelastic full‐space is investigated at a distance R from the source. Previous solutions to the elastic case are extended to incorporate realistic source pressure functions. The elastic solution is then cast in a scale independent form in order to generalize the application. The results show that the near‐field of the spherical source may be defined by R/a < 5. For this region the particle velocity and displacement decrease as R−2, and the risetime decreases as R−1. However. in the far‐field region (R/a > 5) the particle velocity and displacement decrease as R−1, and the risetime is independent of R. A non‐constant Q model is developed to model viscoelastic attenuation and a complete analytical solution for wave propagation is obtained by cascading the separate mechanisms of geometric attenuation and viscoelastic attenuation. A comparison of our analytical model with the results of dynamic finite element modelling shows excellent agreement. This suggests that the method of cascading the separate transfer functions is a valid approach for wave propagation in viscoelastic media.
Numerical simulation of the convergence of a bolt‐supported tunnel through a homogenization method
Authors: Bernaud D. , De Buhan P. , Maghous S. 
Published: August 2005

AbstractThe present paper describes the numerical implementation of constitutive relationships previously developed for modelling the elastoplastic behaviour of bolted rockmass regarded as a homogenized anisotropic medium on the macroscopic scale. Attention is more particulary focused on the iterative algorithm involved in such a numerical method, which makes use of projection formulas onto the yield surface. Those formulas are made explicit in the case of a purely cohesive rock material obeying a von Mises yield condition with associated flow rule. Combined with a finite element code, the proposed numerical procedure is then carried out for simulating the advancement of a bolt‐supported tunnel and calculating its convergence as the excavation proceeds. The results of this numerical simulation prove to agree perfectly well with those derived from an analytical model, thus validating the proposed numerical scheme. A quantitative study, varying some relevant parameters of the problem (bolt density, length of bolts, delay of placement behind the tunnel facing), is finally undertaken. It points to the versatility of the numerical approach, whose range of applicability can be further extended to various kinds of geotechnical structures reinforced by regularly distributed inclusions.
Magnetoelastic shear waves in an infinite self‐reinforced plate
Authors: Chattopadhyay A. , Choudhury S. 
Published: August 2005

AbstractThe propagation of magnetoelastic shear waves in an infinite self‐reinforced plate is studied in this paper. The frequency spectrum for SH‐modes in the plate is drawn and it is shown that if the dimensionless wave number is real, the branches are hyperbolas while for imaginary wave numbers, they are ellipses. It is also observed that for higher modes, the dimensionless group velocity approaches 9·9754 as the wave number increases. The group velocity is normalized with respect to the phase velocity of shear waves.For a homogeneous and isotropic medium, on the other hand, the dimensionless group velocity approaches unity. So it is approximately 10 times larger in case of magnetoelastic shear waves in an infinite self‐reinforced plate.It is also noted that in a reinforced medium, if both the values of the coupling parameter and the angle at which the wave crosses the primary magnetic field are increased, the values of the dimensionless frequency and group velocity are decreased.
Modelling transient heat and moisture transfer in unsaturated soil using a parallel computing approach
Authors: Thomas Hywel Rhys , Li Chi Leung Welkin 
Published: August 2005

AbstractA parallel numerical model, employing a finite difference explicit scheme for the analysis of coupled heat and moisture transfer in unsaturated soil, is employed to simulate a laboratory experiment of heating of medium sand. The model, written in a two‐dimensional polar co‐ordinate formulation, is programmed in the concurrent language Occam and executed on a parallel computing network of transputers. Parallelization is adopted as a means of overcoming computing difficulties, which limited numerical solutions to those at steady state, to enable transient behaviour to be simulated.The parallel algorithm was found to be very efficient, enabling a full solution of transient behaviour to be obtained. An investigation of the ability of the model to accurately simulate the complex, interrelated coupled nature of both two‐dimensional transient and steady‐state behaviour yielded very good correlation between experimental and numerical results. It can therefore be concluded that overall the results obtained provide confidence in the validity of the approach proposed.
An analytical solution for the transient response of saturated linear elastic porous media
Authors: Gajo A. , Mongiovi L. 
Published: August 2005

AbstractThe motions of fluid and solid phases in saturated porous media are coupled by inertial, viscous and mechanical interactions as described by Biot's equations. A one‐dimensional exact analytical solution of the Biot's equations for the completely general solution of the transient problem in saturated, linear, elastic, porous media is presented. The problem is solved by using the Fourier series. The transient response of porous media is shown for typical material properties of a natural granular deposit and for different degrees of viscous coupling. The analytical results show the mechanics of dispersive wave propagation in saturated porous media and they should provide a useful comparison term for the existing numerical solution methods.
Hypoplastic constitutive equation with internal variables
Authors: Kolymbas D. , Herle I. , Von Wolffersdorff P. A. 
Published: August 2005

AbstractA new version of a hypoplastic constitutive equation is presented which is characterized by the introduction of a stress‐like internal parameter called back stress. The back stress is a function of the void ratio and of the hydrostatic stress. Using a unique set of material constants, the new constitutive equation describes many aspects of the behaviour of cohesionless soils including the influence of density and stress level. This is demonstrated by a series of verification tests. The determination of the material constants from laboratory tests is described analytically.
Improved computation of non‐linear advection in porous media using slightly modified basic finite element algorithms
Authors: Perrochet P. 
Published: August 2005

AbstractThe numerical stability of standard finite element schemes applied to the advection–diffusion equation is evaluated using a space‐time eigenvalue analysis. Unlike the usual approaches which only consider temporal aspects of stability, this analysis also describes the spatial stability of the solutions. To this end, the one‐dimensional advection–diffusion equation is put into an alternative semi‐discrete form which allows the derivation of a very practical stability condition. In multidimensional flow situations the latter is applied along the streamlines by means of a tensorial corrective function that prevents excessive numerical smearing of fronts or phase interfaces. The efficiency of the procedure is illustrated by an example which successfully simulates the coupling of two low miscible fluid phases in a variably saturated porous medium.
An anisotropic hardening constitutive model based on Generalized Isotropic Hardening rule for modelling clay behaviour
Authors: Lee Seung R. , Oh Seboong 
Published: August 2005

AbstractAn anisotropic hardening description is proposed on the basis of the Generalized Isotropic Hardening (GIH) rule. The key concept of the GIH rule is that any proper stress state inside or on an yield surface can be the homologic center of isotropic hardening. A concrete constitutive relationship was formulated by utilizing a simple hardening function. For verification, three sets of triaxial test results obtained from drained and undrained tests on overconsolidated clays and K0 consolidated clays were evaluated. Consequently, it was determined that the proposed model can represent any plastic deformation in reverse loading.
Kinematic hardening of soft clay in simple shear
Authors: Puzrin Alexander , Frydman Sam , Talesnick Mark 
Published: August 2005

AbstractIn a separate paper, the authors have proposed a normalized, non‐degrading form of the shear stress–shear strain relationship for undrained, cyclic simple shear of soft clay. This relationship is described in the present paper, and it is seen to include a single fatigue parameter—the mean effective stress. Application of the relationship therefore requires knowledge of the history of the mean effective stress during any loading history. The present paper proposes an effective stress path model which may be used for prediction of this history. The model is developed within the framework of bounding surface kinematic and isotropic hardening plasticity. It incorporates an isotropic hardening bounding surface, and a kinematic hardening yield surface, in which the elastic region vanishes, and so the yield surface reduces to the stress point. The normalized shear stress–shear strain relationship, developed on the basis of Iwan's model, is used to establish the shape of the cap of the bounding surface. A new translation rule is also incorporated in the model, allowing improved prediction of stress path development within the bounding surface during regular or irregular cyclic loading. Use of the proposed model to simulate the behaviour of soft clay in laboratory undrained cyclic simple shear tests shows excellent qualitative agreement, with most of the major features of the actual behaviour being predicted.
Settlement of a soil stratum subjected to an earthquake
Authors: Przewłócki JarosłAw , Knabe Włladysłlaw 
Published: August 2005

AbstractA settlement analysis of a cohesionless soil layer subjected to an earthquake is presented. A theoretical solution utilizing Bessel functions and based on the so‐called densification model for amplitudes has been obtained. This permits to calculate the settlement under cyclic loading. The simplified formula is also presented which allows for the fast and straightforward estimation of settlement.A numerical example is included giving the comparison of results obtained by different methods.
Studies on the behaviour of axially loaded tapered piles by the finite element method
Authors: Kurian Nainan P. , Srinivas Moola S. 
Published: August 2005

AbstractTapered piles represent a more equitable distribution of the pile material in several respects. In order to study their efficiency over piles of uniform section with the same material input, a three‐dimensional finite element analysis is developed. The numerical procedure accounts for the non‐linear elastic behaviour of both the soil and the pile‐soil interface. In order to include the latter, which involves relative slip and debonding, zero/non‐zero thickness interface elements are used. Three shapes of cross‐section, viz. circular, square and triangular, have been attempted for the piles. The load‐settlement behaviour under axial load predicted by the analysis is compared with laboratory test results obtained on instrumented model piles, installed as ‘replacement’ piles, and the fit obtained is found to be reasonably good. Also examined are interface shear and axial force in the pile, displacement and stress fields in the medium and the progression of failure in the latter.
A matrix for the solution of mixed rotating and non‐rotating vibration systems
Authors: Ramsden J. N. 
Published: August 2005

AbstractA method is presented based on matrix algebra for the dynamic analysis of a mixed rotating and non‐rotating vibration system. Such systems occur in practice when turbo‐alternator sets are mounted on flexible steel foundations.The mathematical model considered consists of a rotating non‐uniform, bi‐symmetric shaft connected via three or more flexible‐film bearings to a flexible structure throughout which mass is distributed. The shaft, which is assumed to rotate at constant speed, is heavy, flexible and carries several rigid axi‐symmetric discs. Viscous damping is assumed to act in all parts of the system and gravitational effects are ignored.
A theory of the solution of steady state network problems with special reference to mine ventilation networks
Authors: Yevdokimov A. G. 
Published: August 2005

AbstractWhen calculating complex interconnected systems (electrical, power, water supply, gas systems, etc.) by digital computer, a number of common problems arise, connected both with the mathematically correct formulation of the problem under investigation, and with the algorithms of the solution, the programming of which makes it possible to reduce the computing time, the store capacity and the volume of input data required. The present article is devoted to the solution of these problems. The procedure is illustrated by formulating and manipulating the equations relating to complex interconnected mine ventilation networks.