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  • JOURNAL ARTICLE
    Bora SS, Scherbaum F, Kuehn N, Stafford P, Edwards Bet al., 2015,

    Development of a Response Spectral Ground-Motion Prediction Equation (GMPE) for Seismic-Hazard Analysis from Empirical Fourier Spectral and Duration Models

    , BULLETIN OF THE SEISMOLOGICAL SOCIETY OF AMERICA, Vol: 105, Pages: 2192-2218, ISSN: 0037-1106
  • CONFERENCE PAPER
    Byrne BW, McAdam R, Burd HJ, Houlsby GT, Martin CM, Zdravković L, Taborda DMG, Potts DM, Jardine RJ, Sideri M, Schroeder FC, Gavin K, Doherty P, Igoe D, Muirwood A, Kallehave D, Skov Gretlund Jet al., 2015,

    New design methods for large diameter piles under lateral loading for offshore wind applications

    , Pages: 705-710

    © 2015 Taylor and Francis Group, London. Offshore wind turbines are typically founded on single large diameter piles, termed monopiles. Pile diameters of between 5mand 6mare routinely used, with diameters of up to 10 m, or more, being considered for future designs. There are concerns that current design approaches, such as the p − y method, which were developed for piles with a relatively large length to diameter ratio, may not be appropriate fo r large diameter monopiles. A joint industry project, PISA (PIle Soil Analysis), has been established to develop new design methods for large diameter monopiles under lateral loading. The project involves three strands of work; (i) numerical modelling; (ii) development of a new design method; (iii) field testing. This paper describes the framework on which the new design method is based. Analyses conducted using the new design method are compared with methods used in current practice.

  • CONFERENCE PAPER
    Byrne BW, Mcadam RA, Burd HJ, Houlsby GT, Martin CM, Gavin K, Doherty P, Igoe D, Zdravkovic L, Taborda DMG, Potts DM, Jardine RJ, Sideri M, Schroeder FC, Wood AM, Kallehave D, Gretlund JSet al., 2015,

    Field testing of large diameter piles under lateral loading for offshore wind applications

    , Pages: 1255-1260

    © The authors and ICE Publishing: All rights reserved, 2015. Offshore wind power in the UK, and around Europe, has the potential to deliver significant quantities of renewable energy. The foundation is a critical element in the desi gn. The most common foundation design is a single large diameter pile, termed a monopile. Pile diameters of between 5m and 6m are routinely used, with diameters up to 10m or more, being considered for future designs. Questions have been raised as to whether current design methods for lateral loading are relevant to these very large diameter piles. To explore this problem a joint industry project, PISA, co-ordinated by DONG Energy and the Carbon Trust, has been established. The aim of the project is to develop a new design framework for laterally loaded piles based on new theoretical developments, numerical modelling and bench- marked against a suite of large scale field pile tests. The project began in August 2013 and is scheduled to complete during 2015. This paper briefly outlines the project, focusing on the design of the field testing. The testing involves three sizes of pile, from 0.27m in diameter through to 2.0m in diameter. Two sites will be used; a stiff clay site and a dense sand site. Tests will include monotonic loading and cyclic loading. A suite of site investigation will be carried out to aid interpretation of the field tests, and will involve in-situ testing, standard laboratory testing and more advanced laboratory testing.

  • JOURNAL ARTICLE
    Castelltort S, Whittaker AC, Verges J, 2015,

    Tectonics, sedimentation and surface processes: from the erosional engine to basin deposition

    , Earth Surface Processes and Landforms, Vol: 40, Pages: 1839-1846, ISSN: 1096-9837
  • JOURNAL ARTICLE
    Civiero C, Hammond JOS, Goes S, Fishwick S, Ahmed A, Ayele A, Doubre C, Goitom B, Keir D, Kendall J-M, Leroy S, Ogubazghi G, Ruempker G, Stuart GWet al., 2015,

    Multiple mantle upwellings in the transition zone beneath the northern East-African Rift system from relative P-wave travel-time tomography

    , GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, Vol: 16, Pages: 2949-2968, ISSN: 1525-2027
  • JOURNAL ARTICLE
    Colombero R, Kontoe S, Foti S, Potts DMet al., 2015,

    Numerical modelling of drop load tests

    , SOIL DYNAMICS AND EARTHQUAKE ENGINEERING, Vol: 77, Pages: 279-289, ISSN: 0267-7261
  • CONFERENCE PAPER
    Colombero R, Kontoe S, Foti S, Potts DMet al., 2015,

    Numerical modelling of wave attenuation through soil

    , Pages: 3959-3964

    © The authors and ICE Publishing: All rights reserved, 2015. Numerical analyses of induced ground vibrations play an important role in assessing building safety and comfort. One of the major difficulties is related to the calibration of an adequate source model to be used in the numerical simulation. In this paper the attenuation of waves caused by drop load tests is considered to provide a general framework for the evaluation of vibration attenuation both with empirical laws and numerical simulations. A new equation to reproduce the source signal is suggested and used as input for a dynamic coupled consolidation Finite Element Analysis. The model is validated through comparison with field data obtained at a site in the vicinity of the Tower of Pisa, Italy, from geophones at various distances from the impact source. The calibrated numerical model is then used to study in detail the attenuation of waves from the source and assess the validity of empirical attenuation laws.

  • JOURNAL ARTICLE
    Corbett LB, Bierman PR, Lasher GE, Rood DHet al., 2015,

    Landscape chronology and glacial history in Thule, northwest Greenland

    , QUATERNARY SCIENCE REVIEWS, Vol: 109, Pages: 57-67, ISSN: 0277-3791
  • JOURNAL ARTICLE
    Craske J, Debugne ALR, van Reeuwijk M, 2015,

    Shear-flow dispersion in turbulent jets

    , JOURNAL OF FLUID MECHANICS, Vol: 781, Pages: 28-51, ISSN: 0022-1120
  • JOURNAL ARTICLE
    Craske J, van Reeuwijk M, 2015,

    Energy dispersion in turbulent jets. Part 1. Direct simulation of steady and unsteady jets

    , JOURNAL OF FLUID MECHANICS, Vol: 763, Pages: 500-537, ISSN: 0022-1120
  • JOURNAL ARTICLE
    Craske J, van Reeuwijk M, 2015,

    Energy dispersion in turbulent jets. Part 2. A robust model for unsteady jets

    , JOURNAL OF FLUID MECHANICS, Vol: 763, Pages: 538-566, ISSN: 0022-1120
  • CONFERENCE PAPER
    Cui W, Gawecka KA, Potts DM, Taborda DMG, Zdravković Let al., 2015,

    Numerical modelling of open-loop ground source energy systems

    , Pages: 2523-2528

    © The authors and ICE Publishing: All rights reserved, 2015. The environmental and economic benefits of utilising the ground for extracting and storing heat have been known for a long time. However, only recently have government sustainability policies and rising energy prices encouraged the use of this renewable energy resource. In open-loop systems water is abstracted from one well and re-injected into another after exchanging energy with a building's heating/cooling system using a heat pump. In order to guarantee a good performance of the system, it is fundamental that the possibility of thermal breakthrough occurring is minimised, i.e. that the temperature of the water being abstracted remains unaffected by the injection of warmer/cooler water at the other well. In this paper, the Imperial College Finite Element Program (ICFEP), which is capable of simulating fully coupled thermo-hydro-mechanical behaviour of porous materials, was used to perform two-dimensional analyses of open- loop ground source heat systems. The parametric studies carried out highlight the relative impact on the occurrence of thermal breakthrough of the hydraulic ground conditions and the geometric characteristics of the system, providing an invaluable insight into possible improvements to the current design procedure.

  • JOURNAL ARTICLE
    D'Arcy M, Boluda DCR, Whittaker AC, Carpineti Aet al., 2015,

    Dating alluvial fan surfaces in Owens Valley, California, using weathering fractures in boulders

    , EARTH SURFACE PROCESSES AND LANDFORMS, Vol: 40, Pages: 487-501, ISSN: 0197-9337
  • BOOK CHAPTER
    Davies DR, Goes S, Lau HCP, 2015,

    Thermally dominated deep mantle LLSVPs: A review

    , The Earth’s Heterogeneous Mantle: a geophysical, geodynamical, geochemical perspective, Editors: Khan, Deschamps, Publisher: Springer, Pages: 441-477

    The two large low shear-wave velocity provinces (LLSVPs) that dominate lower-mantle structure may hold key information on Earth’s thermal and chemical evolution. It is generally accepted that these provinces are hotter than background mantle and are likely the main source of mantle plumes. Increasingly, it is also proposed that they hold a dense (primitive and/or recycled) compositional com- ponent. The principle evidence that LLSVPs may represent thermo-chemical ‘piles’ comes from seismic constraints, including: (i) their long-wavelength nature; (ii) sharp gradients in shear-wave velocity at their margins; (iii) non-Gaussian distributions of deep mantle shear-wave velocity anomalies; (iv) anti-correlated shear-wave and bulk-sound velocity anomalies (and elevated ratios between shear- and compressional-wave velocity anomalies); (v) anti-correlated shear-wave and density anomalies; and (vi) 1-D/radial profiles of seismic velocity that deviate from those expected for an isochemical, well-mixed mantle. In addition, it has been proposed that hotspots and the reconstructed eruption sites of large ig- neous provinces correlate in location with LLSVP margins. In this paper, we review recent results which indicate that the majority of these constraints do not require thermo-chemical piles: they are equally well (or poorly) explained by thermal heterogeneity alone. Our analyses and conclusions are largely based on comparisons between imaged seismic structure and synthetic seismic structures from a set of thermal and thermo-chemical mantle convection models, which are constrained by ∼ 300 Myr of plate motion histories. Modelled physical structure (temperature, pressure and composition) is converted into seismic velocities via a thermodynamic approach that accounts for elastic, anelastic and phase con- tributions and, subsequently, a tomographic resolution filter is applied to account for the damping and geographic bias inherent to seismic imaging. Our re

  • JOURNAL ARTICLE
    Davies DR, Goes S, Sambridge M, 2015,

    On the relationship between volcanic hotspot locations, the reconstructed eruption sites of large igneous provinces and deep mantle seismic structure

    , EARTH AND PLANETARY SCIENCE LETTERS, Vol: 411, Pages: 121-130, ISSN: 0012-821X
  • JOURNAL ARTICLE
    Dejong BD, Bierman PR, Newell WL, Rittenour TM, Mahan SA, Balco G, Rood DHet al., 2015,

    Pleistocene relative sea levels in the Chesapeake Bay region and their implications for the next century

    , GSA Today, Vol: 25, Pages: 4-10, ISSN: 1052-5173

    Today, relative sea-level rise (3.4 mm/yr) is faster in the Chesapeake Bay region than any other location on the Atlantic coast of North America, and twice the global average eustatic rate (1.7 mm/yr). Dated interglacial deposits suggest that relative sea levels in the Chesapeake Bay region deviate from global trends over a range of timescales. Glacio-isostatic adjustment of the land surface from loading and unloading of continental ice is likely responsible for these deviations, but our understanding of the scale and timeframe over which isostatic response operates in this region remains incomplete because dated sea-level proxies are mostly limited to the Holocene and to deposits 80 ka or older. To better understand glacio-isostatic control over past and present relative sea level, we applied a suite of dating methods to the stratigraphy of the Blackwater National Wildlife Refuge, one of the most rapidly subsiding and lowest-elevation surfaces bordering Chesapeake Bay. Data indicate that the region was submerged at least for portions of marine isotope stage (MIS) 3 (ca. 60-30 ka), although multiple proxies suggest that global sea level was 40-80 m lower than present. Today MIS 3 deposits are above sea level because they were raised by the Last Glacial Maximum forebulge, but decay of that same forebulge is causing ongoing subsidence. These results suggest that glacio-isostasy controlled relative sea level in the mid-Atlantic region for tens of thousands of years following retreat of the Laurentide Ice Sheet and continues to influence relative sea level in the region. Thus, isostatically driven subsidence of the Chesapeake Bay region will continue for millennia, exacerbating the effects of global sea-level rise and impacting the region's large population centers and valuable coastal natural resources.

  • JOURNAL ARTICLE
    Dilib FA, Jackson MD, Zadeh AM, Aasheim R, Arland K, Gyllensten AJ, Erlandsen SMet al., 2015,

    Closed-Loop Feedback Control in Intelligent Wells: Application to a Heterogeneous, Thin Oil-Rim Reservoir in the North Sea

    , SPE RESERVOIR EVALUATION & ENGINEERING, Vol: 18, Pages: 69-83, ISSN: 1094-6470
  • JOURNAL ARTICLE
    Doherty P, Igoe D, Murphy G, Gavin K, Preston J, McAvoy C, Byrne BW, Mcadam R, Burd HJ, Houlsby GT, Martin CM, Zdravkovic L, Taborda DMG, Potts DM, Jardine RJ, Sideri M, Schroeder FC, Wood AM, Kallehave D, Gretlund JSet al., 2015,

    Field validation of fibre Bragg grating sensors for measuring strain on driven steel piles

    , GEOTECHNIQUE LETTERS, Vol: 5, Pages: 74-79, ISSN: 2049-825X
  • JOURNAL ARTICLE
    Dooley TP, Jackson MPA, Jackson CA-L, Hudec MR, Rodriguez CRet al., 2015,

    Enigmatic structures within salt walls of the Santos Basin—Part 2: Mechanical explanation from physical modeling

    , Journal of Structural Geology, Vol: 75, Pages: 163-187, ISSN: 0191-8141

    Jackson et al. (this volume) used 3D seismic reflection data to describe intrasalt deformation in salt walls in the Santos Basin. They focused on the origin of enigmatic allochthonous salt sheets of older evaporites (A1 unit) emplaced above overlying stratified evaporites (A2–A4 units). Their kinematic model incorporates: (i) initial inward flow and thickening of A1 salt within the rising wall, and arching of A2–A4 overburden; (ii) breaching of the arched overburden, ascent of mobile A1 evaporites along single or multiple feeders, and emplacement of upper-wall sheets or canopies; and (iii) a component of regional shortening within the salt. This companion paper uses physical modeling to explain how and why these structures occur and proposes a mechanical basis for the kinematic model. Our first two models simulated salt having uniform internal density, with walls growing by (i) initially symmetric differential loading and (ii) initially symmetric differential loading plus shortening. These models reproduced anticlines and injection folds seen in the simpler deformed walls in the Santos Basin. However, neither model reproduced the most complex structures within the Santos evaporites, which are: (i) allochthonous intrusions, (ii) steep feeders, and (iii) recumbent synclines. Thus, differential loading and shortening alone are insufficient to generate these complex structures. In our third model, a less-dense lower evaporite (A1) was overlain by denser upper evaporites (A2–A4), similar to the density structure found by Santos Basin wellbores. The wall rose solely by differential loading. In this model, A1 breached the overlying evaporites to form vertical diapirs feeding salt sheets and salt wings in the upper part of the salt wall. Breakthrough of A1 folded A2–A4 evaporites into recumbent synclines. Model sections closely resemble Santos seismic examples, suggesting that the key to forming these complex intrasalt structures is a density inversi

  • CONFERENCE PAPER
    Dubasaru V, Zdravkovic L, Taborda DMG, Hardy Set al., 2015,

    Influence of pile raft stiffness on building behaviour in a tunnel-pile clash scenario

    , Pages: 455-460

    © The authors and ICE Publishing: All rights reserved, 2015. In a modern urban environment, the underground space becomes increasingly congested due to the high value of the land that forces the new infrastructure projects to be constructed deeper into the ground. For each new project, the potential of both expected and unexpected clashes between new tunnel alignments and the foundations of the existing structures becomes more probable. However, to date, the research on tunnel-pile clashes has been scarce. In the current study, the effects of such a situation are studied by carrying out finite element analyses for a scenario that is typical in the London ground profile. A parametric study was conducted to investigate the influence of the pile raft bending stiffness on the building settlement and the change in piles' axial forces. It is shown that an increased raft bending stiffiiess helps to transfer the load from the trimmed pile to the adjacent piles, thus reducing the settlement of the trimmed pile. In the process of tunnel excavation, the pile settles due to the soil-induced downdrag and the loss of both its base and part of its shaft capacity. It is concluded that the tunnel-pile clash has a large impact on the surface structure, piles and tunnel itself.

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