摘要:

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‐analy

ISSN:0363-9061    

DOI:10.1002/nag.1610110202

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

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 lan

ISSN:0363-9061    

DOI:10.1002/nag.1610110203

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

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 rese

ISSN:0363-9061    

DOI:10.1002/nag.1610110204

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractThe stability and deformation of the seafloor in response to storm wave loading is an important consideration in the design of pipelines, anchors, and offshore structures such as gravity‐and pile‐supported platforms. Two quite different approaches have been proposed for investigating the effects of storm waves on seafloor sands. These approaches derive from quite different considerations of soil‐water interaction.In one of these approaches (exemplified by Yamamoto and Madsen) the seafloor is visualized to be a porous elastic or Coulomb‐damped porous nonlinear medium. In this approach, the response of the seafloor, i.e. the displacements, stresses and porewater pressures, are computed for a given wave. The response is transient and is, therefore, related to the largest wave in the storm wave group.On the other hand, in the approach proposed by Seed and Rahman, only the development of residual porewater pressures (for estimating liquefaction potential) due to the storm wave group are considered. The effects of transient porewater pressures and stresses on the seafloor sands are ignored. The residual porewater pressures are computed using properties based on initial effective stresses through a porewater generation‐dissipation model.The application of these techniques to problems of offshore structures such as pile‐supported platforms has led to considerable uncertainty and confusion. In this paper, both of these approaches are combined to investigate seafloor response to a storm wave group. For typical storm wave conditions that exist in the North Sea, it appears that the inclusion of damping, inertia and anisotropic permeabilities in the study is not important relative to ocean sands. Parametric studies show that, for a given wave, the thickness and the stiffness properties of the soil deposit dictate the response of the deposit. The displacements in the deposit are, therefore, affected by the generation of residual porewate

ISSN:0363-9061    

DOI:10.1002/nag.1610110205

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

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 sea

ISSN:0363-9061    

DOI:10.1002/nag.1610110206

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

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.

ISSN:0363-9061    

DOI:10.1002/nag.1610110207

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractTriaxial fracture tests with overburden pressures ranging from 0.69 to 136 MPa were performed to determine the material parameters involved in a cap model for limestone. Three material parametersA, BandC, were evaluated through Powell's optimization method and the remaining parameters through simulation‐curve fitting procedure. The resulting cap model was tested against separate triaxial fracture and hydrostatic compression tests. Modification of the original hardening function, as proposed by DiMaggio and Sandler, provided an improved fit for the experimental dat

ISSN:0363-9061    

DOI:10.1002/nag.1610110208

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

摘要:

AbstractTheoretical formulations to the problem of expansion of spherical and cylindrical cavities in a layered elastic system are presented. The medium surrounding the cavity is assumed to consist of several layers, and each is idealized as a linear elastic solid. The solutions are expressed in matrix forms and can be obtained using a programmable calculator. The developed solutions are of some importance in geomechanics. The spherical cavity solution can be used to compute the settlement of single axially loaded piles. The predicted settlement using the analysis outlined herein agrees reasonably well with one case of field measurements. The cylindrical cavity solution can be used to manifest the effect of disturbed mass at the cavity wall on the stress–strain and deformation characteristics of the intact mas

ISSN:0363-9061    

DOI:10.1002/nag.1610110209

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610110210

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610110211

出版商:John Wiley&Sons, Ltd    

年代:1987

数据来源: WILEY