bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of leaky sheetpile by Summary Representation
Authors: Karadi Gabor M. , De Miguel Enrique , Krizek Raymond J. 
Published: August 2005

AbstractA numerical technique called Summary Representation was used to solve the problem of seepage through a leaky sheetpile; this particular method was selected owing to its accuracy and computational speed. Seepage parameters were evaluated quantitatively and the influence of the leakiness of sheetpiles in a porous medium underlain by an impervious horizontal stratum was determined. The case of a single sheetpile was first considered, and the effect of the depth of penetration and coefficient of leakiness on the total rate of flow and on the values of the exit gradient was analysed. Next, the flow under an impervious dam was considered to assess the accuracy of the method. Finally, the case of seepage under a dam with leaky sheetpiles at both ends was studied, including the effect of the leaky sheetpiles on the uplift pressure acting along the foundation of the dam. Patterns of seepage through the flow line deformation that is caused by the leakiness of the sheetpiles.
Determination of the critical slip surface in slope stability computations
Authors: Baker R. 
Published: August 2005

AbstractThe analysis of the stability of slopes using limiting equilibrium considerations necessitates the determination of the critical slip surface which yields the minimal factor of safety. The numerous methods currently available for slope stability analysis provide a procedure for assigning a factor of safety to a given slip surface, but do not consider the problem of identifying the critical conditions.This paper presents an effective minimization procedure based on dynamic programming by which the minimal factor of safety, and the corresponding surface, are determined simultaneously. This procedure SSDP (Slope Stability by Dynamic Programming), couples the minimization scheme with Spencer's method of slope stability analysis. It may be applied to slopes of any geometry, layering, pore pressure and external load distributions. No arbitrary restrictions are placed on the shape of the slip surfaces, and the analysis satisfies all equilibrium equations.Application of the procedure to slope stability problems reported in the literature shows that for a given slip surface the procedure yields factors of safety which are almost identical to those reported, but in every case a more critical slip surface, with a lower factor of safety, may be found.
A statistical study of fabric in a random assembly of spherical granules
Authors: Oda M. , Nemat‐Nasser S. , Mehrabadi M. M. 
Published: August 2005

AbstractIt is commonly accepted that the mechanical behaviour of granular masses is strongly affected by their microstructure, namely the relative arrangement of voids and particles, i.e. the granular fabric. Therefore, parameters which characterize the granular fabric are of paramount importance in a fundamental description of the overall macroscopic stresses and deformation measures. In this paper several measures of granular fabric are introduced for a random assembly of spherical granules, using a statistical approach. In particular, a second‐order symmetric tensor, Fij, emerges from this consideration, which seems to be of fundamental importance for the description of fabric, and which is closely related to the distribution of the contact normals in the assembly. The relation between fabric measures presented here and those discussed by other investigators is also discussed.
Vibration of a rigid disc on a transversely isotropic elastic half space
Authors: Kirkner David J. 
Published: August 2005

AbstractThe problem of a massless, rigid disc vibrating harmonically on a ‘constrained’ transversely isotropic elastic half space is considered. The material is called constrained because it is assumed that the elastic constants satisfy a certain equation. The problem for each mode of vibration is reduced to the solution of a Fredholm integral equation of the second kind. Results are presented to show the general effect of the material anisotropy.
Incrementalization procedure for elasto‐plastic constitutive model with multiple, intersecting yield surfaces
Authors: Lade Poul V. , Nelson Richard B. 
Published: August 2005

AbstractConstitutive models for description of the non‐linear stress‐strain behaviour of engineering materials are often developed and presented in forms which cannot be employed directly in non‐linear matrix computer analysis codes. Presented herein is a procedure for developing the incremental stiffness matrix for an elasto‐plastic material model with multiple, intersecting yield surfaces. Associated or non‐associated flow may occur on the individual yield surfaces. The material stiffness matrix is non‐symmetric if non‐associated flow occurs on any one of the yield surfaces. In order to illustrate the matrix forms which are generated, the case of a recently developed model with two yield surfaces is presented in detail. This model involves associated flow on one and non‐associated flow on the other yield surface.
On the dynamic stiffness of circular ring footings on an elastic stratum
Authors: Tassoulas John L. , Kausel Eduardo 
Published: August 2005

AbstractCircular ring footings on an elastic stratum are considered. The static and dynamic stiffnesses are calculated using an efficient numerical technique. The results indicate that the static torsional and rocking stiffnesses of a ring footing do not deviate significantly from the corresponding stiffness of the circular footing for values of the inner‐radius‐to‐outer‐radius ratio up to about 0.75. The static horizontal and vertical stiffnesses change considerably only for values of this ratio greater than about 0.60. The change in the stiffness and damping coefficients is small for values of the ratio between 0 and 0.5.
Numerical simulation of unsteady fluid flow and propagation of a circular hydraulic fracture
Authors: Cleary M. P. , Wong S. K. 
Published: August 2005

AbstractA computational procedure is developed for solving the problem of a circular hydraulic fracture propagating under the action of frac‐0fluid being pumped in at a central wellbore. The crack is modelled as continuous distributions of ring dislocations and the resulting elasticity singular integral equation is solved numerically. The fluid flow equations are approximated by local and global interpolation finite difference schemes. The coupling between elasticity and fluid flow is handled numerically, by, two different algorithms: one iterates on crack tip velocity whereas the other varies the time step size until it agrees with the chosen increment in crack length. Sample results are given; it is found that the velocity algorithm is computationally more, efficient and more stable. The model allows detailed tracing of pressure distribution and fluid flow in the fracture, even under complex conditions of cyclic injection and fluid rheology. It may serve as a stand‐alone model of (horizontal) hydrafracs–especially at shallow depths–or it may be used as a reference frame to test the various numerical formulation/algorithms required for the ongoing development of a fully 3‐D hydrafrac simulator.
Theoretical study on the stability of a reservoir created by the intersection of a fluid‐filled crack with an oblique joint for the extraction of geothermal heat
Authors: Abé H. , Hayashi K. , Arima S. 
Published: August 2005

AbstractOn the basis of the two‐dimensional theory of elasticity, the theoretical analysis of a vertical, fluid‐filled crack intersecting and oblique joint has been made for the extraction of geothermal heat from hot, dry rock masses, where the opening of the joint near a point of intersection and the frictional resistance against slips along the joint are taken into account. The stress intensity factors are evaluated for discussing crack kinking at the upper joint tip, and the sufficient conditions on theinclination of the joint and on the length between the upper joint tip and the point of intersection are obtained for keeping a fluid‐filled crack stable just beneath a joint. It is also shown that the volume of the stable reservoir created by using a joint is much larger than that of a fluidfilled crack in a jointless rock mass, even if the joint is oblique and is opened up by the fluid pressure.
Variational principles and finite element simulations for thermo‐elastic consolidation
Authors: Aboustit B. L. , Advani S. H. , Lee J. K. 
Published: August 2005

AbstractIn this paper, a general variational principle for the initial boundary value problem of quasi‐static thermoelastic consolidation is developed by assuming infinitesimal deformation and an incompressible fluid flowing through a linearly elastic solid. By manipulating the coupling operators, an extended form of the variational pronciple is derved. The associated finite element formulation based on this principle is presented and numerical applications for plane strain thermo‐elastic consolidation are revealed.
A large strain theory for the two dimensional problems in geomechanics
Authors: Kiousis Panagiotis D. , Voyiadjis George Z. , Tumay Mehmet T. 
Published: August 2005

AbstractAn incremental finite element formulation for elasto‐plastic bodies subjected to large strains and large displacements is presented in this paper. The formulation is in Lagrangian co‐ordinates (material description) and the plasticity model employed is the extended von Mises. The bearing capacity of a strip footing and the stability of an earth slope illustrate the applicability of this theory.
Vibration of a rigid footing—a finite model for the elastic half space
Authors: Damisa O. 
Published: August 2005

AbstractA problem common to most numerical methods of analysing the vibration of a rigid body on an elastic half space is indentified especially as regards the arbitrary truncation of the semi‐infinite half space or the numerically expensive computations involved in some of the methods. This paper presents a boundary integral equation (BIE) method of defining a finite domain to replace the half space and consists of evaluating the BIE over the domain. A mathematical justification is provided for defining the domain, and the error involved in such truncation of the half space in shown to be small. Yet the computations are very cheap owing to the simple trigonometric/algebraic functions involved in the BIE. The accuracy of the method is quite commendable especially as seen from the results presented for the circular foundation for which analytical and experimental solutions are available for comparison.
Analysis of a point sink embedded in a porous elastic half space
Authors: Booker J. R. , Carter J. P. 
Published: August 2005

AbstractClosed‐form solutions are presented for the steady‐state distributions of displacement, pore pressure and stress around a point sink embedded in a homogeneous, isotropic elastic half space. These solutions have been evaluated for a typical case of a sink (pump) buried in sand and the magnitude of the settlement of the ground surface has been estimated.
Finite element analysis of mechanisms of pile group behaviour
Authors: Pressley J. S. , Poulos H. G. 
Published: August 2005

AbstractSolutions are presented for the non‐linear load‐settlement behaviour of square‐configuration pile groups. The groups are represented by an equivalent axially symmetric model, and a non‐linear finite element is used to examine the mechanisms of group behaviour and their variation with pile spacing. It is shown that, at close spacings, the block failure mechanism occurs, with significant plastic zones being developed below the group and full pile‐soil slip only being developed along the outer piles. As the pile spacing increases, the failure mechanism gradually changes to the ‘single‐pile’ mode, whereby full pile‐soil slip occurs along all piles. Within the limitations of accuracy of the finite element solution, the values of group settlement ratio and efficiency are in reasonable agreement with values derived from existing theories.
A hierarchical approach for constitutive modelling of geologic materials
Authors: Desai C. S. , Somasundaram S. , Frantziskonis G. 
Published: August 2005

AbstractA hierarchical concept is proposed for the development of constitutive models to account for various factors that influence behaviour of (geologic) materials. It permits evolution of models of progressively higher grades from the basic model representing isotropic hardening with associative behaviour. Factors such as non‐associativeness and induced anisotropy due to friction and cyclic loading, and softening are introduced as corrections or perturbations to the basic model. The influence of these factors is captured through non‐associativeness manifested by deviation from normality of the plastic strain increments to the yield surface, F. Details of four models: isotropic hardening with associative behaviour, isotropic hardening with non‐associative behavioural anisotropic hardening and strain‐softening with a damage variable are presented. They are verified with respect to laboratory multiaxial test data under various paths of loading, unloading and reloading for typical soils, rock and concrete. The proposed concept is general, yet sufficiently simplified in terms of physical understanding, number of constants and their physical meanings, determination of the constants and implementation.
Influence of a wall system on the interaction between soil and foundation plates
Authors: Kujawski J. , Wiberg N.‐E. 
Published: August 2005

AbstractThe paper considers the influence of a building wall system on the interaction between the soil and the foundation plate. A simplified semi‐analytical finite element method gives an economical solution for large three‐dimensional soil‐structure interaction problems. The simplified method appears to be sufficiently accurate for engineering purposes.Numerical results presented show significant influence of building walls on the foundation‐plate‐soil interaction.
Comparison of transmitting boundaries in dynamic finite element analyses using explicit time integration
Authors: Simons H. A. , Randolph M. F. 
Published: August 2005

AbstractExplicit time integration schemes provide an efficient solution to non‐linear dynamic finite element analyses of geotechnical problems especially when high frequency response is important. Such explicit time integration schemes require one of two distinct transmitting boundary formulations to overcome the problem of radiation damping. These are the superposition boundary approach, which involves the cancellation of the reflected waves by combining the solutions of two different boundary conditions and the viscous boundary approach, which involves the absorption of incident wave energy by frequency independent viscous dashpots. The theoretical justification of these two approaches and their means of implementation are reviewed. The solutions obtained using the two different boundary approaches to the problem of a rigid massless circular footing vibrating on an elastic half‐space are compared with an independent theoretical solution. The performance of the boundaries for problems involving step loading is also examined and the implications for any loading pattern with a non‐zero time average are discussed.
Response of poroelastic halfspace to steady‐state harmonic surface tractions
Authors: Halpern Marc R. , Christiano Paul 
Published: August 2005

AbstractTraditionally, most formulations of dynamic halfspace problems have represented the material as either an elastic or a viscoelastic solid. Herein the counterpart of Lamb's elastodynamic problem is reformulated and solved for a liquid‐saturated poroelastic halfspace using Biot's theory of poroelasticity. The responses of the solid and fluid phases are evaluated due to steady‐state harmonic concentrated loads applied to each phase at the surface. The solutions are presented over a broad range of permeabilities and are compared to solutions to Lamb's problem for equivalent drained and undrained solids. Methodology is then introduced by which these results are treated as Green functions for the solution of a mixed boundary‐value problem. namely, the response of the poroelastic halfspace to steady‐state harmonic vertical motion of a rigid. massless plate. It is observed that small differences exist among overall compliance functions for a drained solid, an undrained solid, and a liquid‐saturated porous, halfspace. However, use of the poroelastic model permits the distribution between effective skeletal normal stresses and fluid stresses to be determined.
Generalized displacements of a rigid elliptical anchor embedded at a bi‐material geological interface
Authors: Selvadurai A. P. S. , Au M. C. 
Published: August 2005

AbstractThe present paper examines the class of problems related to a flat rigid anchoring region which is embedded at a geological interface. The analysis focuses on the evaluation of the elastic stiffness of the embedded anchor. A boundary element technique is used estimate the axial, rotational and translational stiffnesses of the anchor. These estimates are compared with a set of bounds which are evaluated in exact closed form. These bounds are obtained by invoking kinematic and/or traction constraintsat the geological interface. The numerical results presented in the paper illstrate the manner in which the various stiffnesses of the anchoring region are influenced by the elastic properties of the surrounding geological media.
Effective stress analysis of seismic site response
Authors: Prevost Jean H. 
Published: August 2005

AbstractA procedure is presented which allows site response analyses to be performed with any general multidimensional finite element analysis package. Numerical results which corrorate the theory are presented. Also, as an illustration of the procedure, results of an effective stress analysis for the scismic response and liquefaction of a horizontally layered saturated sand deposit are presented.
Vertical deformation of rigid foundations of arbitrary shape on layered soil media
Authors: Chow Y. K. 
Published: August 2005

AbstractA numerical procedure is described for the analysis of vertical deformation of smooth, rigid foundations of arbitrary shape on homogeneous and layered soil media. The contact area at the interface of the foundation and soil medium is approximated by square subdivisions. The response of the system is then obtained from the superposition of the influence of the individual subdivisions. The flexibility influence coefficients are based on equivalent smooth, rigid circular areas with the same contact area as the square subdivisions. For foundations on a homogeneous, isotropic elastic half‐space, the flexibility coefficients are given analytically by the integrated forms of the Boussinesq's solution. For a layered soil medium, the flexibility coefficients are determined from an axisymmetric finite element analysis which is essentially two dimensional. Thus, there is no necessity for a full three‐dimensional finite element analysis. Comparison with solutions obtained using the integral transform technique for smooth, rigid rectangular foundations on a homogeneous, isotropic elastic half‐space shows good agreement. Parametric solutions are presented for the response of rectangular foundations on some ‘typical’ soil profiles. The use of a simplified method to estimate the settlement of rectangular foundations on a layered soil medium by superposing solutions for homogeneous, elastic strata is discussed.
Stability analysis of slopes with general nonlinear failure criterion
Authors: Zhang X. J. , Chen W. F. 
Published: August 2005

AbstractThe upper bound method of limit analysis of perfect plasticity is applied to stability problems of slopes with a general nonlinear failure criterion. Based on the upper bound method, a numerical procedure is suggested, which converts the complex system of differential equations to an initial value problem. Using this numerical procedure, an effective numerical method, called the inverse method, suitable for the solution of slope stability problems in soil mechanics with a general nonlinear failure criterion, is presented. A general nonlinear failure criterion for soils is also suggested, from which the effects of nonlinear failure parameters on the stability of slopes are discussed.
Circular plates on Pasternak elastic foundations
Authors: Dumir P. C. 
Published: August 2005

AbstractThis study deals with the geometrically nonlinear axisymmetric static and transient response of cylindrically orthotropic thin circular plates resting on Pasternak elastic foundations subjected to uniformly distributed loads. Clamped and simply‐supported plates with radially movable and immovable edges have been considered. The von‐Kármán type nonlinear governing equations have been solved using orthogonal point collocation method in the space domain and Newmark‐β scheme in the time domain. The maximum transient response to step loads has also been predicted from static response. The influence of the foundation parameters on the response has been investigated.
A stochastic approach in modelling and estimating geotechnical data
Authors: Christakos George 
Published: August 2005

AbstractA rational approach for dealing with uncertainties in geotechnical performance predictions is presented. First, sources of uncertainty are identified and treated stochastically. Then, the relative importance of each source is analysed and its influence in the decision‐making process is evaluated. Strong inferences concerning the spatial structure of soils are drawn from field or laboratory measurements, while maintaining consistency with engineering knowledge and experimenal findings. Optimal estimates of soil properties are derived by a stochastic method which is mathematically meaningful and portrays adequately the real behaviour of the data. The method is powerful when the data exhibit homogeneous or non‐homogeneous characteristics, and works well with any kind of data support. Its applicability is illustrated in a case study involving field vane data. Furthermore, contributions and benefits of the results obtained to the geotechnical decisions and design are discussed.
Rheological analysis of tunnel excavations by means of coupled finite element (FEM)–boundary element (BEM) analysis
Authors: Swoboda G. , Mertz W. , Beer G. 
Published: August 2005

AbstractTo facilitate the practical numerical analysis of tunnel structures by means of the finite element method in the case of viscoplastic properties of the rock mass and viscoelastic properties of the shotcrete, this method is coupled to boundary elements. In this way, the unchanged properties of the boundary element region provide enormous savings in computing time. In order to improve the numerical stability of such calculations, a variable time‐step analysis was employed for each time step with an iterative correction method. Characteristic values are obtained from measured values by back‐analysis.
Heat extraction through a geothermal reservoir on an oblique fault plane
Authors: Shibuya Y. , Sekine H. , Takahashi Y. 
Published: August 2005

AbstractThe heat extraction through a geothermal reservoir on an oblique fault plane in the earth's crust is considered. The fault could be modelled mechanically as a frictional contact interface of two elastic bodies. The heat is recovered by circulating fluid through the reservoir, and then the surface of the reservoir is cooled by the fluid. The analysis is based on the two‐dimensional theory of quasi‐static thermoelasticity. It is concluded from numerical calculations that a geothermal reservoir can be created on an oblique fault plane, and the opened region, i.e. the fluid‐filled region, increases gradually with time during the heat extraction. Also discussed are the effects of the fluid pressure and the coefficient of friction on the behaviour of the reservoir.