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Micromechanics of soil responses in cyclic simple shear tests

Cui, Liang, Bhattacharya, Subhamoy and Nikitas, Georgios (2017) Micromechanics of soil responses in cyclic simple shear tests In: Powders & Grains 2017, 3 - 7 July 2017, Montpellier.

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Abstract

Offshore wind turbine (OWT) foundations are subjected to a combination of cyclic and dynamic loading arising from wind, wave, rotor and blade shadowing. Under cyclic loading, most soils change their characteristics including stiffness, which may cause the system natural frequency to approach the loading frequency and lead to unplanned resonance and system damage or even collapse. To investigate such changes and the underlying micromechanics, a series of cyclic simple shear tests were performed on the RedHill 110 sand with different shear strain amplitudes, vertical stresses and initial relative densities of soil. The test results showed that: (a) Vertical accumulated strain is proportional to the shear strain amplitude but inversely proportional to relative density of soil; (b) Shear modulus increases rapidly in the initial loading cycles and then the rate of increase diminishes and the shear modulus remains below an asymptote; (c) Shear modulus increases with increasing vertical stress and relative density, but decreasing with increasing strain amplitude. Coupled DEM simulations were performed using PFC2D to analyse the micromechanics underlying the cyclic behaviour of soils. Micromechanical parameters (e.g. fabric tensor, coordination number) were examined to explore the reasons for the various cyclic responses to different shear strain amplitudes or vertical stresses. Both coordination number and magnitude of fabric anisotropy contribute to the increasing shear modulus.

Item Type: Conference or Workshop Item (Conference Paper)
Divisions : Faculty of Engineering and Physical Sciences > Civil and Environmental Engineering
Authors :
NameEmailORCID
Cui, LiangL.Cui@surrey.ac.ukUNSPECIFIED
Bhattacharya, Subhamoys.bhattacharya@surrey.ac.ukUNSPECIFIED
Nikitas, Georgiosgeorgios.nikitas@surrey.ac.ukUNSPECIFIED
Date : 30 June 2017
Identification Number : 10.1051/epjconf/201714002008
Copyright Disclaimer : © The Authors, published by EDP Sciences. This is an open access article distributed under the terms of the Creative Commons Attribution License 4.0 (http://creativecommons.org/licenses/by/4.0/).
Depositing User : Melanie Hughes
Date Deposited : 18 Jul 2017 09:38
Last Modified : 18 Jul 2017 09:38
URI: http://epubs.surrey.ac.uk/id/eprint/841676

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