摘要:

AbstractOne major problem encountered when using the finite element method to simulate the load–deformation behaviour of an elasto‐plastic soil mass is that the theoretical collapse load is generally exceeded, and in some cases the numerical solution fails to exhibit a collapse load. A mixed variational principle is used as the basis for developing the governing equations of deformation and the results from this are compared with those obtained from the use of the virtual power equation. The former is found to give improved results and is generalized to include description of finite deformation. An Eulerian frame of reference is used. The method of approximating configuration changes in the numerical solution procedure is found to determine the shape of the load–deformation curve. Finally, a simple method of accounting for anisotropy of yield is pres

ISSN:0363-9061    

DOI:10.1002/nag.1610040102

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractA finite element model for the prediction of discrete fracture propagation in rock structures loaded in compression is presented. The model integrates any one of three theories for mixed‐mode fracture initiation; it contains an energy balance algorithm for predicting crack increment length, and incorporates recent developments in finite element stress‐intensity factor computation. The predictions of the model are compared with the observed fracture response of a real rock structure. Results show that the model accurately predicts both stable and unstable fracture progagations observed experimenta

ISSN:0363-9061    

DOI:10.1002/nag.1610040103

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractA comparative discussion of constitutive rate equations generated by using the hypoelasticity and plasticity theories is presented. If is shown that these two approaches are equivalent for the loading process but differ essentially in defining the unloading (or reverse loading) paths. The multisurface plasticity formulation proves to be more convenient in incorporating memory rules of particular loading events, whereas loading‐unloading criteria used in hypoelasticity may result in an unrealistic prediction of material response for some loading paths, and in particular, for cyclic loading. The violation of the continuity condition between loading–unloading domains in proposed constitutive relations3,4limits their applicability to some particular classes of loading pa

ISSN:0363-9061    

DOI:10.1002/nag.1610040104

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractThe settlement and excess pore pressure are calculated for a column of water‐saturated clay in which the permeability and/or shear modulus vary with depth. Several fairly general laws of variation are investigated. In each case, the soil is assumed to have a permeable top surface and to rest on an impervious substrate.For all the variations examined, in which the shear modulus increases with depth below the surface but the permeability of the soil remains constant, the deflection at a given instant after imposition of the load decreases and the degree of settlement increases with increasing rate at which the change with depth takes place. It is found that, when the variation over the height of the column is one order of magnitude or less, the curve of degree‐of‐consolidationversustime is reasonably wellapproximated by the curve for a homogeneous soil whose modulus equals the depth‐averaged value. When, in addition, the permeability decreases with depth, the approximation becomes less accurate.The same approximation, for moderate increase in shear modulus with depth, predicts satisfactorily the process of dissipation of excess pore pressure at a given depth, but breaks down when the variation in modulus is large.Finally, it is shown that the effect of variable modulus on the settlement is greater than of a comparable variation in perme

ISSN:0363-9061    

DOI:10.1002/nag.1610040105

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractWe continue our study of the consolidation of inhomogeneous clay soils with an analysis of the response of a soil mass, whose shear modulus increases linearly with depth, to axially symmetric pressure on its surface. This extends the work reported in Part I on the corresponding one‐dimensional problem of a clay column, and generalizes researches of Gibson and coworkers on the elastic model of the soil (i.e., the initial response).Because of great mathematical complexity when Poisson's ratio is allowed to assume arbitrary values, we have confined ourselves (as did Gibson in several of his papers) to variations of the modulus from a zero surface value, this being in reasonable accord with published test results on London clay. The deflection of points within this region, the deflection relative to the central one (that is, the shape of the deformed loading area), as well as the absolute deflection of surface points exterior to the loa

ISSN:0363-9061    

DOI:10.1002/nag.1610040106

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

摘要:

AbstractWhen using numerical methods in soil mechanics, one often needs to define a yield surface in three‐dimensional principal‐stress space. A special class of yield surfaces, given byJ= (p+a)α(1−β sin 3ν)n, where ν is the Lode angle, is considered from the point of view of convexity and agreement with experimental data. Some recently proposed yield functions which belong to this class are compared. It is shown that the model withn= −0.229 is optimal as regards convexity, and can give reasonable agreement wi

ISSN:0363-9061    

DOI:10.1002/nag.1610040107

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY

ISSN:0363-9061    

DOI:10.1002/nag.1610040101

出版商:John Wiley&Sons, Ltd    

年代:1980

数据来源: WILEY