911½ñÈÕºÚÁÏ

Search or filter publications

Search publications Search

Filter by type:

Filter by publication type

• Book
• Book chapter
• Conference paper
• Journal article
• Patent
• Report
• Software

Filter by year:

Filter from 202620252024202320222021 to Filter to 202620252024202320222021

---

Search results

• Conference paper
  Eleftheriou E, Taborda D, 2024,
  , XVIII European Conference on Soil Mechanics and Geotechnical Engineering
  • Cite
• Journal article
  Wen K, Kontoe S, Jardine R, Liu Tet al., 2024,
  , Computers and Geotechnics, Vol: 172, ISSN: 0266-352X

  Percussive driving in low-to-medium density chalk creates a thin annulus of fully de-structured ‘putty’ chalk around pile shafts and an outer annular zone where fracturing is more intense than in the natural chalk. This damage and the related generation, and subsequent equalisation, of excess pore pressures impacts the piles’ time-dependent axial loading behaviour, as do other ageing processes. This paper presents finite element analyses of open steel tubular piles driven for the recent ALPACA and ALPACA Plus research projects under monotonic axial loading to failure after extended ageing periods. A nonlinear elastic stiffness model with a nonlocal deviatoric strain-based Mohr-Coulomb failure criterion was employed, with different sets of properties to represent the de-structured, fractured chalk and intact chalk. It is shown that the piles’ axial responses are mainly controlled by the puttified chalk annuli. A simplified but efficient means is adopted to impose pre-loading chalk effective stress conditions that explicitly capture the effects of installation damage and subsequent ageing. The potential for strain-softening in the brittle chalk is examined and the effective stress paths developed in representative chalk elements throughout the loading are considered in conjunction with the mobilisation of accumulated deviatoric strains. The simulations indicate 264% higher shaft capacity in compression than in tension, which is mainly attributed to the internal chalk plug.

  • Abstract
  • Cite
• Conference paper
  Yang Y, Tantivangphaisal P, Ruiz Lopez A, Taborda Det al., 2024,

  A surrogate model for the design of offshore monopile foundations

  , MadeAI 2024 – Modelling, Data Analytics and AI in Engineering
  • Cite
• Conference paper
  MA S, Kontoe S, Taborda D, 2024,
  , 8th International Conference on Earthquake Geotechnical Engineering, Publisher: The Japanese Geotechnical Society, Pages: 848-853

  Simplified liquefaction assessment procedures have been widely used to estimate the severity of liquefaction under earthquake loading, which is often confirmed by the presence of sand boils. Back analyses of case studies have shown that the simplified assessment procedures can overestimate or underestimate the liquefaction potential of a deposit (i.e. false positives and false negatives respectively). The occurrence and severity of sand boils are highly dependent on the soil permeability and the hydro-mechanical interaction of cross-layers (system response effects), which the simplified liquefaction assessment procedures do not account for. Additionally, the variation of hydraulic conditions during and after the earthquake shaking significantly affects the evolution of sand boils. In this study, the layered system effects on liquefiable deposits are examined through dynamic nonlinear effective stress analysis. Scenarios where a liquefiable layer is interbedded within materials of distinct hydro-mechanical characteristics are examined parametrically employing the fully coupled (u-p) finite element software PLAXIS. The influence of the presence and the characteristics of non-liquefied or low-permeability layers surrounding the liquefiable layer on the development of sand boils is investigated.

  • Abstract
  • Cite
• Journal article
  Pedro AMG, Taborda DMG, 2024,
  , Data in Brief, Vol: 54, ISSN: 2352-3409

  Experimental and computational data are presented for Areolas da Estefania, a geomaterial which is crucial for the development of the underground infrastructure of the city of Lisbon, Portugal. The experimental data comprise the particle size distribution of the material and measurements obtained during a series of strain-controlled triaxial compression tests performed on intact samples. The behaviour of this material at a wide range of strains, under constant mean effective stress levels of 130 kPa, 300 kPa and 400 kPa is established, with the presented dataset containing information on stress (mean effective stress and deviatoric stress) and strain states (axial strain and volumetric strain). These are complemented by the results of bender element tests imposing vertically-travelling waves for characterisation at very small strains. Complementarily, the computational dataset establishes a reference reproduction of the response of Areolas da Estefania using a material model which combines a non-linear small stiffness formulation with a state-dependent strength and plastic dilatancy. Overall, this dataset can be used as a reference when assessing the behaviour of other samples of Areolas da Estefania or comparable materials, or when evaluating constitutive models for granular geomaterials.

  • Abstract
  • Cite
• Journal article
  Liu R, Taborda DMG, 2024,
  , Renewable Energy, Vol: 225, ISSN: 0960-1481

  Thermo-active piles are extensively utilised for providing low carbon heating and cooling to buildings and are a key technology to help fulfilling sustainability targets. However, when deployed as a group, thermal interference between neighbouring piles can significantly impact the overall thermal performance of the system. This study first explores the lower and upper bounds of thermal interference by comparing the thermal performance of a single pile with that of infinitely-large thermo-active pile groups. A simplified method is subsequently proposed to quantify the effects of thermal interference and estimate the thermal performance of thermo-active piles arranged in realistic group geometries. This method involves deriving thermal interaction factor curves that represent the penalty on the thermal performance of a pile due to the presence of another pile in its vicinity. By applying the principle of superposition, the penalty on the thermal performance of any pile within any group can be calculated using these thermal interaction factor curves. The accuracy of the simplified method is validated through comparisons with numerical analysis, demonstrating its ability to estimate accurately the thermal performance of 2 × 2 and a 3 × 3 thermo-active pile groups, regardless of the pile diameter considered.

  • Abstract
  • Cite
• Conference paper
  Moller J, Kontoe S, Taborda D, Tantivangphaisal Pet al., 2024,
  , 8th International Conference on Earthquake Geotechnical Engineering

  Advanced constitutive models can be used to simulate the effects of soil liquefaction on foundations and buildings in dynamic Finite Element analyses. While various constitutive models have been applied in numerical studies considering one-time cyclic loading, there remains a need to investigate their performance for repeated cyclic loading events. Deposits in seismic areas are likely to be subjected to multiple consecutive earthquakes and aftershocks. However, the impact of the previous shaking history on the cyclic resistance of the soil and its post-liquefaction static response is the subject of ongoing research and is not yet fully understood. Based on findings from experimental studies, this paper presents an assessment of a constitutive model and its ability to capture the effects of the loading history on the sand response. This involves the simulation of laboratory element tests for different cyclic loading, reconsolidation and monotonic shearing series. A particular focus lies on model features incorporated to simulate cyclic mobility at low effective stress levels, as well as the anisotropic post-liquefaction response of the material.

  • Abstract
  • Cite
• Conference paper
  Kontoe S, Moller J, Taborda D, 2024,
  , 8th International Conference on Earthquake Geotechnical Engineering

  Following the rapid expansion of offshore wind farms in seismic areas, this study examines the hurdles encountered when applying conventional seismic evaluation methods, originally devised for onshore structures, to offshore installations. This includes the assessment of liquefaction offshore at large depths and its consequences on the response of offshore wind turbines supported by monopile foundations. With the aid of 3D dynamic finite element analysis of the entire SSI system (tower, monopile foundation and soil domain), it is shown that the resonant frequencies of the examined 5MW turbine were excited for the considered ground motion, inducing significant nonlinearity in the soil surrounding the monopile foundation. The vertical seismic motion, often overlooked in seismic design, is also discussed as it bears significance for the response of offshore wind turbines. Simple site response analysis for vertical ground motion emphasizes the need to consider the entire water column and soil profile depth to the bedrock for an accurate representation of the soil-water system's compression natural frequency in offshore environments.

  • Abstract
  • Cite
• Journal article
  Tsiampousi A, Day MC, Petalas A, 2024,
  , Geomechanics for Energy and the Environment, Vol: 38, ISSN: 2352-3808

  Engineered soil barriers have been proposed to prevent rainwater infiltration into the underlying soil, thus improving stability of sloping ground. The use of engineered barriers on flat ground as means of preventing flooding has also been explored. This paper aims to provide proof-of-concept as to the potential efficiency of engineered barriers in minimising soil shrinkage and swelling arising from seasonal variations of water content and pore water pressures within the ground due to its interaction with the atmosphere. A series of 2-dimensional, hydro-mechanically coupled finite element analyses were conducted to this effect. Emphasis was placed on accurately modelling the stiffness of the underlying soil, accounting for its small-strain behaviour, as well as the hydraulic behaviour of all the layers involved. The results confirm that it is possible to engineer barriers to minimise shrinkage/swelling in greenfield, as well as urban, conditions and highlight the influence of barrier geometry and configuration, so that recommendations for the design of such barriers can be made.

  • Abstract
  • Cite
• Conference paper
  Liu RYW, Taborda D, 2023,
  , Symposium on Energy Geotechnics 2023, Publisher: TU Delft OPEN Publishing, Pages: 1-2

  Thermo-active piles differ from conventional piles in a way that they have pipes embedded within them, which allow a carrier fluid to circulate through and exchange heat with the ground, in order to provide low carbon heating and cooling. Sustainability targets, such as the Merton Rule, which requires a proportion of the energy demand of the building to be generated on site using renewable sources [1, 2], have facilitated the growing popularity of designing piles to be thermo-active in the United Kingdom [3, 4, 5]. In order to fulfil these sustainability targets and to determine accurately the energy savings by designing piles to be thermo-active, the thermal performance of thermo-active piles has to be determined.

  • Abstract
  • Cite
• Journal article
  Liu RYW, Taborda DMG, 2023,
  , ENVIRONMENTAL GEOTECHNICS, ISSN: 2051-803X
  • Cite
• Conference paper
  Georgiadis K, Taborda D, Tsiampousi K, 2023,

  Effect of small strain stiffness on the lateral behaviour of monopile foundations for offshore wind turbines

  , 9th Hellenic Conference on Geotechnical Engineering
  • Cite
• Conference paper
  Moller JK, Kontoe S, Taborda D, 2023,
  , Symposium on Energy Geotechnics 2023
  • Cite
• Conference paper
  Kontoe S, Jardine R, Möller J-K, Taborda Det al., 2023,

  Dynamic response of offshore foundations – from pile installation to seismic performance

  , SECED 2023: Earthquake Engineering & Dynamics for a Sustainable Future, Publisher: Society for Earthquake and Civil Engineering Dynamics, Pages: 1-12

  Dynamic analysis has an important role to play in the rapid expansion of offshore windinstallations worldwide, as it affects multiple design stages. This paper highlights the use ofdynamic analysis in two distinct aspects of offshore geotechnics. It first gives examples fromrecent Joint Industry Projects where consistent procedures for wave propagation analysis basedon impact pile driving and restrike data were established, ultimately resulting in the developmentof more reliable tools for the assessment of axial capacity of piles supporting jacket structures.Following the rapid expansion of offshore wind farms in seismic areas, the second part of thepaper discusses some of the challenges in transferring some of the existing seismic assessmentprocedures, which were established for conventional onshore structures, to offshore structures.This includes the assessment of liquefaction offshore at large depths and its consequences onthe response of offshore wind turbines supported by monopile foundations.

  • Abstract
  • Cite
• Conference paper
  Kumar R, Taborda DMG, Kontoe S, Cheng Set al., 2023,
  , Innovative Geotechnologies for Energy Transition, Publisher: Society of Underwater Technology
  • Cite

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.