The University of Southampton
University of Southampton Institutional Repository

Stiffness of geomaterials at very small strains

Stiffness of geomaterials at very small strains
Stiffness of geomaterials at very small strains
Experiments have been conducted in the triaxial apparatus to observe the behaviour at very small strains of three widely different natural materials: Bothkennar clay, London clay, and a high-porosity Chalk, Local strain measurements made using LVDTs were calibrated by a Fabry-Perot laser interferometer. a displacement accuracy as high as +/-0.027 mum, was obtained, leading to an axial strain accuracy of the order of +/- 10(-4)%. Special care was taken to ensure that the rates of creep reduced to acceptably small Levels before loading commenced. At very small strain levels the observed stress-strain behaviour appeared to be linear for all three materials. The extent of this linear behaviour was similar (0.002-0.003%) for all three materials, despite the maximum stiffness (E-max) ranging over two orders of magnitude. The initial influence of stress change and strain level on secant modulus was relatively small, with stiffnesses at 0.01% strain being of the order of 80-95% of E-max. Effects of loading path were observed, giving different rates of stiffness degradation as a function of strain, but recent stress history effects did not occur even though stress excursions went well beyond the range normally thought to induce plastic strains. Stiffnesses measured in the triaxial apparatus at very small strain levels were found to be similar to those obtained using held geophysical techniques, despite assumptions of isotropy; and the effects of sampling. The implications of these observations for practice are discussed.
chalk, clay, stiffness
0016-8505
245-255
Clayton, C.R.I.
8397d691-b35b-4d3f-a6d8-40678f233869
Heymann, G.
4f086d55-d1c1-48df-a1a3-b552571cb0d3
Clayton, C.R.I.
8397d691-b35b-4d3f-a6d8-40678f233869
Heymann, G.
4f086d55-d1c1-48df-a1a3-b552571cb0d3

Clayton, C.R.I. and Heymann, G. (2001) Stiffness of geomaterials at very small strains. Géotechnique, 51 (3), 245-255. (doi:10.1680/geot.51.3.245.39363).

Record type: Article

Abstract

Experiments have been conducted in the triaxial apparatus to observe the behaviour at very small strains of three widely different natural materials: Bothkennar clay, London clay, and a high-porosity Chalk, Local strain measurements made using LVDTs were calibrated by a Fabry-Perot laser interferometer. a displacement accuracy as high as +/-0.027 mum, was obtained, leading to an axial strain accuracy of the order of +/- 10(-4)%. Special care was taken to ensure that the rates of creep reduced to acceptably small Levels before loading commenced. At very small strain levels the observed stress-strain behaviour appeared to be linear for all three materials. The extent of this linear behaviour was similar (0.002-0.003%) for all three materials, despite the maximum stiffness (E-max) ranging over two orders of magnitude. The initial influence of stress change and strain level on secant modulus was relatively small, with stiffnesses at 0.01% strain being of the order of 80-95% of E-max. Effects of loading path were observed, giving different rates of stiffness degradation as a function of strain, but recent stress history effects did not occur even though stress excursions went well beyond the range normally thought to induce plastic strains. Stiffnesses measured in the triaxial apparatus at very small strain levels were found to be similar to those obtained using held geophysical techniques, despite assumptions of isotropy; and the effects of sampling. The implications of these observations for practice are discussed.

Text
39390-01.pdf - Version of Record
Restricted to Repository staff only
Request a copy

More information

Published date: April 2001
Keywords: chalk, clay, stiffness
Organisations: Civil Engineering & the Environment

Identifiers

Local EPrints ID: 39390
URI: http://eprints.soton.ac.uk/id/eprint/39390
ISSN: 0016-8505
PURE UUID: 49371222-9de8-49e6-a0c7-c8b5167bdb24
ORCID for C.R.I. Clayton: ORCID iD orcid.org/0000-0003-0071-8437

Catalogue record

Date deposited: 28 Jun 2006
Last modified: 16 Mar 2024 03:12

Export record

Altmetrics

Contributors

Author: C.R.I. Clayton ORCID iD
Author: G. Heymann

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×