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    Wyświetlanie 1-8 z 8
    Tytuł:
    Evaluation of liquefaction potential for loose minefill slopes
    Autorzy:
    Kudella, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1954561.pdf
    Data publikacji:
    2022-02-07
    Wydawca:
    Politechnika Gdańska
    Tematy:
    liquefaction
    granular materials
    hypoplasticity
    instability
    failure
    Opis:
    Uncompacted embankments of certain fine sands exhibit a spontaneous liquefaction potential, which cannot be evaluated basing on undrained shear strength alone. A novel procedure for stability analysis has been developed, basing on Hill's stability criterion and a hypoplastic constitutive law. With given relative densities, assumed initial stress states and variations of perturbation directions, stability or instability of slope sections can be assessed. Catastrophic landslides observed in the past could thus be explained.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2000, 4, 3; 439-451
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Introduction to hypoplasticity (GeoMath1)
    Autorzy:
    Kolymbas, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/1954567.pdf
    Data publikacji:
    2000
    Wydawca:
    Politechnika Gdańska
    Tematy:
    granular materials
    yield
    hysteresis
    dilatancy
    constitutive equation
    Opis:
    Rational mechanics offers a tool to objectively describe the mechanical behaviour of granular materials by means of non-linear tensorial functions. This new framework is called hypoplasticity and is characterized by the simplicity of the mathematical formulations. The stress dependency of incremental stiffness, yield, loading-unloading hysteresis and dilatancy-contractancy are included. One of the features of hypoplasticity is that yield is a natural outcome of the theory and needs not be calibrated a priori. Also loss of uniqueness and localization of deformation are realistically predicted by hypoplasticity.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2000, 4, 3; 343-366
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    FE-modelling of behaviour of granular anchors in rock and soils
    Autorzy:
    Wehr, J.
    Tejchman, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1954551.pdf
    Data publikacji:
    2000
    Wydawca:
    Politechnika Gdańska
    Tematy:
    anchor
    finite element method
    granular materials
    hypoplasticity
    polar continuum
    Opis:
    The paper is concerned with granular anchors in rock and soils. Model tests and numerical calculations were performed. The effect of different parameters on the behaviour of anchors was investigated: anchor length, anchor diameter, initial density and mean grain diameter of the granular material, anchor roughness and stiffness of the borehole wall. The experiments were modelled with a finite element method and a polar hypoplastic constitutive relation. The relation can capture the salient properties of granular materials during shearing. A satisfactory agreement between experiments and numerical calculations was obtained. Advantages and limitations of granular anchors in rock and soils were outlined.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2000, 4, 3; 517-526
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The evolution of strain localisation in a hypoplastic cosserat material under shearing
    Autorzy:
    Bauer, E.
    Huang, W.
    Powiązania:
    https://bibliotekanauki.pl/articles/1954558.pdf
    Data publikacji:
    2000
    Wydawca:
    Politechnika Gdańska
    Tematy:
    localisation
    granular materials
    polar effects
    shearing
    finite element method
    Opis:
    Numerical studies of the evolution of strain localisation and polar effects within a plane layer of a granular material under monotonic shearing are presented. Herein a micro-polar approach is formulated within the framework of a hypoplastic Cosserat continuum to describe the essential properties of a dry and cohesionless granular material like sand. The constitutive model is based on incremental non-linear tensor-valued functions and captures the influence of the pressure, the void ratio, the mean grain diameter and the rotation resistance of the grains on the evolution of the stresses and couple stresses. The Cosserat boundary conditions are suitable to model the rotation resistance at the interface between the granular layer and the surfaces adjoining the boundaries of the granular body. The numerical investigations show that the location, thickness and evolution of strain localisation within the shear layer are strongly influenced by the boundary conditions and the initial state quantities.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2000, 4, 3; 469-483
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Modelling of the pressure and density sensitive behaviour of sand within the framework of hypoplasticity
    Autorzy:
    Bauer, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/1954566.pdf
    Data publikacji:
    2000
    Wydawca:
    Politechnika Gdańska
    Tematy:
    hypoplasticity
    element test
    void ratio
    critical state
    granular materials
    Opis:
    In this paper a hypoplastic model proposed by Gudehus and Bauer is presented which is apt to describe the mechanical behaviour of loose and dense sand within a wide range of pressures and densities using a single set of constants. State changes are assumed to depend on the current void ratio, the Cauchy stress tensor and the stretching tensor. The constitutive equation is of the rate type and based on non-linear tensor-valued functions. By including a pressure dependent relative density the hypoplastic model describes the influence of pressure and density on the incremental stiffness, the peak friction angle and on the void ratio in a stationary state. The performance of the hypoplastic models is discussed and the results of numerical simulations are compared with experiments.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2000, 4, 3; 367-387
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Analysis of pressure evolution in granular materials in converging bins during filling and emptying processes
    Autorzy:
    Sielamowicz, I.
    Mróz, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/1955766.pdf
    Data publikacji:
    2003
    Wydawca:
    Politechnika Gdańska
    Tematy:
    granular materials
    pressure
    elastic and elasto-plastic model
    filling
    empting
    Opis:
    A simplified analysis of deformation and stress states in converging hoppers during filling and discharge of granular material is presented. In particular we discuss a method for solving the set of differential equations governing the flow of granular material in a plane wedge hopper. The equilibrium conditions and stress-strain relations are satisfied for the planar slice elements assuming the dependence of displacement and stress on the Cartesian coordinate z. The transient flow of an icompressible, cohesionless granular material in a two-dimensional converging hopper is considered. We assume the material to be in elastic or elasto-plastic states within the hopper satisfying the Coulomb yield condition and the non-associated flow rule. The paper presents a detailed analysis of the evolution of pressure acting on the hopper wall during the filling and emptying processes when the initial active state of pressure is transformed into a passive state. Analytical and numerical analyses are presented. It is shown that at the initial stage of the emptying process a considerable switch overpressure develops, exceeding the steady-state passive pressure several times.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2003, 7, 4; 643-666
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A comprehensive constitutive equation for granular materials
    Autorzy:
    Gudehus, G.
    Powiązania:
    https://bibliotekanauki.pl/articles/1954568.pdf
    Data publikacji:
    2000
    Wydawca:
    Politechnika Gdańska
    Tematy:
    constitutive equation of soil
    critical state
    deformation
    granular materials
    stability analysis
    Opis:
    constitutive equation is proposed for describing changes of states of granular materials, which are sufficiently characterised by the void ratio and the stress tensor. It may be considered as an extension of the Critical State concept. It is based on recently published hypoplastic equations and covers a wide range of densities, pressures and deformations. A factorial decomposition allows a rather easy separation and determination of material parameters. Two factors depend on a relative void ratio so that it remains within lower and upper bounds. The bounding void ratios decrease monotonously from maximal values to zero with increasing pressure. The same reduction of the void ratio is proposed for an isotropic compression starting from a suspension. Thus a granulate hardness is defined, and a stiffness factor can be determined. Four material parameters can be estimated from classification tests and determined from the asymptotic behaviour in element tests. Four further parameters are determined by calibration; they are rather constant for wide groups of materials. Strength and stiffness values can be derived and used for the analysis of deformations, stability, and flow. The viscous behaviour is modelled by a rate dependent factor with one further parameter. Limitations and possible extensions of this comprehensive approach are also outlined.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2000, 4, 3; 319-342
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evolution of shear localisation in earth pressure problems of a retaining wall
    Autorzy:
    Tejchman, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1986988.pdf
    Data publikacji:
    2002
    Wydawca:
    Politechnika Gdańska
    Tematy:
    earth pressure
    granular materials
    finite element method
    hypoplasticity
    polar continuum
    retaining wall
    shear localization
    Opis:
    The paper deals with numerical investigations of the evolution of shear localisation in granular bodies for earth pressure problems of a retaining wall in conditions of plane strain. The passive and active failure of a retaining wall in sand is discussed. The calculations are carried out with a rigid and very rough retaining wall undergoing horizontal translation, rotation around the top and rotation around the bottom. The behaviour of dry sand is numerically modelled with a finite element method using a hypoplastic constitutive relation within a polar (Cosserat) continuum. The constitutive relation is obtained through extension by polar quantities, viz. rotations, curvatures and couple stresses, using the mean grain diameter as a characteristic length. During FE-calculations, the attention is laid on the influence of different wall movements on shear localisation. In addition, the effects of the initial void ratio, distribution of the initial void ratio and mean grain diameter, pressure level and size of the sand body and retaining wall is investigated in the case of a passive wall translation. The FE-results are compared with corresponding experimental results of laboratory model tests.
    Źródło:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk; 2002, 6, 3; 387-410
    1428-6394
    Pojawia się w:
    TASK Quarterly. Scientific Bulletin of Academic Computer Centre in Gdansk
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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