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  • Conference paper
    Taborda D, Zdravkovic L, Kontoe S, Potts DMet al., 2010,

    Alternative formulations for cyclic nonlinear models: parametric study and comparative analyses

    , 7th European Conference on Numerical Methods in Geotechnical Engineering, Pages: 423-428

    The utilisation of cyclic nonlinear elastic models presents numerous advantages when analysingsimple dynamic problems, such as one-dimensional site response. This class of models requires a small numberof parameters to be determined and can efficiently reproduce the strain dependency of the secant shear stiffnessand hysteretic damping. However, it has been frequently noted that, for medium to large deformation levels, thepredicted damping ratio can be significantly larger than the values evaluated for most soils through laboratorytesting. To minimise the effects of this overestimation on the overall response of the system, which may lead tonon conservative results, different formulations have been proposed. In this paper, two alternative expressionsfor the stress-strain behaviour of soils – hyperbolic and logarithmic – are presented and their ability to reproducewell-established empirical stiffness degradation and damping ratio curves is assessed. Finally, the results of a setof dynamic finite element analyses of a one-dimensional wave propagation problem are presented to illustratethe impact of the different formulations on the engineering behaviour of soil deposits.
  • Conference paper
    Papaspiliou M, Kontoe S, Bommer J, 2010,

    Site Response Analysis Incorporated in Probabilistic Seismic Hazard Assessments

    , 9th US National and 10th Canadian Conference on Earthquake Engineering, Publisher: EERI
  • Journal article
    Jackson CA-L, Kane KE, Larsen E, 2010,

    Structural evolution of minibasins on the Utsira High, northern North Sea; implications for Jurassic sediment dispersal and reservoir distribution

    , Petroleum Geoscience, Vol: 16, Pages: 105-120

    3D seismic and well data are integrated to determine the tectonostratigraphicevolution of the SW margin of the Utsira High, northern North Sea riftsystem. During the Triassic, a series of minibasins formed due to passive diapirismof the evaporite-bearing, Upper Permian, Zechstein Supergroup. Subsequently,during the Jurassic, a series of secondary minibasins developed as the underlying saltwalls collapsed. These minibasins were a few hundred metres deep, bound bysub-circular to elongate salt-cored structural highs and caused the development ofcomplex subaerial topography and submarine bathymetry on the SW margin of theUtsira High. Salt withdrawal may have been related to: (i) partial dissolution of salt;(ii) differential erosion of the salt walls and adjacent Triassic-filled minibasins; or (iii)salt remigration caused by sub- or supra-salt extension or sediment loading. Thisstudy provides insights into the tectono-stratigraphic evolution of the SW margin ofthe Utsira High and has implications for (i) facies distribution of the ZechsteinSupergroup within the northern North Sea rift system; and (ii) depositional systemdevelopment, and thus reservoir distribution, within the Jurassic sedimentarysuccession.
  • Conference paper
    Henrys SA, Sutherland R, Seward A, Hendersen M, Stern TA, Savage MK, Townend J, Mochizuki K, Sato H, Iwasaki T, Bassett D, Bell REet al., 2010,

    The 2009-2010 SAHKE Experiment: Acquisition and preliminary results across the interseismically locked southern Hikurangi margin, New Zealand

    , American Geophysical Union Fall Meeting
  • Journal article
    Garcia X, Pavlidis D, Gorman GJ, Gomes JLMA, Piggott MD, Aristodemou E, Mindel J, Latham JP, Pain CC, ApSimon Het al., 2010,

    A two-phase adaptive finite element method for solid–fluidcoupling in complex geometries

    , International Journal for Numerical Methods in Fluids

    In this paper we present a method to solve the Navier–Stokes equations in complex geometries, suchas porous sands, using a finite-element solver but without the complexity of meshing the porous space.The method is based on treating the solid boundaries as a second fluid and solving a set of equationssimilar to those used for multi-fluid flow. When combined with anisotropic mesh adaptivity, it is possibleto resolve complex geometries starting with an arbitrary coarse mesh. The approach is validated bycomparing simulation results with available data in three test cases. In the first we simulate the flow pasta cylinder. The second test case compares the pressure drop in flow through random packs of sphereswith the Ergun equation. In the last case simulation results are compared with experimental data on theflow past a simplified vehicle model (Ahmed body) at high Reynolds number using large-eddy simulation(LES). Results are in good agreement with all three reference models.
  • Journal article
    Mitchell AJ, Allison PA, Piggott MD, Gorman GJ, Pain CC, Hampson GJet al., 2010,

    Numerical modelling of tsunami propagation with implications for sedimentation in ancient epicontinental seas: the Lower Jurassic Laurasian Seaway

    , Journal of Sedimentary Geology, Vol: 228, Pages: 81-97, ISSN: 0037-0738
  • Journal article
    Farrell PE, Piggott MD, Gorman GJ, Ham DA, Wilson CRet al., 2010,

    Automated continuous verification and validation for numerical simulation

    , Geoscientific Model Development Discussions, Vol: 3, Pages: 1587-1623
  • Conference paper
    Foulser-Piggott R, Stafford PJ, 2010,

    Incorporation of the spatial correlation of Arias intensity within Earthquake Loss Estimation

    , 5th International Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics
  • Journal article
    Buratti N, Stafford PJ, Bommer JJ, 2010,

    Earthquake accelerogram selection and scalingprocedures for estimating the distribution of structural response

    , Journal of Structural Engineering - ASCE
  • Journal article
    Bal IE, Bommer JJ, Stafford PJ, Crowley H, Pinho Ret al., 2010,

    The influence of geographicalresolution of urban exposure data in an Earthquake Loss Model

    , Earthquake Spectra
  • Journal article
    Walker C, Stafford PJ, 2010,

    The use of modal combination rules with cable-stayedbridges

    , Proceedings of the Institution of Civil Engineers - Bridge Engineering
  • Journal article
    Mitchell AJ, Ulicny D, Hampson GJ, Allison PA, Gorman GJ, Piggott MD, Wells MR, Pain CCet al., 2010,

    Modelling tidal current-induced bed shear stress and palaeocirculation in an epicontinental seaway: the Bohemian Cretaceous Basin, Central Europe

    , Sedimentology, Vol: 57, Pages: 359-388, ISSN: 0037-0746
  • Journal article
    Vinogradov J, Jaafar MZ, Jackson MD, 2010,

    Measurement of Streaming Potential Coupling Coefficient in Sandstones Saturated with Natural and Artificial Brines at High Salinity

    , Journal of Geophysical Research
  • Journal article
    Bommer JJ, Stafford PJ, Akkar S, 2010,

    Current empirical ground-motion prediction equations for Europe and their application to Eurocode 8

    , Bulletin of Earthquake Engineering, Vol: 8, Pages: 5-26
  • Conference paper
    Dorra EM, Stafford PJ, Elghazouli AY, 2010,

    Seismic loss assessment for buildings and infrastructure in Greater Cairo

    , 14th European Conference on Earthquake Engineering
  • Journal article
    Elbeshausen D, Wuennemann K, Collins GS, 2009,

    Scaling of oblique impacts in frictional targets: Implications for crater size and formation mechanisms

    , ICARUS, Vol: 204, Pages: 716-731, ISSN: 0019-1035
  • Conference paper
    Schütz R, Potts DM, Zdravković L, 2009,

    A constitutive model for the behaviour of shotcrete

    , Pages: 49-60

    A constitutive model for the behaviour of shotcrete is presented in this paper. It is formulated within the framework of elasto-plasticity and the smeared crack concept is applied. Two independent yield surfaces govern the mechanical behaviour under compression and tension, which is further controlled by non-linear hardening and softening. The main material parameters are assumed to change with time. Validation of the model has been achieved by fitting the increase in stiffness and strength to published data in the literature. Good agreement is found between predictions of the complete stress-strain curves of shotcrete at different ages and experimental results. The model represents a sophisticated tool for the realistic analysis of tunnels, which are driven according to the principles of the New Austrian Tunnelling Method (NATM).
  • Journal article
    Jackson CA-L, Johnson HD, Zakaria AA, Tongkul F, Crevello PDet al., 2009,

    Sedimentology, stratigraphic occurrence and origin of linked debrites in the West Crocker Fm (Oligo-Miocene), Sabah, NW Borneo

    , Marine and Petroleum Geology, Vol: 26, Pages: 1957-1973

    The West Crocker Fm (Oligocene-Early Miocene), NW Borneo, consists of a large (>20000 km2) submarine fan deposited as part of an accretionary complex. A range of gravity-flow deposits are observed, the most significant of which are mud-poor, massive sandstones interpreted as turbidites and clast-rich, muddy sandstones and sandy mudstones interpreted as debrites. An upward transition from turbidite to debrite is commonly observed, with the contact being either gradational and planar, or sharp and highly erosive. Their repeated vertical relationship and the nature of the contact between them, these intervals are interpreted as being deposited from one flow event which consisted of two distinct flow phases (fully turbulent turbidity current and weakly turbulent to laminar debris flow). The associated bed is called a co-genetic turbidite-debrite, with the upper debrite interval termed a linked debrite. Linked debrites indicates are best developed in the non-channelised parts of the fan system, and are absent to poorly-developed in the proximal channel-levee and distal basin floor environments. Due to outcrop limitations, the genesis of linked debrites within the West Crocker Formation is unclear. Based on clast size and type, it seems likely that a weakly turbulent to laminar debris-flow flow phase was present when the flow event entered the basin. A change in flow behaviour may have led to deposition of a sand-rich unit with ‘turbidite’ characteristics, which was subsequently overlain by a mud-rich unit with ‘debrite’ characteristics. Flow transformation may have been enhanced by the disintegration and incorporation into the flow of muddy clasts derived from the upstream channel floor, channel mouth or from channel levee collapse. Lack of preservation of this debrite in proximal areas may indicate either bypass of this flow phase or that the available outcrops fail to capture the debris flow entry point. Establishing robust sedimentological c
  • Journal article
    Aas TE, Howell JA, Janocko M, Jackson CA-Let al., 2009,

    Control of Aptian palaeobathymetry on turbidite distribution in the Buchan Graben, Outer Moray Firth, Central North Sea

    , Marine and Petroleum Geology, Vol: 27, Pages: 412-434

    It is widely recognized that palaeobathymetry is a key control on the distribution of turbidite deposits. Thus, the utilisation of palaeobathymetric surfaces as an input for numerical turbidity current modelling offers a potentially powerful method to predict the distribution of deep marine sands in ancient (subsurface or outcrop) successions. Such an approach has been tested on an Aptian turbidite deposit from the Buchan Graben, UK Central North Sea, where modelled sand distributions could be quality controlled against available well data. Palaeobathymetric (base Aptian sand) surfaces are re-created from a surface-based 3D model by stepwise backstripping of post-Aptian overburden and removal of the post-depositional structural overprint. Key input parameters such as; (i) initial porosity and compaction factor assigned to the overburden and underburden; (ii) the restoration of structural overprint; and (iii) and the crustal response to removal of overburden (Airy vs. Flexural Isostasy), are associated with significant uncertainty. Thus, to assess this uncertainty, various palaeobathymetric surfaces are re-created by systematically modelling extreme values of individual input parameters. The effects of single input parameter variability on output surface morphology are quantified by spatial comparison of appropriate surfaces. Out of the 20 palaeobathymetric surfaces that were re-created, 3 were selected as input for process-based, numerical turbidity current simulations. The simulation software (Flow 3D™) uses computational fluid-dynamics (CFD) to model depositional patterns, while the effects of flow turbulence are simulated using the Renormalization-Group (RNG) model. The location of flow introduction into the model (sediment input point) as well as flow input parameters (volume of sediment, duration of flow, velocity, height and width) are fixed for all three surfaces to ensure that differences in flow behaviour and sand distribution can be attributed to spa
  • Journal article
    Piggott MD, Farrell PE, Wilson CR, Gorman GJ, Pain CCet al., 2009,

    Anisotropic mesh adaptivity for multi-scale ocean modelling

    , PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES, Vol: 367, Pages: 4591-4611, ISSN: 1364-503X

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