bluuebunny/crossref_metadata_2025_split huggingface dataset:
An improved accelerated initial stress procedure for elasto‐plastic finite element analysis
Authors: Thomas J. N. 
Published: August 2005

AbstractThe most flexible and generally applicable methods for elasto‐plastic analysis are those based on an incremental‐iterative form of the initial stress approach, but such methods often exhibit slow convergence. The acceleration procedure known as the alpha‐constant stiffness method is reconsidered and some modifications are proposed. The principal difference in the present approach lies in the use of a single acceleration parameter, rather than a diagonal matrix of acceleration coefficients. The new scheme shows a significant improvement in numerical stability and converges three times faster than the standard initial stress method. Some practical aspects associated with the method are discussed and a number of applications are presented.
Stresses and displacements in an elastic mass due to distributed loading by discretization technique
Authors: Sharma K. G. , Rao G.‐Venkatappa 
Published: August 2005

AbstractNumerical solutions have been obtained for stresses and displacements in a linear elastic half space due to distributed loads of circular, rectangular and elliptical shapes. The technique primarily involves use of a multi‐dimensional numerical integration technique to integrate point load solutions over the distributed loading after discretizing the area into a finite number of elements. Both uniform vertical and shear loads have been considered as well as vertical conical loads and inward shear loads. The technique evolved facilitates the determination of stresses and displacements by the use of mini‐computers and is neither as tedious and cumbersome as the use of tables and charts nor as costly as FEM solutions.A detailed comparison has been presented between the results obtained by the numerical solutions and those of the existing analytical solutions wherever they are available. It is found that the agreement between the two is within one per cent for displacements at all depths for the different cases studied. The matching is also good in the case of stresses, except at shallow depths.
The analysis of deformations caused by loading applied to the walls of a circular tunnel
Authors: Booker J. R. , Carter J. P. 
Published: August 2005

AbstractAn analytical solution to the problem of a load applied to a portion of the wall of a circular tunnel installed deep in a homogeneous isotropic material has been found. The solution is obtained by taking a Fourier transform, in the axial direction, of the field quantities and then representing these as a Fourier series in the polar angle. The integration which is necessary for the inversion of Fourier transforms has to be performed numerically using Gaussian quadrature.The solution has been used to analyse the problem of uniform normal loading applied over rectangular patches of the tunnel wall. An indication of how the solution can be applied to the tunnel jacking problem is given.
A computer method for stability analysis of caverns in jointed rock
Authors: Belytschko Ted , Plesha Michael , Dowding Charles H. 
Published: August 2005

AbstractA simple rigid block model has been developed for analysing the stability of caverns and tunnels in jointed rock. Rigid block interactions are idealized as linear edge‐to‐edge contacts with a zero joint tension constraint and a Mohr‐Coulomb friction law. In the method, the minimum friction angle for stability is determined by sequentially eliminating tension and then minimizing the shear. It is demonstrated through examples that the minimum joint friction angle which results in a stable configuration is independent of the stiffness of the joint, and depends only upon the loading and geometry of the jointing and cavern. This insensitivity of stability to the normal and tangential joint stiffnesses, which can be difficult to obtain, is very useful for design purposes.
A differential slice approach to the problem of retaining wall loading
Authors: Michalowski Radoslaw L. 
Published: August 2005

AbstractA differential slice technique is applied in order to obtain the solution for the pressure distribution on rigid retaining walls. The technique is based on a statical analysis of a plane differential slice, for which only the global equilibrium is required. An analytical solution to the problem is found for a non‐cohesive material and a linear slip surface. For more complicated cases the numerical solution is required.
F. E. analysis of field consolidation curves obtained with the modified borehole shear device (BHSD)
Authors: Demartinecourt Jean Pierre , Bauer Gunther E. , Soulié Michel 
Published: August 2005

AbstractA modified version of the bore hole sheat device (BHSD) was used to obtain field consolidation curves in a soft sensitive clay. The Porewater pressure dissipation was monitored at the centre of one of the shear plates.This paper describes briefly the in situ device employed and demonstrates the basic features of the linearelastic F. E. program ‘SOL’. A detailed study is made to simulate the field behaviour with the finite element approach. Comparisons are made between the field and analytical consolidation behaviour. Difficulties in predicting the value of the coefficient of consolidation of a sensitive clay using the BHSD consolidation curves are discussed.
Visco‐damage tension model for rocks in ground‐shock applications
Authors: Whitman Lorraine 
Published: August 2005

AbstractA simple rate‐dependent tension model, tailored primarily for rocks in ground‐shock calculations, has been constructed. It is formulated as an internal state variable theory with spherical void development taken to approximate the underlying dissipative micromechanism. This simplifying assumption of ductile, rather than brittle, damage growth has been made to enhance the practicality of the model for large‐scale problems. The model has been restated within the fromework of (strain‐softening) viscoplastcity to associate it with the desirable mathematical properties of the latter theory. The tension option, extended to include healing in the post‐damage compressive phase, has been implemented in a standard cap constitutive routine and is referred to as the visco‐damage tension model. Model parameters are selected for a shale‐like material. Results of uniaxial shock‐loading strain‐rate calculations exhibit desired characteristics in tension. Damage‐related hysteretic effects are illustrated through cyclic loading calculations. It is planned to develop more effecient computational procedures to facilitate adoption of the model into large‐scale ground shock calculations. Anisotropic extensions of the model will then be considered.
Stability and bifurcation of undrained, plane rectilinear deformations on water‐saturated granular soils
Authors: Vardoulakis I. 
Published: August 2005

AbstractStability and bifurcation of plane‐strain, undrained, rectilinear deformations on water‐saturated granular soil specimens are discussed. The soil, sand or normally consolidated clay, is described by a 2D‐flow theory of plasticity for frictional material with non‐associated flow rule. Contractant material become unstable (liquefies) at the state of maximum deviatoric stress. For dilatant material the dominant failure mode is shear banding that occurs close to the state of maximum principal effectivestress ratio. The theoretical findings are supported by and are used to explain existing experimental results.
Simple model for transient soil loading in earthquake analysis. II. Non‐associative models for sands
Authors: Pastor M. , Zienkiewicz O. C. , Leung K. H. 
Published: August 2005

AbstractThis paper extends the bounding surface, generalized plasticity, model of Part I to reproduce the behaviour of sands under both static and transient loading.The essential features of the first model are preserved but the following changes are introduced:

The shape of the yield surface is modified.
A non‐associative flow rule is introduced.
The hardening parameter of the bounding surface includes not only volumetric but also deviatoric plastic strain.
Plastic volumetric and deviatoric strains are introduced during unloading.
Each of these modifications can be introduced separately in a hierarchical manner to model in an improved way the behaviour of sands. Good comparison with experimental observations is recorded. The simplicity of the original model is preserved with modifications being introduced progressively to model rising complexity of the phenomena.
Response of porous beds subjected to random waves
Authors: Layas F. M. , Rahman M. S. 
Published: August 2005

AbstractA general analysis procedure is developed for the evaluation of the effective stress response of a porous ocean bed subjected to random waves. The ocean floor soil is treated as a saturated porous elastic medium and Biot's theory is used to formulate the coupled flow and deformation. The waves are treated as a random process which is described by Pierson–Moskowitz spectrum. The derived statistical properties of the response are used to evaluate the probability of failure in ocean bed.
Mixed time integration for the transient analysis of jointed media
Authors: Plesha Michael E. 
Published: August 2005

AbstractA constitutive operator split method with implicit‐explicit time integration is presented for the transient analysis of rigid block models of jointed media. The linear portion of the joint constitutive law is integrated by an implicit method and the non‐linear, time dependent portion is integrated by an explicit method. The method features the stability of implicit procedures as well as the flexibility of explicit procedures for non‐linear problems. The solutions obtained with this method are compared to the solutions obtained by the explicit central difference method; in all cases there is good to excellent agreement. For some problems, particularly for those with low frequency excitation, it is shown that the implicit‐explicit method can result in a substantial savings over more conventional explicit methods.
Analysis of excavations in jointed rock of infinite extent
Authors: Sofianos A. I. , Watson J. O. 
Published: August 2005

AbstractThe subject of this work is the development of a code to study the behaviour of stratified and jointed rock masses around underground excavations. The rock mass is divided into two types of regions, one which is supposed to exhibit linear elastic behaviour and which may extend to infinity, and the other which will include discontinuities that behave inelastically. The former has been simulated by a symmetric direct, boundary integral, plane strain, quadratic, orthotropic module, and the latter by quadratic plane strain, membrane and inelastic joint elements. The two modules are coupled in one program. Sequences of loading include static point, pressure, body and residual loads, construction and excavation sequences, and quasi‐static earthquake load. The programe is interactive, with graphics. A numerical example is presented to illustrate the method.
An integral method for predicting hydraulic fracture propagation driven by gases or liquids
Authors: Nilson R. H. 
Published: August 2005

AbstractHydraulic fracture propagation is predicted by a general numerical procedure which satisfies the transport equations in a global or integral sense over the entire fracture and over a small control volume near the leading edge. At each discrete time step the pressure distribution is selected from a four‐parameter family of profiles such that the stress intensity is equal to the critical value at the tip of the fracture and the integral equations are satisfied. Comparisons with previous analytical and, numerical solutions indicate accuracy within 10 per cent for a variety of test problems include wedge‐shaped and envelope‐shaped fractures, laminar and turbulent flows, incompressible liquids and ideal gases, permeable and impermeable media, prescribed inlet pressure and prescribed flow rates. CPU time is typically a few seconds for a tenfold increase in fracture length. The method has been applied to explosively driven and propellant‐driven gas fracturing problems as well as the traditional pump‐driven hydraulic fracturing problem.
Stability analysis of an advanced vault excavation with unlined invert according to the finite element method
Authors: Wittke W. , Feiser J. , Krieger J. 
Published: August 2005

AbstractThis paper attempts to present questions associated with the stability of advanced vault excavations which are driven according to the New Austrian Tunnelling Method (NATM) without lining of the temporary invert. The dimensions of the investigated cross‐section correspond to those of the tunnels driven on the new high‐speed tracks for the German Federal Railways. Two possible modes of failure are investigated with the aid of continuum mechanics analyses according to the finite element method. Reference is made to structural measures which may positively influence the stability of this construction stage. Furthermore, the manner in which the stress‐strain behaviour of a horizontal alternating sequence with open vertical discontinuities may be taken into consideration in a continuum mechanics analysis is also demonstrated. The analysis results presented clearly show that the load‐carrying action of the rock mass which characterizes the NATM may be better described by rock mechanics analyses according to the finite element method than by conventional procedures.
The behaviour of an impermeable flexible raft on a deep layer of consolidating soil
Authors: Booker J. R. , Small J. C. 
Published: August 2005

AbstractAnalytic solutions to the problem of the time‐settlement behaviour of raft foundations have been limited in the past to flexible or rigid loadings, and have treated the foundation as being completely permeable. In this paper, solutions are presented for smooth circular rafts of any flexibility causing consolidation of a deep homogeneous clay layer, where the raft may be considered permeable or impermeable.Results for the time‐dependent behaviour of contact stresses, pore pressures, raft displacements and moment in the raft are presented.
A boundary integral equation technique for visco‐elastic stress analysis
Authors: Carini Angelo , Gioda Giancarlo 
Published: August 2005

AbstractOn the basis of the correspondence principle of visco‐elasticity, an application is discussed of the boundary integral equation method to the solution of time‐dependent stress analysis problems. The adopted solution technique, in addition to the time‐dependent stress and strain distributions, enables the determination of a measure of the error affecting the numerical results. The governing equations for the plane strain visco‐elastic problem are derived with reference to a generalized Kelvin model consisting of the series of any number of simple kelvin elements, having both volumetric and deviatoric components. To get some insight into the overall performance of the technique, the results obtained in the solution of some test examples are discussed and compared with those dering from the available closed from solutions.
Adaptive methods to solve free boundary problems of flow through porous media
Authors: Chung Kyoon Yang , Kikuchi Noboru 
Published: August 2005

AbstractGrid adaptive methods combined with domain adaptation are discussed for two‐dimensional seepage flow problems with free boundaries through porous media. Examples of grid and domain adaptive methods are presented to demonstrate several ways to predict grids and shapes of free boundaries using an iterative scheme. Finally, the combined adaptive methods are applied to obtain smooth non‐oscillatory shape of a free boundary of seepage flow through non‐homogeneous porous media.
Elastic consolidation around a point sink embedded in a half‐space with anisotropic permeability
Authors: Booker J. R. , Carter J. P. 
Published: August 2005

AbstractThe complete solution is presented for the transient effects of pumping fluid from a point sink embedded in a saturated, porous elastic half‐space. It is assumed that the medium is homogeneous and isotropic with respect to its elastic properties and homogeneous but anisotropic with respect to the flow of pore fluid. The soil skeleton is modelled as a linear elastic material obeying Hooke's law, while the pore fluid is assumed to be incompressible with its flow governed by Darcy's law. The solution has been evaluated for a particular value of Poisson's ratio of the solid skeleton, i.e. 0.25, and the results have been presented graphically in the form of isochrones of excess pore pressure and surface profile for the half‐space. The solutions presented may have application in practical problems such as dewatering operations in compressible soil and rock masses.
Numerical Laplace–Fourier transform inversion technique for layered soil consolidation problems; II, Gibson soil layer
Authors: Harnpattanapanich T. , Vardoulakis I. 
Published: August 2005

AbstractThe numerical Laplace–Fourier transformation technique previously presented by the authors11 is used here for solving the consolidation problem of a finite inhomogeneous soil layer whose shear modulus is increasing linearly with depth. Parametric studies are performed and the results are critically discussed.
One‐dimensional advective–dispersive transport into a deep layer having a variable surface concentration
Authors: Booker J. R. , Rowe R. K. 
Published: August 2005

AbstractTwo analytic closed form solutions for the one‐dimensional advection–dispersion equation are presented. These solutions take account of changes in surface concentration with time as mass is transported into the soil. The first solution is developed for the case of rapid landfill construction. The second solution considers a time‐dependent mass input to the landfill. The use of these solutions is illustrated by a number of examples and it is shown that consideration of the finite mass of contaminant within the landfill can significantly affect the concentration profiles beneath the landfill.
Computation of gas pressure profiles relevant to outbursting in coal mines
Authors: Schlanger Harry P. , Paterson Lincoln 
Published: August 2005

AbstractHigh gas pressure gradients in coal seams play an important role in the occurrence of outbursts during underground coal mining. Excess stress resulting from body forces due to high pressure gradients contributes to the structural failure of coal. We present a one‐dimensional model of a dry, rigid coal seam with a moving mine face and determine gas pressures by solving the nonlinear equation for gas flow in a porous medium. An implicit finite difference scheme is used. Since the structure of coal has a dual porosity nature, we consider flow through both the macropores and the micropores. We investigate the effect of changes in mining velocity, idle mining periods and coal properties on the pressure profile in the coal seam. When the yield zone behind the moving mine face is taken into account, the greatest body force occurs on the least competent section of the coal seam.
Plastic collapse of long piles under inclined loading
Authors: Murff J. D. 
Published: August 2005

AbstractA method is detailed for the plastic collapse analysis of long piles typical of offshore foundations, subjected to inclined loading. The method is based on the upper bound method of plasticity. It easily incorporates both axial and lateral variable soil resistance and variable pile cross section properties. The incorporation of plastic yield interaction between axial load and moment for the pile is a key feature of the method. The solution can itself be cast in the form of a curve representing axial and lateral load interaction and is amenable to incorporation in the analysis of foundation systems such as pile groups.
Gravity‐induced stresses near axisymmetric topography of small slope
Authors: McTigue D. F. , Mei C. C. 
Published: August 2005

AbstractAn approximate, analytical solution is found for the gravity‐induced stresses in the neighbourhood of an axisymmetric topographic feature on an elastic half‐space. The solution is in the form of a perturbation expansion in powers of the characteristic slope, ϵ. The leading order problem, at O(1), is for a distributed normal load on a plane half‐space. The O(ϵ) correction is due to a distributed shear traction. The vertical variation of the near‐surface stress perturbation and the rotation of the principal stress directions are O(ϵ) effects, and thus include contribution s of like order from both the normal and shear loads. The method requires general solutions for axisymmetric, normal and shear tractions of arbitrary radial distribution, and these are found in terms of Hankel transforms.
Elasto‐plastic analysis of an underground opening by FEM and coupled FEBEM
Authors: Varadarajan A. , Sharma K. G. , Singh R. B. 
Published: August 2005

AbstractThe elasto‐plastic analysis of a circular underground opening using the finite element method (FEM), the coupled finite element and the boundary element method (FEBEM) is presented. The coupling procedure and elasto‐plastic formulation are discussed. The effect of in situ stress ratio on yielded zone, displaced shape and principal stresses is presented. The results of FEBEM analysis are compared with those obtained from FEM. The computation time and the number of iterations as required by FEBEM and FEM are compared.
Reservoir induced seismicity—a new model
Authors: Saxena S. K. , Ger A. Metin , Sengupta A. 
Published: August 2005

AbstractDeficiencies of different existing models on ‘Reservoir Induced Seismicity’ have been discussed and a new mathematical model, which enhances a better understanding of triggering mechanism in terms of changes in effective stresses, in situ stresses and water level variations, has been discussed in this paper. In the model fractured rock is simulated by a fluid‐filled elastic material subject to Mohr–Coulomb failure criterion. The model has been found to be capable of responding effectively to site specific attributes. It can recognize and explain the phenomenon of time lag observed in several actual cases. It is also capable of simulating stabilization of rock–reservoir system after a period of activities that follow the initial stage of filling. One dimensional and two dimensional, isotropic and anisotropic cases have been analysed and the model predictions have been found to agree qualitatively with the field observations.
An identification technique for evaluation of phenomenological coefficients in coupled flow in unsaturated soils
Authors: Yong Raymond N. , Xu Da‐Ming 
Published: August 2005

AbstractTo determine moisture movement and heat transfer through an unsaturated soil under temperature and volumetric water content gradients, it is necessary to have knowledge of phenomenological coefficients of the soil. However, in unsaturated flow, i.e. flow through unsaturated soil, these phenomenological coefficients are not constants, but vary with volumetric water content as well as temperature. In this paper, an identification technique is proposed for evaluation of the phenomenological coefficients. The phenomeno‐logical coefficients are first assumed to be certain kinds of functions of volumetric water content and temperature. The choice of the functional forms is based on an understanding of the physical situation, and previous knowledge of water flow in the isothermal case. The constant parameters associated with the functional forms are evaluated through the use of the identification technique. Once these phenomenological coefficients are obtained as certain functions of the volumetric water content and the temperature for a specified soil, analysis of coupled moisture flow and heat transfer in the unsaturated soil can proceed.