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Advanced in-situ and laboratory characterisation of the ALPACA chalk research site

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Title: Advanced in-situ and laboratory characterisation of the ALPACA chalk research site
Authors: Vinck, K
Liu, T
Jardine, RJ
Kontoe, S
Ahmadi-Naghadeh, R
Buckley, RM
Byrne, BW
Lawrence, JA
McAdam, RA
Schranz, F
Item Type: Journal Article
Abstract: Low-to-medium density chalk at St Nicholas at Wade, UK, is characterised by intensive testing to inform the interpretation of axial and lateral tests on driven piles. The chalk de-structures when taken to large strains, especially under dynamic loading, leading to remarkably high pore pressures beneath penetrating CPT and driven pile tips, weak putty annuli around their shafts and degraded responses in full-displacement pressuremeter tests. Laboratory tests on carefully formed specimens explore the chalk's unstable structure and markedly time and rate-dependent mechanical behaviour. A clear hierarchy is found between profiles of peak strength with depth of Brazilian tension (BT), drained and undrained triaxial and direct simple shear (DSS) tests conducted from in-situ stress conditions. Highly instrumented triaxial tests reveal the chalk's unusual effective stress paths, markedly brittle failure behaviour from small strains and the effects of consolidating to higher than in-situ stresses. The chalk's mainly sub-vertical jointing and micro-fissuring leads to properties depending on specimen scale, with in-situ mass stiffnesses falling significantly below high-quality laboratory measurements and vertical Young's moduli exceeding horizontal stiffnesses. While compressive strength and stiffness appear relatively insensitive to effective stress levels, consolidation to higher pressures closes micro-fissures, increases stiffness and reduces anisotropy.
Date of Acceptance: 12-Jan-2022
URI: http://hdl.handle.net/10044/1/95527
DOI: 10.1680/jgeot.21.00197
ISSN: 0016-8505
Publisher: ICE Publishing
Journal / Book Title: Géotechnique
Copyright Statement: © 2022 ICE Publishing. This author accepted version is available under a CC-BY licence (https://creativecommons.org/licenses/by/4.0/)
Sponsor/Funder: Engineering & Physical Science Research Council (E
Ørsted WIND POWER A/S
Scottishpower Renewables (UK) Limited
Equinor Energy AS
Siemens Gamesa Renewable Energy A/S
Innogy SE
Eoliennes en Mer Dieppe Le Transport
Parkwind NV
Ørsted WIND POWER A/S
Equinor Energy AS
Parkwind NV
Scottishpower Renewables (UK) Limited
Eoliennes en Mer Dieppe Le Treport
Vattenfall Wind Power Ltd
Innogy SE
Siemens Gamesa Renewable Energy A/S
Engineering and Physical Sciences Research Council
Funder's Grant Number: EP/P033091/1
4700017327
TBC
4590086392
478D/9703582556
PO No: 4300010104
TBC
N/A (Linked to: EP/P033091/1)
4700027618
N/A
CISM_P85292
PO 4700338074
CISM_P84273
CISM_P84279
CISM_P85295
PO : 9705600999
CISM_P89393
Keywords: Geological & Geomatics Engineering
0905 Civil Engineering
0907 Environmental Engineering
0914 Resources Engineering and Extractive Metallurgy
Publication Status: Published online
Online Publication Date: 2022-03-14
Appears in Collections:Civil and Environmental Engineering



This item is licensed under a Creative Commons License Creative Commons