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  • Conference paper
    Zolghadr 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 paper
    Georgiadis 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 paper
    Potts 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 paper
    Grammatikopoulou 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.

  • Journal article
    Latham J-P, Munjiza A, Mindel J, Xiang J, Guises R, Garcia X, Pain C, Gorman G, Piggott Met al., 2008,

    Modelling of massive particulates for breakwater engineering using coupled FEMDEM and CFD

    , PARTICUOLOGY, Vol: 6, Pages: 572-583, ISSN: 1674-2001
  • Conference paper
    Monroy 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 article
    Pierazzo E, Artemieva N, Asphaug E, Baldwin EC, Cazamias J, Coker R, Collins GS, Crawford DA, Davison T, Elbeshausen D, Holsapple KA, Housen KR, Korycansky DG, Wunnemann Ket al., 2008,

    Validation of numerical codes for impact and explosion cratering: Impacts on strengthless and metal targets

    , METEORITICS & PLANETARY SCIENCE, Vol: 43, Pages: 1917-1938, ISSN: 1086-9379
  • Journal article
    Bray VJ, Collins GS, Morgan JV, Schenk PMet al., 2008,

    The effect of target properties on crater morphology: Comparison of central peak craters on the Moon and Ganymede.

    , Meteoritics and Planetary Science, Vol: 43, Pages: 1979-1992
  • Journal article
    Gorman GJ, Piggott MD, Wells MR, Pain CC, Allison PAet al., 2008,

    A systematic approach to unstructured mesh generation for ocean modelling using GMT and Terreno

    , Computers & Geosciences, Vol: 34, Pages: 1721-1731, ISSN: 0098-3004

    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 article
    Collins GS, Kenkmann T, Osinski GR, Wunnemann Ket al., 2008,

    Mid-sized complex crater formation in mixed crystalline-sedimentary targets: Insight from modeling and observation

    , METEORITICS & PLANETARY SCIENCE, Vol: 43, Pages: 1955-1977, ISSN: 1086-9379
  • Journal article
    Osinski GR, Grieve RAF, Collins GS, Marion C, Sylvester Pet al., 2008,

    The effect of target lithology on the products of impact melting

    , METEORITICS & PLANETARY SCIENCE, Vol: 43, Pages: 1939-1954, ISSN: 1086-9379
  • Journal article
    Cobden L, Goes S, Cammarano F, Connolly JADet al., 2008,

    Thermochemical interpretation of one-dimensional seismic reference models for the upper mantle: evidence for bias due to heterogeneity

    , GEOPHYSICAL JOURNAL INTERNATIONAL, Vol: 175, Pages: 627-648, ISSN: 0956-540X
  • Journal article
    Wells MR, Allison PA, Hampson GJ, Piggott MD, Pain CC, Dodman Aet 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 article
    Liu 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.

  • Book
    Jardine RJ, 2008,

    Review of technical issues relating to foundations and geotechnics for offshore installations in the UKCS

    , London, Publisher: HSE Books
  • Journal article
    Schroeder FC, Jardine RJ, Kovacevic N, Potts DMet al., 2008,

    Assessing well drilling disturbance effects on offshore foundation piles in clay

    , JOURNAL OF GEOTECHNICAL AND GEOENVIRONMENTAL ENGINEERING, Vol: 134, Pages: 1261-1271, ISSN: 1090-0241
  • Journal article
    Jackson CAL, Barber GP, Martinsen OJ, 2008,

    Submarine slope morphology as a control on the development of sand-rich turbidite depositional systems: 3D seismic analysis of the Kyrre Fm (Upper Cretaceous), Maloy Slope, offshore Norway

    , MAR PETROL GEOL, Vol: 25, Pages: 663-680, ISSN: 0264-8172

    Three-dimensional seismic and well data are integrated to investigate the geometry and controls on a series of sand-rich slope systems in the Kyrre Fm (Upper Cretaceous) on the Maloy Slope, offshore Norway. Slope systems were fed by sediments eroded from mainland Norway to the east and transported across a relatively narrow shelf into four canyons developed at the shelf edge. These canyons were not formed through erosional or mass-wasting processes during the Late Cretaceous, but represent a series of underfilled canyons developed during an earlier. Late Jurassic erosional phase. Channels, which are commonly arranged into laterally or vertically stacked channel complexes, were fed sediment through the shelf-edge canyons and may be associated downslope with small terminal fans. The canyons and their associated depositional systems were not active synchronously, with a clear southward migration of the active depositional systems. On the slope, syn-depositional topography was formed via: (i) differential compaction of mudstone-rich strata across underlying Late Jurassic canyons which resulted in the formation of a series of E-W-trending structural lows; and (ii) differential compaction of mudstone-rich strata across the underlying Late Jurassic fault blocks which resulted in N-W-trending structural highs. Both of these features had a variable influence on the incision, fill and overall spatial distribution of slope channels/channel complexes and associated fans. A large fan which overlies the shelf-edge canyons and associated downslope depositional systems represents the final depositional unit within the study area. The fan effectively 'seals' the underlying shelf-edge canyons, suggesting it was not supplied by sediment routed through the canyons. The results of this study support previous studies which indicate that shelf-edge canyons may be a first-order control on the location of sand-rich, turbidity current-fed depositional systems on submarine slopes. Furthermore

  • Conference paper
    Gasparre A, Nishimura S, Anh-Minh N, Coop MR, Jardine RJet al., 2008,

    Characteristics of London Clay: stiffness and influence of structure, a summary

    , 4th International Symposium on Deformation Characteristics of Geomaterials, Publisher: IOS Press, Pages: 191-198
  • Conference paper
    Nishimura S, Jardine RJ, Brosse A, 2008,

    Simple shear testing of London Clay in hollow cylinder apparatus

    , Amsterdam, 4th International Symposium on Deformation Characteristics of Geomaterials, Publisher: IOS Press, Pages: 199-206
  • Journal article
    Jackson CA-L, 2008,

    Sedimentology and significance of an early syn-rift paleovalley, Wadi Tayiba, Suez Rift, Egypt

    , Journal of African Earth Sciences, Vol: 52, Pages: 62-68

    Wadi Tayiba is located along the western margin of the Hammam Faraun fault block, western Sinai, Egypt and is generally thought to contain exposures of the ‘type-section’ for late pre-rift to early syn-rift stratigraphy associated with the Oligo-Miocene Suez Rift. Previous studies have suggested a complex vertical succession of sedimentary facies characterise the late pre-rift to early syn-rift and imply major and abrupt variations in relative sea-level during this time. Detailed sedimentological and stratigraphic analysis of the Wadi Tayiba type-section presented in this study identifies not only a far simpler vertical facies succession than previously suggested but also the development of a major paleovalley system at the base of the early syn-rift succession. It is suggested that this subtle but significant feature is the cause of the complex vertical facies succession previously interpreted. It is concluded that continuous marine sedimentation and only moderate amplitude variations in relative sea-level occurred during the Eocene to Early Oligocene within at least this part of the Suez Rift. A major relative sea-level fall occurred during the middle Oligocene and a regionally developed erosional surface associated with this event marks the contact between late pre-rift and early syn-rift strata. The results of this study have major implications for sub-regional correlations of late pre-rift to early syn-rift stratigraphic units and resultant palaeogeographic reconstructions of the late pre-rift to early syn-rift period.

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