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  • Journal article
    Kontoe S, Zdravkovic L, Potts DM, Menkiti COet al., 2011,

    On the relative merits of simple and advanced constitutive models in dynamic analysis of tunnels

    , Geotechnique, Vol: 61, Pages: 815-829, ISSN: 0016-8505

    This paper compares simple constitutive models that are widely used in engineering practice with more sophisticated methods in the context of a case study. In particular, four constitutive modelling approaches have been considered: a simple elasto-plastic constitutive model (modified Cam-clay), with and without Rayleigh damping; the same model coupled with a cyclic non-linear model that can simulate pre-yield hysteresis; and finally an advanced kinematic hardening model, which is an improved version of the Al-Tabbaa & Wood two-surface model. These four approaches are used to analyse the seismic response of a section of the Bolu tunnels during the 1999 Duzce earthquake. To shed light on the performance of the constitutive models, simple site response finite-element analyses were first undertaken for the studied site, paying particular attention to the calibration of the Rayleigh damping parameters. The results of these analyses, in terms of maximum shear strain, were then used as input to an analytical elastic method (extended Hoeg method) for calculating the thrust and bending moment acting in the tunnel lining. Finally the results of dynamic time domain plane-strain analyses, employing the four adopted constitutive modelling approaches, are compared against field observations and results obtained by the extended Hoeg method, to investigate the ability of the models, of ranging complexity, to mimic soil response under seismic excitation.
  • Journal article
    Farrell PE, Piggott MD, Gorman GJ, Ham DA, Wilson CR, Bond TMet al., 2011,

    Automated continuous verification for numerical simulation

    , Geoscientific Model Development, Vol: 4, Pages: 435-449
  • Journal article
    Foulser-Piggot R, Stafford PJ, 2011,

    A predictive model for Arias intensity at multiple sites and consideration of spatial correlations

    , Earthquake Engineering & Structural Dynamics
  • Journal article
    Sgobba S, Stafford PJ, Marano GC, Guaragnella Cet al., 2011,

    An evolutionary stochastic ground-motion model defined by a seismological scenario and local site conditions

    , Soil Dynamics and Earthquake Engineering
  • Journal article
    Morgan JV, Warner MR, Collins GS, Grieve RAF, Christeson GL, Gulick SPS, Barton PJet al., 2011,

    Full waveform tomographic images of the peak ring at the Chicxulub impact crater

    , Journal of Geophysical Research, Vol: 116

    Peak rings are a feature of large impact craters on the terrestrial planets and are generally believed to be formed from deeply buried rocks that are uplifted during crater formation. The precise lithology and kinematics of peak ring formation, however, remains unclear. Previous work has revealed a suite of bright inward-dipping reflectors beneath the peak ring at the Chicxulub impact crater and that the peak ring was formed from rocks with a relatively low seismic velocity. New 2D full-waveform tomographic velocity images show that the uppermost lithology of the peak ring is formed from a thin (~100-200 m thick) layer of low-velocity (~3000-3200 m/s) rocks. This low-velocity layer is most likely to be composed of highly porous, allogenic impact breccias. Our models also show that the change in velocity between lithologies within and outside the peak ring is more abrupt than previously realized and occurs close to the location of the dipping reflectors. Across the peak ring, velocity appears to correlate well with predicted shock pressures from a dynamic model of crater formation, where the rocks that form the peak ring originate from uplifted basement that has been subjected to high shock pressures (10-50 GPa), and lie above downthrown sedimentary rocks that have been subjected to shock pressures of < 5 GPa. These observations suggest that low-velocities within the peak ring may be related to shock effects and that the dipping reflectors underneath the peak ring might represent the boundary between highly-shocked basement and weakly-shocked sediments.
  • Journal article
    Gowen RA, Smith A, Fortes AD, Barber S, Brown P, Church P, Collinson G, Coates AJ, Collins G, Crawford IA, Dehant V, Chela-Flores J, Griffiths AD, Grindrod PM, Gurvitis LI, Hagermann A, Hussmann H, Jaumann R, Jones AP, Joy KH, Karatekin O, Miljkovic K, Palomba E, Pike WT, Prieto-Ballesteros O, Raulin F, Sephton MA, Sheridan S, Sims M, Storrie-Lombardi MC, Ambrosi R, Fielding J, Fraser G, Gao Y, Jones GH, Kargl G, Karl WJ, Macagnano A, Mukherjee A, Muller JP, Phipps A, Pullan D, Richter L, Sohl F, Snape J, Sykes J, Wells Net al., 2011,

    Penetrators for in situ subsurface investigations of Europa

    , ADV SPACE RES, Vol: 48, Pages: 725-742, ISSN: 0273-1177

    We present the scientific case for inclusion of penetrators into the Europan surface, and the candidate instruments which could significantly enhance the scientific return of the joint ESA/NASA Europa-Jupiter System Mission (EJSM). Moreover, a surface element would provide an exciting and inspirational mission highlight which would encourage public and political support for the mission.Whilst many of the EJSM science goals can be achieved from the proposed orbital platform, only surface elements can provide key exploration capabilities including direct chemical sampling and associated astrobiological material detection, and sensitive habitability determination. A targeted landing site of upwelled material could provide access to potential biological material originating from deep beneath the ice.Penetrators can also enable more capable geophysical investigations of Europa (and Ganymede) interior body structures, mineralogy, mechanical, magnetic, electrical and thermal properties. They would provide ground truth, not just for the orbital observations of Europa, but could also improve confidence of interpretation of observations of the other Jovian moons. Additionally, penetrators on both Europa and Ganymede, would allow valuable comparison of these worlds, and gather significant information relevant to future landed missions. The advocated low mass penetrators also offer a comparatively low cost method of achieving these important science goals.A payload of two penetrators is proposed to provide redundancy, and improve scientific return, including enhanced networked seismometer performance and diversity of sampled regions.We also describe the associated candidate instruments, penetrator system architecture, and technical challenges for such penetrators, and include their current status and future development plans.
  • Journal article
    Whitchurch AL, Carter A, Sinclair HD, Duller RA, Whittaker AC, Allen PAet al., 2011,

    Sediment routing system evolution within a diachronously uplifting orogen: Insights from detrial zircon thermochronological analyses from the South-Central Pyrenees

    , AMERICAN JOURNAL OF SCIENCE, Vol: 311, Pages: 442-482
  • Journal article
    Funke SW, Pain CC, Kramer SC, Piggott MDet al., 2011,

    A wetting and drying algorithm with a combined pressure/free-surface formulation for non-hydrostatic models

    , Advances in Water Resources
  • Conference paper
    van Reeuwijk M, Hunt GR, Jonker HJJ, 2011,

    Direct simulation of turbulent entrainment due to a plume impinging on a density interface
  • Journal article
    Vinogradov J, 2011,

    Multiphase streaming potential in sandstones saturated with gas/brine and oil/brine during drainage and imbibition

    , Geophysical Research Letters
  • Journal article
    Bell RE, McNeill LM, Henstock T, Bull JMet al., 2011,

    Comparing extension on multiple time and depth scales in the Corinth Rift, Central Greece

    , Geophysical Journal International, Vol: 186, Pages: 463-470
  • Conference paper
    Camara A, Ruiz-Teran AM, Stafford PJ, Ciupala MAet al., 2011,

    Non-linear behaviour of under-deck cable-stayed bridges

    , IABSE-IASS 2011 Symposium
  • Conference paper
    Milthaler F, Xiang J, Pavlidis D, Latham J-P, Pain CC, Vire A, Piggott MDet al., 2011,

    The immersed body method combined with mesh adaptivity for solid-fluid coupling

    , 6th International Conference on Coastal Structures
  • Conference paper
    Bell RE, Sutherland R, Henrys S, Wallace L, Beavan Jet al., 2011,

    Characterisation of the Hikurangi subduction margin, North Island, New Zealand

    , British Geophysical Association New Advances in Geophysics meeting
  • Conference paper
    Bell RE, McNeill L, Bull J, Henstock Tet al., 2011,

    Fault development and syn-rift basin structure within the Corinth Rift, Greece

    , American Association of Petroleum Geologists Annual Conference and Exhibition
  • Conference paper
    Bell RE, Sutherland R, Henrys SA, Wallace LM, Barker DH, Bannister SC, Beavan RJet al., 2011,

    Seismic reflection character of the Hikurangi subduction megathrust, North Island, New Zealand INVITED

    , American Geophysical Union, Fall Meeting
  • Conference paper
    Williams CA, Wallace LM, Beavan RJ, Lohman RB, Ellis SM, Marson-Pidgeon K, Eberhart-Phillips DM, Reyners M, Henrys SA, Bell REet al., 2011,

    Modeling of Slow Slip Events at the Hikurangi Subduction Margin

    , AGU Fall Meeting
  • Journal article
    Wuennemann K, Collins GS, Weiss R, 2010,

    IMPACT OF A COSMIC BODY INTO EARTH'S OCEAN AND THE GENERATION OF LARGE TSUNAMI WAVES: INSIGHT FROM NUMERICAL MODELING

    , REVIEWS OF GEOPHYSICS, Vol: 48, ISSN: 8755-1209
  • Conference paper
    Bournta Z, Zdravkovic L, 2010,

    Bearing capacity of a surface footing founded on a layered clay subsoil

    , Pages: 553-556

    The ultimate bearing capacity of surface footings resting on homogeneous soils has been studied extensively. Real soil strength profiles beneath footings, however, are not homogeneous but may increase or decrease with depth, or consist of distinct layers having significantly different properties. The current study focuses on the application of the finite element method for the evaluation of the ultimate bearing capacity of a rough rigid footing resting on a layered clay profile. Computations are performed using the finite element analysis software ICFEP (Imperial College Finite Element Program). One set of parametric analyses is carried out for the case of strip and circular footings resting on soft clay overlying stiff clay, in order to examine the effect of the vicinity of the strong clay layer on the bearing capacity factor. Another set of parametric analyses is performed for the case of circular footings resting on a multi-layered soil profile that includes a layer of soft clay resting within the strong clay subsoil, in order to investigate the effect of both the vicinity and the thickness of the soft clay layer on the bearing capacity factor. In both cases comparison of the analyses results with the literature has been made. © 2010 Taylor & Francis Group, London.
  • Conference paper
    Grammatikopoulou A, Kovacevic N, Zdravkovic L, Potts DMet al., 2010,

    Finite element analysis of the main embankment at Empingham dam

    , Pages: 557-562

    Empingham dam is a 37m high earth fill embankment which was constructed in the UK in the early 1970's. The embankment was built on a brecciated Upper Lias Clay (ULC) foundation, of fill derived from it. The ULC is a typical stiff plastic clay which shows a post-peak strength loss and as such is prone to progressive failure. The paper describes the finite element back analyses of the embankment behaviour during construction, using a kinematic hardening "bubble" model which accounts for both pre-peak plasticity and post-peak strain softening. © 2010 Taylor & Francis Group, London.

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