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Conference paperBell RE, 2009,
Hikurangi margin tsunami earthquake generated by slip over a subducted seamount, Geosciences '09
Journal articleBell RE, McNeill LC, Bull JM, et al., 2009,
Journal articleNishimura S, Martin CJ, Jardine RJ, et al., 2009,
Conference paperBarker DH, Sutherland R, Henrys SA, et al., 2009,
TI: Along-strike Transitions in Subduction Characteristics, Hikurangi Margin, New Zealand, AGU Fall Meeting
Conference paperZolghadr Jahromi H, Izzuddin BA, Zdravkovic L, 2008,
Computational methods in Dirichlet-Neumann coupling of soil-structure interaction, Pages: 239-245
This paper presents domain decomposition methods for nonlinear analysis of soil-structure interaction problems, where particular emphasis is given to Dirichlet-Neumann iterative coupling methods. In this approach, the overall soil-structure domain is physically decomposed into independently modelled soil and structure sub-domains, and then the response of separately modelled sub-domains is coupled by successive updates of the boundary conditions, ensuring convergence to equilibrium and compatibility at the interface of the soil-structure coupled system. In this respect, the mathematical and computational characteristics of using constant relaxation, adaptive relaxation and condensed stiffness matrix of the partitioned sub-domains in coupling algorithms are discussed, including the convergence conditions and choice of algorithmic parameters. In view of the above, the use of a modified reduced order method, which utilises an efficient approximation of the condensed stiffness matrices at the soil-structure interface to ensure and accelerate convergence, is discussed and its merits are illustrated in a case study. © 2009 Taylor & Francis Group, London.
Conference paperGrammatikopoulou A, Zdravkovic L, Potts DM, 2008,
Numerical analysis of an embankment founded on structured clay, Pages: 4041-4048
This paper presents the numerical analysis of an embankment founded on a soft structured clay deposit. The paper investigates the effect of modelling the destructuration of the natural clay foundation. A comparison of the embankment behaviour is presented when its soft clay foundation is modelled with a new constitutive model, which can account for destructuration in natural clays and a pre-existing model applicable to reconstituted clays. The paper demonstrates that taking account of the destructuration of the soft clay foundation results in a lower embankment failure height and a different failure surface.
Conference paperPotts VJ, Zdravković L, 2008,
Finite element analysis of arching behaviour in soils, Pages: 3642-3649
Based on the results of a parametric study investigating the behaviour of geosynthetic reinforced fill load transfer platforms above voids, using finite element analysis, a review of the nature of the soil arching that develops in the fill has been undertaken. The fill response to the formation of a void is compared with arching theories developed by Terzaghi (1943) and Hewlett and Randolph (1988). It is found that Terzaghi's approach is capable of describing all of the behaviour seen when a stable arch forms, whereas Hewlett and Randolph's formulation may only be applied to a limited number of cases. It is also found that the accuracy with which Terzaghi's approach predicts the vertical stress at the base of the fill layer depends on the value of the stress ratio K in the shear zone. Owing to the high level of disturbance in this zone, it is difficult to determine the value of K, but it is seen that the theoretical values suggested in the literature are too low and the vertical stress at the base of the fill layer is overestimated as a result. A suitable value of K is suggested from the numerical results, which is independent of the shape and size of the void, and of the fill and geosynthetic properties.
Conference paperGeorgiadis K, Potts DM, Zdravkovic L, 2008,
An improved constitutive model for unsaturated and saturated soils, Pages: 581-588
This paper presents a constitutive model for unsaturated and saturated soils based on the critical state framework. The model includes a versatile expression for yield and plastic potential surfaces, the option of linear or nonlinear increase of shear strength with suction and three options for the shape of the unsaturated isotropic compression lines. The latter feature is of particular importance as it controls the amount of potential collapse the soil can experience due to wetting. Depending on the type of boundary value problem analysed a linear, bi-linear or exponential relationship can be used. Two sets of finite element analyses are presented here which investigate the influence of the shape of the isotropic compression line on the behaviour of strip footings and axially loaded single piles. © 2008 Taylor & Francis Group, London.
Conference paperMonroy R, Zdravkovic L, Ridley A, 2008,
Volumetric behaviour of compacted London Clay during wetting and loading, Pages: 315-320
In this study, the mechanical behaviour of a compacted clay in equilibrium with the atmospheric pressure was investigated. Samples of London Clay were compacted to the same initial conditions, corresponding to dry of optimum moisture content on a Proctor plot, and were taken along complex stress paths, involving wetting under a constant vertical stress, wetting under a condition of zero volumetric strain, and loading and unloading at a constant value of matric suction. Tests were performed with a combination of standard and osmotic oedometers-the latter developed specifically at Imperial College London to test unsaturated soils under atmospheric conditions. Samples taken along different hydration paths displayed similar post-yield behaviour when loaded at a constant suction, suggesting that common yield surface in the e: s: σv space (where e denotes void ratio, s is the matric suction, and σv is the vertical stress) controls the plastic volumetric behaviour of unsaturated London Clay during loading following monotonic hydration. © 2008 Taylor & Francis Group, London.
Journal articleOsinski GR, Grieve RAF, Collins GS, et al., 2008,
Journal articlePierazzo E, Artemieva N, Asphaug E, et al., 2008,
Journal articleBray VJ, Collins GS, Morgan JV, et al., 2008,
Journal articleCollins GS, Kenkmann T, Osinski GR, et al., 2008,
Journal articleGorman GJ, Piggott MD, Wells MR, et al., 2008,
A systematic approach to unstructured mesh generation for ocean modelling is presented. The method optimises unstructured meshes to approximate bathymetry to a user specified accuracy which may be defined as a function of longitude, latitude and bathymetry. GMT (Generic Mapping Tools) is used to perform the initial griding of the bathymetric data. Subsequently, the Terreno meshing package combines automated shoreline approximation, mesh gradation and optimisation methods to generate high-quality bathymetric meshes. The operation of Terreno is based upon clearly defined error measures and this facilitates the automation of unstructured mesh generation while minimising user intervention and the subjectivity that this can introduce.
Journal articleLatham J-P, Munjiza A, Mindel J, et al., 2008,
Journal articleWells MR, Allison PA, Hampson GJ, et al., 2008,
Investigating tides in the Early Pennsylvanian Seaway of NW Eurasia using the Imperial College Ocean Model, Geological Association of Canada Special Paper, Vol: 48, Pages: 363-387, ISSN: 0072-1042
Journal articleCobden L, Goes S, Cammarano F, et al., 2008,
Journal articleLiu J-G, Yan H, 2008,
Phase correlation pixel-to-pixel image co-registration based on optical flow and median shift propagation, International Journal of Remote Sensing, Vol: 29, Pages: 5943-5956
With singular value decomposition (SVD) and robust 2-dimensional fitting phase correlation algorithms, it is possible to achieve pixel-to-pixel image coregistration at sub-pixel accuracy via local feature matching. However, the method often fails in featureless and low correlation areas making it not robust for co-registration of images with considerable spectral differences and large featureless ground objects. A median shift propagation (MSP) technique is proposed to eliminate the problem, in a phase correlation and Normalized Cross- Correlation (NCC) combined approach. The experiment results using images from different sensor platforms and spectral bands indicate that the new method is very robust to featureless and low correlation areas and can achieve very accurate pixel-to-pixel image co-registration with good tolerance of spectral and spatial differences between images. The method will significantly improve change detection in various remote sensing applications.
BookJardine RJ, 2008,
Review of technical issues relating to foundations and geotechnics for offshore installations in the UKCS, London, Publisher: HSE Books
Conference paperGasparre A, Coop MR, Jardine RJ, 2008,
Effects of recent stress history on a stiff natural clay, Amsterdam, 4th International Symposium on Deformation Characteristics of Geomaterials, Publisher: IOS Press, Pages: 207-214
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