A study of strain localization in geomaterials using standard and non-standard continuum models
Başlık:
A study of strain localization in geomaterials using standard and non-standard continuum models
Yazar:
Yap, Tzs Yee, author.
ISBN:
9780438085176
Yazar Ek Girişi:
Fiziksel Tanımlama:
1 electronic resource (404 pages)
Genel Not:
Source: Dissertation Abstracts International, Volume: 76-08C.
Özet:
Finite elements have been identified as an appropriate way to analyse progressive failure in soils, due to their ability to model the progressive evolution of the failure mechanism. However, conventional (standard continuum) finite element solutions are element-size-dependent. That is, as the element size gets smaller, so the shearband gets narrower, and, for strain-softening soils in particular, this can lead to dramatic variations in computed structural response. Hence, this has led to the development of various nonstandard continua for combating element-size-dependency. This thesis has considered the performance of both standard and non-standard continua for a range of plane strain problems. In particular, it has investigated whether meaningful results can be obtained using conventional finite elements and standard continuum theory. Secondly, it has investigated the feasibility of using non-standard (Cosserat) continuum theory in real (large-scale) geotechnical computations. For the standard continuum, there is no convergence of the shearband thickness with decreasing element size. However, convergence of the peak and residual loads is possible, especially for larger problems in which the failure mechanism develops more gradually. In particular, in the case of the peak load, this converges at computed shearband thicknesses much larger than observed in practice. This is an important finding, since many geotechnical failures are load-induced (e.g. due to gravity). The non-standard Cosserat continuum has been successful in enabling a converged shearband thickness and load-displacement solution. However, very small elements are needed to trigger the Cosserat effect, and this fact, coupled with the extra rotational degrees of freedom used in the formulation, leads to a very significant increase in computer storage and run-time requirements, which would be prohibitive in most practical problems. Furthermore, although Cosserat theory is relatively simple to implement (at least, compared with other non-standard continua), its inability to cope with the J3 stress invariant means that it can only be used with circular yield and failure surfaces. This is a big disadvantage for geotechnical applications, especially for 3-dimensional problems, in which the Lode angle is likely to vary widely across the problem domain.
Notlar:
School code: 1543
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Yer Numarası | Demirbaş Numarası | Shelf Location | Lokasyon / Statüsü / İade Tarihi |
---|---|---|---|
XX(686935.1) | 686935-1001 | Proquest E-Tez Koleksiyonu | Arıyor... |
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